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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Zoller%2C+P&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Zoller%2C+P&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Zoller%2C+P&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Zoller%2C+P&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> <li> <a href="/search/?searchtype=author&query=Zoller%2C+P&start=150" class="pagination-link " aria-label="Page 4" aria-current="page">4 </a> </li> <li> <a href="/search/?searchtype=author&query=Zoller%2C+P&start=200" class="pagination-link " aria-label="Page 5" aria-current="page">5 </a> </li> <li> <a href="/search/?searchtype=author&query=Zoller%2C+P&start=250" class="pagination-link " aria-label="Page 6" aria-current="page">6 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.05067">arXiv:2502.05067</a> <span> [<a href="https://arxiv.org/pdf/2502.05067">pdf</a>, <a href="https://arxiv.org/format/2502.05067">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Programming optical-lattice Fermi-Hubbard quantum simulators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tabares%2C+C">Cristian Tabares</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Gonz%C3%A1lez-Cuadra%2C+D">Daniel Gonz谩lez-Cuadra</a>, <a href="/search/quant-ph?searchtype=author&query=Gonz%C3%A1lez-Tudela%2C+A">Alejandro Gonz谩lez-Tudela</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2502.05067v1-abstract-short" style="display: inline;"> Fermionic atoms in optical lattices provide a native implementation of Fermi-Hubbard (FH) models that can be used as analog quantum simulators of many-body fermionic systems. Recent experimental advances include the time-dependent local control of chemical potentials and tunnelings, and thus enable to operate this platform digitally as a programmable quantum simulator. Here, we explore these oppor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.05067v1-abstract-full').style.display = 'inline'; document.getElementById('2502.05067v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.05067v1-abstract-full" style="display: none;"> Fermionic atoms in optical lattices provide a native implementation of Fermi-Hubbard (FH) models that can be used as analog quantum simulators of many-body fermionic systems. Recent experimental advances include the time-dependent local control of chemical potentials and tunnelings, and thus enable to operate this platform digitally as a programmable quantum simulator. Here, we explore these opportunities and develop ground-state preparation algorithms for different fermionic models, based on the ability to implement both single-particle and many-body, high-fidelity fermionic gates, as provided by the native FH Hamiltonian. In particular, we first design variational, pre-compiled quantum circuits to prepare the ground state of the natively implemented FH model, with significant speedups relative to competing adiabatic protocols. Besides, the versatility of this variational approach enables to target extended FH models, i.e., including terms that are not natively realized on the platform. As an illustration, we include next-nearest-neighbor tunnelings at finite dopings, relevant in the context of $d$-wave superconductivity. Furthermore, we discuss how to approximate the imaginary-time evolution using variational fermionic circuits, both as an alternative state-preparation strategy, and as a subroutine for the Quantum Lanczos algorithm to further improve the energy estimation. We benchmark our protocols for ladder geometries, though they can be readily applied to 2D experimental setups to address regimes beyond the capabilities of current classical methods. These results pave the way for more efficient and comprehensive explorations of relevant many-body phases with existing programmable fermionic quantum simulators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.05067v1-abstract-full').style.display = 'none'; document.getElementById('2502.05067v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.16081">arXiv:2412.16081</a> <span> [<a href="https://arxiv.org/pdf/2412.16081">pdf</a>, <a href="https://arxiv.org/format/2412.16081">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Error-corrected fermionic quantum processors with neutral atoms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ott%2C+R">Robert Ott</a>, <a href="/search/quant-ph?searchtype=author&query=Gonz%C3%A1lez-Cuadra%2C+D">Daniel Gonz谩lez-Cuadra</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Kaufman%2C+A+M">Adam M. Kaufman</a>, <a href="/search/quant-ph?searchtype=author&query=Pichler%2C+H">Hannes Pichler</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2412.16081v1-abstract-short" style="display: inline;"> Many-body fermionic systems can be simulated in a hardware-efficient manner using a fermionic quantum processor. Neutral atoms trapped in optical potentials can realize such processors, where non-local fermionic statistics are guaranteed at the hardware level. Implementing quantum error correction in this setup is however challenging, due to the atom-number superselection present in atomic systems… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.16081v1-abstract-full').style.display = 'inline'; document.getElementById('2412.16081v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.16081v1-abstract-full" style="display: none;"> Many-body fermionic systems can be simulated in a hardware-efficient manner using a fermionic quantum processor. Neutral atoms trapped in optical potentials can realize such processors, where non-local fermionic statistics are guaranteed at the hardware level. Implementing quantum error correction in this setup is however challenging, due to the atom-number superselection present in atomic systems, that is, the impossibility of creating coherent superpositions of different particle numbers. In this work, we overcome this constraint and present a blueprint for an error-corrected fermionic quantum computer that can be implemented using current experimental capabilities. To achieve this, we first consider an ancillary set of fermionic modes and design a fermionic reference, which we then use to construct superpositions of different numbers of referenced fermions. This allows us to build logical fermionic modes that can be error corrected using standard atomic operations. Here, we focus on phase errors, which we expect to be a dominant source of errors in neutral-atom quantum processors. We then construct logical fermionic gates, and show their implementation for the logical particle-number conserving processes relevant for quantum simulation. Finally, our protocol is illustrated using a minimal fermionic circuit, where it leads to a quadratic suppression of the logical error rate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.16081v1-abstract-full').style.display = 'none'; document.getElementById('2412.16081v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.16558">arXiv:2410.16558</a> <span> [<a href="https://arxiv.org/pdf/2410.16558">pdf</a>, <a href="https://arxiv.org/format/2410.16558">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> </div> <p class="title is-5 mathjax"> Observation of string breaking on a (2 + 1)D Rydberg quantum simulator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gonzalez-Cuadra%2C+D">Daniel Gonzalez-Cuadra</a>, <a href="/search/quant-ph?searchtype=author&query=Hamdan%2C+M">Majd Hamdan</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Braverman%2C+B">Boris Braverman</a>, <a href="/search/quant-ph?searchtype=author&query=Kornjaca%2C+M">Milan Kornjaca</a>, <a href="/search/quant-ph?searchtype=author&query=Lukin%2C+A">Alexander Lukin</a>, <a href="/search/quant-ph?searchtype=author&query=Cantu%2C+S+H">Sergio H. Cantu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fangli Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Sheng-Tao Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Keesling%2C+A">Alexander Keesling</a>, <a href="/search/quant-ph?searchtype=author&query=Lukin%2C+M+D">Mikhail D. Lukin</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Bylinskii%2C+A">Alexei Bylinskii</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.16558v1-abstract-short" style="display: inline;"> Lattice gauge theories (LGTs) describe a broad range of phenomena in condensed matter and particle physics. A prominent example is confinement, responsible for bounding quarks inside hadrons such as protons or neutrons. When quark-antiquark pairs are separated, the energy stored in the string of gluon fields connecting them grows linearly with their distance, until there is enough energy to create… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16558v1-abstract-full').style.display = 'inline'; document.getElementById('2410.16558v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.16558v1-abstract-full" style="display: none;"> Lattice gauge theories (LGTs) describe a broad range of phenomena in condensed matter and particle physics. A prominent example is confinement, responsible for bounding quarks inside hadrons such as protons or neutrons. When quark-antiquark pairs are separated, the energy stored in the string of gluon fields connecting them grows linearly with their distance, until there is enough energy to create new pairs from the vacuum and break the string. While such phenomena are ubiquitous in LGTs, simulating the resulting dynamics is a challenging task. Here, we report the observation of string breaking in synthetic quantum matter using a programmable quantum simulator based on neutral atom arrays. We show that a (2+1)D LGT with dynamical matter can be efficiently implemented when the atoms are placed on a Kagome geometry, with a local U(1) symmetry emerging from the Rydberg blockade, while long-range Rydberg interactions naturally give rise to a linear confining potential for a pair of charges, allowing us to tune both their masses as well as the string tension. We experimentally map out the corresponding phase diagram by adiabatically preparing the ground state of the atom array in the presence of defects, and observe substructure of the confined phase, distinguishing regions dominated by fluctuating strings or by broken string configurations. Finally, by harnessing local control over the atomic detuning, we quench string states and observe string breaking dynamics exhibiting a many-body resonance phenomenon. Our work paves a way to explore phenomena in high-energy physics using programmable quantum simulators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16558v1-abstract-full').style.display = 'none'; document.getElementById('2410.16558v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.12645">arXiv:2408.12645</a> <span> [<a href="https://arxiv.org/pdf/2408.12645">pdf</a>, <a href="https://arxiv.org/format/2408.12645">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> </div> </div> <p class="title is-5 mathjax"> Probing topological entanglement on large scales </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ott%2C+R">Robert Ott</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Maskara%2C+N">Nishad Maskara</a>, <a href="/search/quant-ph?searchtype=author&query=Lukin%2C+M+D">Mikhail D. Lukin</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Pichler%2C+H">Hannes Pichler</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.12645v1-abstract-short" style="display: inline;"> Topologically ordered quantum matter exhibits intriguing long-range patterns of entanglement, which reveal themselves in subsystem entropies. However, measuring such entropies, which can be used to certify topological order, on large partitions is challenging and becomes practically unfeasible for large systems. We propose a protocol based on local adiabatic deformations of the Hamiltonian which e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.12645v1-abstract-full').style.display = 'inline'; document.getElementById('2408.12645v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.12645v1-abstract-full" style="display: none;"> Topologically ordered quantum matter exhibits intriguing long-range patterns of entanglement, which reveal themselves in subsystem entropies. However, measuring such entropies, which can be used to certify topological order, on large partitions is challenging and becomes practically unfeasible for large systems. We propose a protocol based on local adiabatic deformations of the Hamiltonian which extracts the universal features of long-range topological entanglement from measurements on small subsystems of finite size, trading an exponential number of measurements against a polynomial-time evolution. Our protocol is general and readily applicable to various quantum simulation architectures. We apply our method to various string-net models representing both abelian and non-abelian topologically ordered phases, and illustrate its application to neutral atom tweezer arrays with numerical simulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.12645v1-abstract-full').style.display = 'none'; document.getElementById('2408.12645v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.04421">arXiv:2408.04421</a> <span> [<a href="https://arxiv.org/pdf/2408.04421">pdf</a>, <a href="https://arxiv.org/format/2408.04421">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Dark spin-cats as biased qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kruckenhauser%2C+A">Andreas Kruckenhauser</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+M">Ming Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+H">Han Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Mamaev%2C+M">Mikhail Mamaev</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+P">Pei Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Mao%2C+X">Xuanhui Mao</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Q">Qian Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=van+Bijnen%2C+R">Rick van Bijnen</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.04421v1-abstract-short" style="display: inline;"> We present a biased atomic qubit, universally implementable across all atomic platforms, encoded as a `spin-cat' within ground state Zeeman levels. The key characteristic of our configuration is the coupling of the ground state spin manifold of size $F_g \gg 1$ to an excited Zeeman spin manifold of size $F_e = F_g - 1$ using light. This coupling results in eigenstates of the driven atom that inclu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04421v1-abstract-full').style.display = 'inline'; document.getElementById('2408.04421v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.04421v1-abstract-full" style="display: none;"> We present a biased atomic qubit, universally implementable across all atomic platforms, encoded as a `spin-cat' within ground state Zeeman levels. The key characteristic of our configuration is the coupling of the ground state spin manifold of size $F_g \gg 1$ to an excited Zeeman spin manifold of size $F_e = F_g - 1$ using light. This coupling results in eigenstates of the driven atom that include exactly two dark states in the ground state manifold, which are decoupled from light and immune to spontaneous emission from the excited states. These dark states constitute the `spin-cat', leading to the designation `dark spin-cat'. We demonstrate that under strong Rabi drive and for large $F_g$, the `dark spin-cat' is autonomously stabilized against common noise sources and encodes a qubit with significantly biased noise. Specifically, the bit-flip error rate decreases exponentially with $F_g$ relative to the dephasing rate. We provide an analysis of dark spin-cats, their robustness to noise, and discuss bias-preserving single qubit and entangling gates, exemplified on a Rydberg tweezer platform. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04421v1-abstract-full').style.display = 'none'; document.getElementById('2408.04421v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.03804">arXiv:2406.03804</a> <span> [<a href="https://arxiv.org/pdf/2406.03804">pdf</a>, <a href="https://arxiv.org/format/2406.03804">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="General Relativity and Quantum Cosmology">gr-qc</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Exploring the interplay between mass-energy equivalence, interactions and entanglement in an optical lattice clock </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chu%2C+A">Anjun Chu</a>, <a href="/search/quant-ph?searchtype=author&query=Mart%C3%ADnez-Lahuerta%2C+V+J">Victor J. Mart铆nez-Lahuerta</a>, <a href="/search/quant-ph?searchtype=author&query=Miklos%2C+M">Maya Miklos</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+K">Kyungtae Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Hammerer%2C+K">Klemens Hammerer</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+J">Jun Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Rey%2C+A+M">Ana Maria Rey</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.03804v1-abstract-short" style="display: inline;"> We propose protocols that probe manifestations of the mass-energy equivalence in an optical lattice clock (OLC) interrogated with spin coherent and entangled quantum states. To tune and uniquely distinguish the mass-energy equivalence effects (gravitational redshift and second order Doppler shift) in such setting, we devise a dressing protocol using an additional nuclear spin state. We then analyz… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.03804v1-abstract-full').style.display = 'inline'; document.getElementById('2406.03804v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.03804v1-abstract-full" style="display: none;"> We propose protocols that probe manifestations of the mass-energy equivalence in an optical lattice clock (OLC) interrogated with spin coherent and entangled quantum states. To tune and uniquely distinguish the mass-energy equivalence effects (gravitational redshift and second order Doppler shift) in such setting, we devise a dressing protocol using an additional nuclear spin state. We then analyze the interplay between photon-mediated interactions and gravitational redshift and show that such interplay can lead to entanglement generation and frequency synchronization. In the regime where all atomic spins synchronize, we show the synchronization time depends on the initial entanglement of the state and can be used as a proxy of its metrological gain compared to a classical state. Our work opens new possibilities for exploring the effects of general relativity on quantum coherence and entanglement in OLC experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.03804v1-abstract-full').style.display = 'none'; document.getElementById('2406.03804v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7+17 pages, 4+6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.06768">arXiv:2405.06768</a> <span> [<a href="https://arxiv.org/pdf/2405.06768">pdf</a>, <a href="https://arxiv.org/format/2405.06768">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/2058-9565/ad9ed5">10.1088/2058-9565/ad9ed5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Hamiltonian and Liouvillian learning in weakly-dissipative quantum many-body systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Olsacher%2C+T">Tobias Olsacher</a>, <a href="/search/quant-ph?searchtype=author&query=Kraft%2C+T">Tristan Kraft</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Kraus%2C+B">Barbara Kraus</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.06768v2-abstract-short" style="display: inline;"> We discuss Hamiltonian and Liouvillian learning for analog quantum simulation from non-equilibrium quench dynamics in the limit of weakly dissipative many-body systems. We present and compare various methods and strategies to learn the operator content of the Hamiltonian and the Lindblad operators of the Liouvillian. We compare different ans盲tze based on an experimentally accessible "learning erro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.06768v2-abstract-full').style.display = 'inline'; document.getElementById('2405.06768v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.06768v2-abstract-full" style="display: none;"> We discuss Hamiltonian and Liouvillian learning for analog quantum simulation from non-equilibrium quench dynamics in the limit of weakly dissipative many-body systems. We present and compare various methods and strategies to learn the operator content of the Hamiltonian and the Lindblad operators of the Liouvillian. We compare different ans盲tze based on an experimentally accessible "learning error" which we consider as a function of the number of runs of the experiment. Initially, the learning error decreases with the inverse square root of the number of runs, as the error in the reconstructed parameters is dominated by shot noise. Eventually the learning error remains constant, allowing us to recognize missing ansatz terms. A central aspect of our approaches is to (re-)parametrize ans盲tze by introducing and varying the dependencies between parameters. This allows us to identify the relevant parameters of the system, thereby reducing the complexity of the learning task. Importantly, this (re-)parametrization relies solely on classical post-processing, which is compelling given the finite amount of data available from experiments. We illustrate and compare our methods with two experimentally relevant spin models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.06768v2-abstract-full').style.display = 'none'; document.getElementById('2405.06768v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.04665">arXiv:2405.04665</a> <span> [<a href="https://arxiv.org/pdf/2405.04665">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.132.190001">10.1103/PhysRevLett.132.190001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum sensing with atomic, molecular, and optical platforms for fundamental physics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ye%2C+J">Jun Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.04665v1-abstract-short" style="display: inline;"> Atomic, molecular, and optical (AMO) physics has been at the forefront of the development of quantum science while laying the foundation for modern technology. With the growing capabilities of quantum control of many atoms for engineered many-body states and quantum entanglement, a key question emerges: what critical impact will the second quantum revolution with ubiquitous applications of entangl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.04665v1-abstract-full').style.display = 'inline'; document.getElementById('2405.04665v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.04665v1-abstract-full" style="display: none;"> Atomic, molecular, and optical (AMO) physics has been at the forefront of the development of quantum science while laying the foundation for modern technology. With the growing capabilities of quantum control of many atoms for engineered many-body states and quantum entanglement, a key question emerges: what critical impact will the second quantum revolution with ubiquitous applications of entanglement bring to bear on fundamental physics? In this Essay, we argue that a compelling long-term vision for fundamental physics and novel applications is to harness the rapid development of quantum information science to define and advance the frontiers of measurement physics, with strong potential for fundamental discoveries. As quantum technologies, such as fault-tolerant quantum computing and entangled quantum sensor networks, become much more advanced than today's realization, we wonder what doors of basic science can these tools unlock? We anticipate that some of the most intriguing and challenging problems, such as quantum aspects of gravity, fundamental symmetries, or new physics beyond the minimal standard model, will be tackled at the emerging quantum measurement frontier. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.04665v1-abstract-full').style.display = 'none'; document.getElementById('2405.04665v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 1 figure, Part of a series of Phys. Rev. Lett. Essays which concisely present author visions for the future of their field</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 132, 190001 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.14194">arXiv:2404.14194</a> <span> [<a href="https://arxiv.org/pdf/2404.14194">pdf</a>, <a href="https://arxiv.org/format/2404.14194">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Optimal Multiparameter Metrology: The Quantum Compass Solution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Vasilyev%2C+D+V">Denis V. Vasilyev</a>, <a href="/search/quant-ph?searchtype=author&query=Shankar%2C+A">Athreya Shankar</a>, <a href="/search/quant-ph?searchtype=author&query=Kaubruegger%2C+R">Raphael Kaubruegger</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.14194v1-abstract-short" style="display: inline;"> We study optimal quantum sensing of multiple physical parameters using repeated measurements. In this scenario, the Fisher information framework sets the fundamental limits on sensing performance, yet the optimal states and corresponding measurements that attain these limits remain to be discovered. To address this, we extend the Fisher information approach with a second optimality requirement for… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.14194v1-abstract-full').style.display = 'inline'; document.getElementById('2404.14194v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.14194v1-abstract-full" style="display: none;"> We study optimal quantum sensing of multiple physical parameters using repeated measurements. In this scenario, the Fisher information framework sets the fundamental limits on sensing performance, yet the optimal states and corresponding measurements that attain these limits remain to be discovered. To address this, we extend the Fisher information approach with a second optimality requirement for a sensor to provide unambiguous estimation of unknown parameters. We propose a systematic method integrating Fisher information and Bayesian approaches to quantum metrology to identify the combination of input states and measurements that satisfies both optimality criteria. Specifically, we frame the optimal sensing problem as an optimization of an asymptotic Bayesian cost function that can be efficiently solved numerically and, in many cases, analytically. We refer to the resulting optimal sensor as a `quantum compass' solution, which serves as a direct multiparameter counterpart to the Greenberger-Horne-Zeilinger state-based interferometer, renowned for achieving the Heisenberg limit in single-parameter metrology. We provide exact quantum compass solutions for paradigmatic multiparameter problem of sensing two and three parameters using an SU(2) sensor. Our metrological cost function opens avenues for quantum variational techniques to design low-depth quantum circuits approaching the optimal sensing performance in the many-repetition scenario. We demonstrate this by constructing simple quantum circuits that achieve the Heisenberg limit for vector field and 3D rotations estimation using a limited set of gates available on a trapped-ion platform. Our work introduces and optimizes sensors for a practical notion of optimality, keeping in mind the ultimate goal of quantum sensors to precisely estimate unknown parameters. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.14194v1-abstract-full').style.display = 'none'; document.getElementById('2404.14194v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.08754">arXiv:2401.08754</a> <span> [<a href="https://arxiv.org/pdf/2401.08754">pdf</a>, <a href="https://arxiv.org/format/2401.08754">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.133.163403">10.1103/PhysRevLett.133.163403 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Floquet Flux Attachment in Cold Atomic Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kamal%2C+H">Helia Kamal</a>, <a href="/search/quant-ph?searchtype=author&query=Kemp%2C+J">Jack Kemp</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Y">Yin-Chen He</a>, <a href="/search/quant-ph?searchtype=author&query=Fuji%2C+Y">Yohei Fuji</a>, <a href="/search/quant-ph?searchtype=author&query=Aidelsburger%2C+M">Monika Aidelsburger</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+N+Y">Norman Y. Yao</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.08754v2-abstract-short" style="display: inline;"> Flux attachment provides a powerful conceptual framework for understanding certain forms of topological order, including most notably the fractional quantum Hall effect. Despite its ubiquitous use as a theoretical tool, directly realizing flux attachment in a microscopic setting remains an open challenge. Here, we propose a simple approach to realizing flux attachment in a periodically-driven (Flo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.08754v2-abstract-full').style.display = 'inline'; document.getElementById('2401.08754v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.08754v2-abstract-full" style="display: none;"> Flux attachment provides a powerful conceptual framework for understanding certain forms of topological order, including most notably the fractional quantum Hall effect. Despite its ubiquitous use as a theoretical tool, directly realizing flux attachment in a microscopic setting remains an open challenge. Here, we propose a simple approach to realizing flux attachment in a periodically-driven (Floquet) system of either spins or hard-core bosons. We demonstrate that such a system naturally realizes correlated hopping interactions and provides a sharp connection between such interactions and flux attachment. Starting with a simple, nearest-neighbor, free boson model, we find evidence -- from both a coupled wire analysis and large-scale density matrix renormalization group simulations -- that Floquet flux attachment stabilizes the bosonic integer quantum Hall state at $1/4$ filling (on a square lattice), and the Halperin-221 fractional quantum Hall state at $1/6$ filling (on a honeycomb lattice). At $1/2$ filling on the square lattice, time-reversal symmetry is instead spontaneously broken and bosonic integer quantum Hall states with opposite Hall conductances are degenerate. Finally, we propose an optical-lattice-based implementation of our model on a square lattice and discuss prospects for adiabatic preparation as well as effects of Floquet heating. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.08754v2-abstract-full').style.display = 'none'; document.getElementById('2401.08754v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review Letters, 133(16), 163403 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.04270">arXiv:2401.04270</a> <span> [<a href="https://arxiv.org/pdf/2401.04270">pdf</a>, <a href="https://arxiv.org/format/2401.04270">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> </div> <p class="title is-5 mathjax"> Observing the quantum Mpemba effect in quantum simulations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Joshi%2C+L+K">Lata Kh Joshi</a>, <a href="/search/quant-ph?searchtype=author&query=Franke%2C+J">Johannes Franke</a>, <a href="/search/quant-ph?searchtype=author&query=Rath%2C+A">Aniket Rath</a>, <a href="/search/quant-ph?searchtype=author&query=Ares%2C+F">Filiberto Ares</a>, <a href="/search/quant-ph?searchtype=author&query=Murciano%2C+S">Sara Murciano</a>, <a href="/search/quant-ph?searchtype=author&query=Kranzl%2C+F">Florian Kranzl</a>, <a href="/search/quant-ph?searchtype=author&query=Blatt%2C+R">Rainer Blatt</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Calabrese%2C+P">Pasquale Calabrese</a>, <a href="/search/quant-ph?searchtype=author&query=Roos%2C+C+F">Christian F. Roos</a>, <a href="/search/quant-ph?searchtype=author&query=Joshi%2C+M+K">Manoj K. Joshi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.04270v2-abstract-short" style="display: inline;"> The non-equilibrium physics of many-body quantum systems harbors various unconventional phenomena. In this study, we experimentally investigate one of the most puzzling of these phenomena -- the quantum Mpemba effect, where a tilted ferromagnet restores its symmetry more rapidly when it is farther from the symmetric state compared to when it is closer. We present the first experimental evidence of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04270v2-abstract-full').style.display = 'inline'; document.getElementById('2401.04270v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.04270v2-abstract-full" style="display: none;"> The non-equilibrium physics of many-body quantum systems harbors various unconventional phenomena. In this study, we experimentally investigate one of the most puzzling of these phenomena -- the quantum Mpemba effect, where a tilted ferromagnet restores its symmetry more rapidly when it is farther from the symmetric state compared to when it is closer. We present the first experimental evidence of the occurrence of this effect in a trapped-ion quantum simulator. The symmetry breaking and restoration are monitored through entanglement asymmetry, probed via randomized measurements, and postprocessed using the classical shadows technique. Our findings are further substantiated by measuring the Frobenius distance between the experimental state and the stationary thermal symmetric theoretical state, offering direct evidence of subsystem thermalization. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04270v2-abstract-full').style.display = 'none'; document.getElementById('2401.04270v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 7 figures. Published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 133, 010402, 2024 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.01308">arXiv:2401.01308</a> <span> [<a href="https://arxiv.org/pdf/2401.01308">pdf</a>, <a href="https://arxiv.org/format/2401.01308">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevResearch.6.043284">10.1103/PhysRevResearch.6.043284 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Hamiltonian Learning in Quantum Field Theories </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ott%2C+R">Robert Ott</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Pr%C3%BCfer%2C+M">Maximilian Pr眉fer</a>, <a href="/search/quant-ph?searchtype=author&query=Erne%2C+S">Sebastian Erne</a>, <a href="/search/quant-ph?searchtype=author&query=Tajik%2C+M">Mohammadamin Tajik</a>, <a href="/search/quant-ph?searchtype=author&query=Pichler%2C+H">Hannes Pichler</a>, <a href="/search/quant-ph?searchtype=author&query=Schmiedmayer%2C+J">J枚rg Schmiedmayer</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.01308v1-abstract-short" style="display: inline;"> We discuss Hamiltonian learning in quantum field theories as a protocol for systematically extracting the operator content and coupling constants of effective field theory Hamiltonians from experimental data. Learning the Hamiltonian for varying spatial measurement resolutions gives access to field theories at different energy scales, and allows to learn a flow of Hamiltonians reminiscent of the r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.01308v1-abstract-full').style.display = 'inline'; document.getElementById('2401.01308v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.01308v1-abstract-full" style="display: none;"> We discuss Hamiltonian learning in quantum field theories as a protocol for systematically extracting the operator content and coupling constants of effective field theory Hamiltonians from experimental data. Learning the Hamiltonian for varying spatial measurement resolutions gives access to field theories at different energy scales, and allows to learn a flow of Hamiltonians reminiscent of the renormalization group. Our method, which we demonstrate in both theoretical studies and available data from a quantum gas experiment, promises new ways of addressing the emergence of quantum field theories in quantum simulation experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.01308v1-abstract-full').style.display = 'none'; document.getElementById('2401.01308v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 pages, 8 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Research 6, 043284 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.08108">arXiv:2311.08108</a> <span> [<a href="https://arxiv.org/pdf/2311.08108">pdf</a>, <a href="https://arxiv.org/format/2311.08108">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevX.14.031035">10.1103/PhysRevX.14.031035 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Many-body entropies and entanglement from polynomially-many local measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Ljubotina%2C+M">Marko Ljubotina</a>, <a href="/search/quant-ph?searchtype=author&query=Cirac%2C+J+I">J. Ignacio Cirac</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Serbyn%2C+M">Maksym Serbyn</a>, <a href="/search/quant-ph?searchtype=author&query=Piroli%2C+L">Lorenzo Piroli</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2311.08108v2-abstract-short" style="display: inline;"> Estimating global properties of many-body quantum systems such as entropy or bipartite entanglement is a notoriously difficult task, typically requiring a number of measurements or classical post-processing resources growing exponentially in the system size. In this work, we address the problem of estimating global entropies and mixed-state entanglement via partial-transposed (PT) moments, and sho… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.08108v2-abstract-full').style.display = 'inline'; document.getElementById('2311.08108v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.08108v2-abstract-full" style="display: none;"> Estimating global properties of many-body quantum systems such as entropy or bipartite entanglement is a notoriously difficult task, typically requiring a number of measurements or classical post-processing resources growing exponentially in the system size. In this work, we address the problem of estimating global entropies and mixed-state entanglement via partial-transposed (PT) moments, and show that efficient estimation strategies exist under the assumption that all the spatial correlation lengths are finite. Focusing on one-dimensional systems, we identify a set of approximate factorization conditions (AFCs) on the system density matrix which allow us to reconstruct entropies and PT moments from information on local subsystems. This yields a simple and efficient strategy for entropy and entanglement estimation. Our method could be implemented in different ways, depending on how information on local subsystems is extracted. Focusing on randomized measurements (RMs), providing a practical and common measurement scheme, we prove that our protocol only requires polynomially-many measurements and post-processing operations, assuming that the state to be measured satisfies the AFCs. We prove that the AFCs hold for finite-depth quantum-circuit states and translation-invariant matrix-product density operators, and provide numerical evidence that they are satisfied in more general, physically-interesting cases, including thermal states of local Hamiltonians. We argue that our method could be practically useful to detect bipartite mixed-state entanglement for large numbers of qubits available in today's quantum platforms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.08108v2-abstract-full').style.display = 'none'; document.getElementById('2311.08108v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">30 pages, 10 figures; v2: references added and general revision</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. X 14, 031035 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.12110">arXiv:2310.12110</a> <span> [<a href="https://arxiv.org/pdf/2310.12110">pdf</a>, <a href="https://arxiv.org/format/2310.12110">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Simulating 2D lattice gauge theories on a qudit quantum computer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Meth%2C+M">Michael Meth</a>, <a href="/search/quant-ph?searchtype=author&query=Haase%2C+J+F">Jan F. Haase</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jinglei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Edmunds%2C+C">Claire Edmunds</a>, <a href="/search/quant-ph?searchtype=author&query=Postler%2C+L">Lukas Postler</a>, <a href="/search/quant-ph?searchtype=author&query=Steiner%2C+A">Alex Steiner</a>, <a href="/search/quant-ph?searchtype=author&query=Jena%2C+A+J">Andrew J. Jena</a>, <a href="/search/quant-ph?searchtype=author&query=Dellantonio%2C+L">Luca Dellantonio</a>, <a href="/search/quant-ph?searchtype=author&query=Blatt%2C+R">Rainer Blatt</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Monz%2C+T">Thomas Monz</a>, <a href="/search/quant-ph?searchtype=author&query=Schindler%2C+P">Philipp Schindler</a>, <a href="/search/quant-ph?searchtype=author&query=Muschik%2C+C">Christine Muschik</a>, <a href="/search/quant-ph?searchtype=author&query=Ringbauer%2C+M">Martin Ringbauer</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.12110v3-abstract-short" style="display: inline;"> Particle physics underpins our understanding of the world at a fundamental level by describing the interplay of matter and forces through gauge theories. Yet, despite their unmatched success, the intrinsic quantum mechanical nature of gauge theories makes important problem classes notoriously difficult to address with classical computational techniques. A promising way to overcome these roadblocks… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.12110v3-abstract-full').style.display = 'inline'; document.getElementById('2310.12110v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.12110v3-abstract-full" style="display: none;"> Particle physics underpins our understanding of the world at a fundamental level by describing the interplay of matter and forces through gauge theories. Yet, despite their unmatched success, the intrinsic quantum mechanical nature of gauge theories makes important problem classes notoriously difficult to address with classical computational techniques. A promising way to overcome these roadblocks is offered by quantum computers, which are based on the same laws that make the classical computations so difficult. Here, we present a quantum computation of the properties of the basic building block of two-dimensional lattice quantum electrodynamics, involving both gauge fields and matter. This computation is made possible by the use of a trapped-ion qudit quantum processor, where quantum information is encoded in $d$ different states per ion, rather than in two states as in qubits. Qudits are ideally suited for describing gauge fields, which are naturally high-dimensional, leading to a dramatic reduction in the quantum register size and circuit complexity. Using a variational quantum eigensolver, we find the ground state of the model and observe the interplay between virtual pair creation and quantized magnetic field effects. The qudit approach further allows us to seamlessly observe the effect of different gauge field truncations by controlling the qudit dimension. Our results open the door for hardware-efficient quantum simulations with qudits in near-term quantum devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.12110v3-abstract-full').style.display = 'none'; document.getElementById('2310.12110v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> To be published in Nature Physics (2025) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.00057">arXiv:2306.00057</a> <span> [<a href="https://arxiv.org/pdf/2306.00057">pdf</a>, <a href="https://arxiv.org/format/2306.00057">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-023-06768-0">10.1038/s41586-023-06768-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exploring Large-Scale Entanglement in Quantum Simulation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Joshi%2C+M+K">Manoj K. Joshi</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=van+Bijnen%2C+R">Rick van Bijnen</a>, <a href="/search/quant-ph?searchtype=author&query=Kranzl%2C+F">Florian Kranzl</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Blatt%2C+R">Rainer Blatt</a>, <a href="/search/quant-ph?searchtype=author&query=Roos%2C+C+F">Christian F. Roos</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.00057v1-abstract-short" style="display: inline;"> Entanglement is a distinguishing feature of quantum many-body systems, and uncovering the entanglement structure for large particle numbers in quantum simulation experiments is a fundamental challenge in quantum information science. Here we perform experimental investigations of entanglement based on the entanglement Hamiltonian, as an effective description of the reduced density operator for larg… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.00057v1-abstract-full').style.display = 'inline'; document.getElementById('2306.00057v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.00057v1-abstract-full" style="display: none;"> Entanglement is a distinguishing feature of quantum many-body systems, and uncovering the entanglement structure for large particle numbers in quantum simulation experiments is a fundamental challenge in quantum information science. Here we perform experimental investigations of entanglement based on the entanglement Hamiltonian, as an effective description of the reduced density operator for large subsystems. We prepare ground and excited states of a 1D XXZ Heisenberg chain on a 51-ion programmable quantum simulator and perform sample-efficient `learning' of the entanglement Hamiltonian for subsystems of up to 20 lattice sites. Our experiments provide compelling evidence for a local structure of the entanglement Hamiltonian. This observation marks the first instance of confirming the fundamental predictions of quantum field theory by Bisognano and Wichmann, adapted to lattice models that represent correlated quantum matter. The reduced state takes the form of a Gibbs ensemble, with a spatially-varying temperature profile as a signature of entanglement. Our results also show the transition from area to volume-law scaling of Von Neumann entanglement entropies from ground to excited states. As we venture towards achieving quantum advantage, we anticipate that our findings and methods have wide-ranging applicability to revealing and understanding entanglement in many-body problems with local interactions including higher spatial dimensions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.00057v1-abstract-full').style.display = 'none'; document.getElementById('2306.00057v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 624, 539-544 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.02527">arXiv:2304.02527</a> <span> [<a href="https://arxiv.org/pdf/2304.02527">pdf</a>, <a href="https://arxiv.org/format/2304.02527">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.131.171902">10.1103/PhysRevLett.131.171902 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum and classical spin network algorithms for $q$-deformed Kogut-Susskind gauge theories </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Gonz%C3%A1lez-Cuadra%2C+D">Daniel Gonz谩lez-Cuadra</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.02527v2-abstract-short" style="display: inline;"> Treating the infinite-dimensional Hilbert space of non-abelian gauge theories is an outstanding challenge for classical and quantum simulations. Here, we introduce $q$-deformed Kogut-Susskind lattice gauge theories, obtained by deforming the defining symmetry algebra to a quantum group. In contrast to other formulations, our proposal simultaneously provides a controlled regularization of the infin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.02527v2-abstract-full').style.display = 'inline'; document.getElementById('2304.02527v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.02527v2-abstract-full" style="display: none;"> Treating the infinite-dimensional Hilbert space of non-abelian gauge theories is an outstanding challenge for classical and quantum simulations. Here, we introduce $q$-deformed Kogut-Susskind lattice gauge theories, obtained by deforming the defining symmetry algebra to a quantum group. In contrast to other formulations, our proposal simultaneously provides a controlled regularization of the infinite-dimensional local Hilbert space while preserving essential symmetry-related properties. This enables the development of both quantum as well as quantum-inspired classical Spin Network Algorithms for $q$-deformed gauge theories (SNAQs). To be explicit, we focus on SU(2)$_k$ gauge theories, that are controlled by the deformation parameter $k$ and converge to the standard SU(2) Kogut-Susskind model as $k \rightarrow \infty$. In particular, we demonstrate that this formulation is well suited for efficient tensor network representations by variational ground-state simulations in 2D, providing first evidence that the continuum limit can be reached with $k = \mathcal{O}(10)$. Finally, we develop a scalable quantum algorithm for Trotterized real-time evolution by analytically diagonalizing the SU(2)$_k$ plaquette interactions. Our work gives a new perspective for the application of tensor network methods to high-energy physics and paves the way for quantum simulations of non-abelian gauge theories far from equilibrium where no other methods are currently available. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.02527v2-abstract-full').style.display = 'none'; document.getElementById('2304.02527v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5+4 pages, 4+1 figures; references added, Fig. 3 revised and typos corrected</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 131, 171902 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.08683">arXiv:2303.08683</a> <span> [<a href="https://arxiv.org/pdf/2303.08683">pdf</a>, <a href="https://arxiv.org/format/2303.08683">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.22331/q-2023-10-16-1140">10.22331/q-2023-10-16-1140 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fermion-qudit quantum processors for simulating lattice gauge theories with matter </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Gonz%C3%A1lez-Cuadra%2C+D">Daniel Gonz谩lez-Cuadra</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.08683v2-abstract-short" style="display: inline;"> Simulating the real-time dynamics of lattice gauge theories, underlying the Standard Model of particle physics, is a notoriously difficult problem where quantum simulators can provide a practical advantage over classical approaches. In this work, we present a complete Rydberg-based architecture, co-designed to digitally simulate the dynamics of general gauge theories coupled to matter fields in a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.08683v2-abstract-full').style.display = 'inline'; document.getElementById('2303.08683v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.08683v2-abstract-full" style="display: none;"> Simulating the real-time dynamics of lattice gauge theories, underlying the Standard Model of particle physics, is a notoriously difficult problem where quantum simulators can provide a practical advantage over classical approaches. In this work, we present a complete Rydberg-based architecture, co-designed to digitally simulate the dynamics of general gauge theories coupled to matter fields in a hardware-efficient manner. Ref. [1] showed how a qudit processor, where non-abelian gauge fields are locally encoded and time-evolved, considerably reduces the required simulation resources compared to standard qubit-based quantum computers. Here we integrate the latter with a recently introduced fermionic quantum processor [2], where fermionic statistics are accounted for at the hardware level, allowing us to construct quantum circuits that preserve the locality of the gauge-matter interactions. We exemplify the flexibility of such a fermion-qudit processor by focusing on two paradigmatic high-energy phenomena. First, we present a resource-efficient protocol to simulate the Abelian-Higgs model, where the dynamics of confinement and string breaking can be investigated. Then, we show how to prepare hadrons made up of fermionic matter constituents bound by non-abelian gauge fields, and show how to extract the corresponding hadronic tensor. In both cases, we estimate the required resources, showing how quantum devices can be used to calculate experimentally-relevant quantities in particle physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.08683v2-abstract-full').style.display = 'none'; document.getElementById('2303.08683v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 8 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum 7, 1140 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.06985">arXiv:2303.06985</a> <span> [<a href="https://arxiv.org/pdf/2303.06985">pdf</a>, <a href="https://arxiv.org/format/2303.06985">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1073/pnas.2304294120">10.1073/pnas.2304294120 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fermionic quantum processing with programmable neutral atom arrays </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gonz%C3%A1lez-Cuadra%2C+D">Daniel Gonz谩lez-Cuadra</a>, <a href="/search/quant-ph?searchtype=author&query=Bluvstein%2C+D">Dolev Bluvstein</a>, <a href="/search/quant-ph?searchtype=author&query=Kalinowski%2C+M">Marcin Kalinowski</a>, <a href="/search/quant-ph?searchtype=author&query=Kaubruegger%2C+R">Raphael Kaubruegger</a>, <a href="/search/quant-ph?searchtype=author&query=Maskara%2C+N">Nishad Maskara</a>, <a href="/search/quant-ph?searchtype=author&query=Naldesi%2C+P">Piero Naldesi</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Kaufman%2C+A+M">Adam M. Kaufman</a>, <a href="/search/quant-ph?searchtype=author&query=Lukin%2C+M+D">Mikhail D. Lukin</a>, <a href="/search/quant-ph?searchtype=author&query=Pichler%2C+H">Hannes Pichler</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+J">Jun Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.06985v1-abstract-short" style="display: inline;"> Simulating the properties of many-body fermionic systems is an outstanding computational challenge relevant to material science, quantum chemistry, and particle physics. Although qubit-based quantum computers can potentially tackle this problem more efficiently than classical devices, encoding non-local fermionic statistics introduces an overhead in the required resources, limiting their applicabi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.06985v1-abstract-full').style.display = 'inline'; document.getElementById('2303.06985v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.06985v1-abstract-full" style="display: none;"> Simulating the properties of many-body fermionic systems is an outstanding computational challenge relevant to material science, quantum chemistry, and particle physics. Although qubit-based quantum computers can potentially tackle this problem more efficiently than classical devices, encoding non-local fermionic statistics introduces an overhead in the required resources, limiting their applicability on near-term architectures. In this work, we present a fermionic quantum processor, where fermionic models are locally encoded in a fermionic register and simulated in a hardware-efficient manner using fermionic gates. We consider in particular fermionic atoms in programmable tweezer arrays and develop different protocols to implement non-local tunneling gates, guaranteeing Fermi statistics at the hardware level. We use this gate set, together with Rydberg-mediated interaction gates, to find efficient circuit decompositions for digital and variational quantum simulation algorithms, illustrated here for molecular energy estimation. Finally, we consider a combined fermion-qubit architecture, where both the motional and internal degrees of freedom of the atoms are harnessed to efficiently implement quantum phase estimation, as well as to simulate lattice gauge theory dynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.06985v1-abstract-full').style.display = 'none'; document.getElementById('2303.06985v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Proc. Natl. Acad. Sci. 120, e2304294120 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.07785">arXiv:2302.07785</a> <span> [<a href="https://arxiv.org/pdf/2302.07785">pdf</a>, <a href="https://arxiv.org/format/2302.07785">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.4.020333">10.1103/PRXQuantum.4.020333 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimal and Variational Multi-Parameter Quantum Metrology and Vector Field Sensing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kaubruegger%2C+R">Raphael Kaubruegger</a>, <a href="/search/quant-ph?searchtype=author&query=Shankar%2C+A">Athreya Shankar</a>, <a href="/search/quant-ph?searchtype=author&query=Vasilyev%2C+D+V">Denis V. Vasilyev</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.07785v1-abstract-short" style="display: inline;"> We study multi-parameter sensing of 2D and 3D vector fields within the Bayesian framework for $SU(2)$ quantum interferometry. We establish a method to determine the optimal quantum sensor, which establishes the fundamental limit on the precision of simultaneously estimating multiple parameters with an $N$-atom sensor. Keeping current experimental platforms in mind, we present sensors that have lim… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07785v1-abstract-full').style.display = 'inline'; document.getElementById('2302.07785v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.07785v1-abstract-full" style="display: none;"> We study multi-parameter sensing of 2D and 3D vector fields within the Bayesian framework for $SU(2)$ quantum interferometry. We establish a method to determine the optimal quantum sensor, which establishes the fundamental limit on the precision of simultaneously estimating multiple parameters with an $N$-atom sensor. Keeping current experimental platforms in mind, we present sensors that have limited entanglement capabilities, and yet, significantly outperform sensors that operate without entanglement and approach the optimal quantum sensor in terms of performance. Furthermore, we show how these sensors can be implemented on current programmable quantum sensors with variational quantum circuits by minimizing a metrological cost function. The resulting circuits prepare tailored entangled states and perform measurements in an appropriate entangled basis to realize the best possible quantum sensor given the native entangling resources available on a given sensor platform. Notable examples include a 2D and 3D quantum ``compass'' and a 2D sensor that provides a scalable improvement over unentangled sensors. Our results on optimal and variational multi-parameter quantum metrology are useful for advancing precision measurements in fundamental science and ensuring the stability of quantum computers, which can be achieved through the incorporation of optimal quantum sensors in a quantum feedback loop. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07785v1-abstract-full').style.display = 'none'; document.getElementById('2302.07785v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 8 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.10181">arXiv:2212.10181</a> <span> [<a href="https://arxiv.org/pdf/2212.10181">pdf</a>, <a href="https://arxiv.org/format/2212.10181">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.109.012422">10.1103/PhysRevA.109.012422 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Entanglement phase diagrams from partial transpose moments </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Carrasco%2C+J">Jose Carrasco</a>, <a href="/search/quant-ph?searchtype=author&query=Votto%2C+M">Matteo Votto</a>, <a href="/search/quant-ph?searchtype=author&query=Vitale%2C+V">Vittorio Vitale</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Neven%2C+A">Antoine Neven</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Kraus%2C+B">Barbara Kraus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.10181v1-abstract-short" style="display: inline;"> We present experimentally and numerically accessible quantities that can be used to differentiate among various families of random entangled states. To this end, we analyze the entanglement properties of bipartite reduced states of a tripartite pure state. We introduce a ratio of simple polynomials of low-order moments of the partially transposed reduced density matrix and show that this ratio tak… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.10181v1-abstract-full').style.display = 'inline'; document.getElementById('2212.10181v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.10181v1-abstract-full" style="display: none;"> We present experimentally and numerically accessible quantities that can be used to differentiate among various families of random entangled states. To this end, we analyze the entanglement properties of bipartite reduced states of a tripartite pure state. We introduce a ratio of simple polynomials of low-order moments of the partially transposed reduced density matrix and show that this ratio takes well-defined values in the thermodynamic limit for various families of entangled states. This allows to sharply distinguish entanglement phases, in a way that can be understood from a quantum information perspective based on the spectrum of the partially transposed density matrix. We analyze in particular the entanglement phase diagram of Haar random states, states resulting form the evolution of chaotic Hamiltonians, stabilizer states, which are outputs of Clifford circuits, Matrix Product States, and fermionic Gaussian states. We show that for Haar random states the resulting phase diagram resembles the one obtained via the negativity and that for all the cases mentioned above a very distinctive behaviour is observed. Our results can be used to experimentally test necessary conditions for different types of mixed-state randomness, in quantum states formed in quantum computers and programmable quantum simulators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.10181v1-abstract-full').style.display = 'none'; document.getElementById('2212.10181v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.13406">arXiv:2210.13406</a> <span> [<a href="https://arxiv.org/pdf/2210.13406">pdf</a>, <a href="https://arxiv.org/format/2210.13406">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Autonomous quantum error correction and fault-tolerant quantum computation with squeezed cat qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Q">Qian Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+G">Guo Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yu-Xin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Clerk%2C+A+A">Aashish A. Clerk</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.13406v1-abstract-short" style="display: inline;"> We propose an autonomous quantum error correction scheme using squeezed cat (SC) code against the dominant error source, excitation loss, in continuous-variable systems. Through reservoir engineering, we show that a structured dissipation can stabilize a two-component SC while autonomously correcting the errors. The implementation of such dissipation only requires low-order nonlinear couplings amo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.13406v1-abstract-full').style.display = 'inline'; document.getElementById('2210.13406v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.13406v1-abstract-full" style="display: none;"> We propose an autonomous quantum error correction scheme using squeezed cat (SC) code against the dominant error source, excitation loss, in continuous-variable systems. Through reservoir engineering, we show that a structured dissipation can stabilize a two-component SC while autonomously correcting the errors. The implementation of such dissipation only requires low-order nonlinear couplings among three bosonic modes or between a bosonic mode and a qutrit. While our proposed scheme is device independent, it is readily implementable with current experimental platforms such as superconducting circuits and trapped-ion systems. Compared to the stabilized cat, the stabilized SC has a much lower dominant error rate and a significantly enhanced noise bias. Furthermore, the bias-preserving operations for the SC have much lower error rates. In combination, the stabilized SC leads to substantially better logical performance when concatenating with an outer discrete-variable code. The surface-SC scheme achieves more than one order of magnitude increase in the threshold ratio between the loss rate $魏_1$ and the engineered dissipation rate $魏_2$. Under a practical noise ratio $魏_1/魏_2 = 10^{-3}$, the repetition-SC scheme can reach a $10^{-15}$ logical error rate even with a small mean excitation number of 4, which already suffices for practically useful quantum algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.13406v1-abstract-full').style.display = 'none'; document.getElementById('2210.13406v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.13837">arXiv:2208.13837</a> <span> [<a href="https://arxiv.org/pdf/2208.13837">pdf</a>, <a href="https://arxiv.org/format/2208.13837">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1751-8121/ac8087">10.1088/1751-8121/ac8087 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Digital Quantum Simulation, Learning of the Floquet Hamiltonian, and Quantum Chaos of the Kicked Top </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Olsacher%2C+T">Tobias Olsacher</a>, <a href="/search/quant-ph?searchtype=author&query=Pastori%2C+L">Lorenzo Pastori</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Sieberer%2C+L+M">Lukas M. Sieberer</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2208.13837v1-abstract-short" style="display: inline;"> The kicked top is one of the paradigmatic models in the study of quantum chaos~[F.~Haake et al., \emph{Quantum Signatures of Chaos (Springer Series in Synergetics vol 54)} (2018)]. Recently it has been shown that the onset of quantum chaos in the kicked top can be related to the proliferation of Trotter errors in digital quantum simulation (DQS) of collective spin systems. Specifically, the prolif… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.13837v1-abstract-full').style.display = 'inline'; document.getElementById('2208.13837v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.13837v1-abstract-full" style="display: none;"> The kicked top is one of the paradigmatic models in the study of quantum chaos~[F.~Haake et al., \emph{Quantum Signatures of Chaos (Springer Series in Synergetics vol 54)} (2018)]. Recently it has been shown that the onset of quantum chaos in the kicked top can be related to the proliferation of Trotter errors in digital quantum simulation (DQS) of collective spin systems. Specifically, the proliferation of Trotter errors becomes manifest in expectation values of few-body observables strongly deviating from the target dynamics above a critical Trotter step, where the spectral statistics of the Floquet operator of the kicked top can be predicted by random matrix theory. In this work, we study these phenomena in the framework of Hamiltonian learning (HL). We show how a recently developed Hamiltonian learning protocol can be employed to reconstruct the generator of the stroboscopic dynamics, i.e., the Floquet Hamiltonian, of the kicked top. We further show how the proliferation of Trotter errors is revealed by HL as the transition to a regime in which the dynamics cannot be approximately described by a low-order truncation of the Floquet-Magnus expansion. This opens up new experimental possibilities for the analysis of Trotter errors on the level of the generator of the implemented dynamics, that can be generalized to the DQS of quantum many-body systems in a scalable way. This paper is in memory of our colleague and friend Fritz Haake. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.13837v1-abstract-full').style.display = 'none'; document.getElementById('2208.13837v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Phys. A: Math. Theor. 55 334003 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.01108">arXiv:2206.01108</a> <span> [<a href="https://arxiv.org/pdf/2206.01108">pdf</a>, <a href="https://arxiv.org/format/2206.01108">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> </div> </div> <p class="title is-5 mathjax"> High-dimensional SO(4)-symmetric Rydberg manifolds for quantum simulation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kruckenhauser%2C+A">Andreas Kruckenhauser</a>, <a href="/search/quant-ph?searchtype=author&query=van+Bijnen%2C+R">Rick van Bijnen</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Di+Liberto%2C+M">Marco Di Liberto</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2206.01108v1-abstract-short" style="display: inline;"> We develop a toolbox for manipulating arrays of Rydberg atoms prepared in high-dimensional hydrogen-like manifolds in the regime of linear Stark and Zeeman effect. We exploit the SO(4) symmetry to characterize the action of static electric and magnetic fields as well as microwave and optical fields on the well-structured manifolds of states with principal quantum number $n$. This enables us to con… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.01108v1-abstract-full').style.display = 'inline'; document.getElementById('2206.01108v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.01108v1-abstract-full" style="display: none;"> We develop a toolbox for manipulating arrays of Rydberg atoms prepared in high-dimensional hydrogen-like manifolds in the regime of linear Stark and Zeeman effect. We exploit the SO(4) symmetry to characterize the action of static electric and magnetic fields as well as microwave and optical fields on the well-structured manifolds of states with principal quantum number $n$. This enables us to construct generalized large-spin Heisenberg models for which we develop state-preparation and readout schemes. Due to the available large internal Hilbert space, these models provide a natural framework for the quantum simulation of Quantum Field Theories, which we illustrate for the case of the sine-Gordon and massive Schwinger models. Moreover, these high-dimensional manifolds also offer the opportunity to perform quantum information processing operations for qudit-based quantum computing, which we exemplify with an entangling gate and a state-transfer protocol for the states in the neighborhood of the circular Rydberg level. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.01108v1-abstract-full').style.display = 'none'; document.getElementById('2206.01108v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 + 12 pages, 10 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2205.00981">arXiv:2205.00981</a> <span> [<a href="https://arxiv.org/pdf/2205.00981">pdf</a>, <a href="https://arxiv.org/format/2205.00981">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.131.060601">10.1103/PhysRevLett.131.060601 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fermionic correlation functions from randomized measurements in programmable atomic quantum devices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Naldesi%2C+P">Piero Naldesi</a>, <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Minguzzi%2C+A">Anna Minguzzi</a>, <a href="/search/quant-ph?searchtype=author&query=Cl%C3%A9ment%2C+D">David Cl茅ment</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2205.00981v1-abstract-short" style="display: inline;"> We provide a measurement protocol to estimate 2- and 4-point fermionic correlations in ultra-cold atom experiments. Our approach is based on combining random atomic beam splitter operations, which can be realized with programmable optical landscapes, with high-resolution imaging systems such as quantum gas microscopes. We illustrate our results in the context of the variational quantum eigensolver… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.00981v1-abstract-full').style.display = 'inline'; document.getElementById('2205.00981v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2205.00981v1-abstract-full" style="display: none;"> We provide a measurement protocol to estimate 2- and 4-point fermionic correlations in ultra-cold atom experiments. Our approach is based on combining random atomic beam splitter operations, which can be realized with programmable optical landscapes, with high-resolution imaging systems such as quantum gas microscopes. We illustrate our results in the context of the variational quantum eigensolver algorithm for solving quantum chemistry problems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.00981v1-abstract-full').style.display = 'none'; document.getElementById('2205.00981v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.13644">arXiv:2204.13644</a> <span> [<a href="https://arxiv.org/pdf/2204.13644">pdf</a>, <a href="https://arxiv.org/format/2204.13644">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Propagation of errors and quantitative quantum simulation with quantum advantage </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Flannigan%2C+S">S. Flannigan</a>, <a href="/search/quant-ph?searchtype=author&query=Pearson%2C+N">N. Pearson</a>, <a href="/search/quant-ph?searchtype=author&query=Low%2C+G+H">G. H. Low</a>, <a href="/search/quant-ph?searchtype=author&query=Buyskikh%2C+A">A. Buyskikh</a>, <a href="/search/quant-ph?searchtype=author&query=Bloch%2C+I">I. Bloch</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">P. Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Troyer%2C+M">M. Troyer</a>, <a href="/search/quant-ph?searchtype=author&query=Daley%2C+A+J">A. J. Daley</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.13644v1-abstract-short" style="display: inline;"> The rapid development in hardware for quantum computing and simulation has led to much interest in problems where these devices can exceed the capabilities of existing classical computers and known methods. Approaching this for problems that go beyond testing the performance of a quantum device is an important step, and quantum simulation of many-body quench dynamics is one of the most promising c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.13644v1-abstract-full').style.display = 'inline'; document.getElementById('2204.13644v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.13644v1-abstract-full" style="display: none;"> The rapid development in hardware for quantum computing and simulation has led to much interest in problems where these devices can exceed the capabilities of existing classical computers and known methods. Approaching this for problems that go beyond testing the performance of a quantum device is an important step, and quantum simulation of many-body quench dynamics is one of the most promising candidates for early practical quantum advantage. We analyse the requirements for quantitatively reliable quantum simulation beyond the capabilities of existing classical methods for analogue quantum simulators with neutral atoms in optical lattices and trapped ions. Considering the primary sources of error in analogue devices and how they propagate after a quench in studies of the Hubbard or long-range transverse field Ising model, we identify the level of error expected in quantities we extract from experiments. We conclude for models that are directly implementable that regimes of practical quantum advantage are attained in current experiments with analogue simulators. We also identify the hardware requirements to reach the same level of accuracy with future fault-tolerant digital quantum simulation. Verification techniques are already available to test the assumptions we make here, and demonstrating these in experiments will be an important next step. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.13644v1-abstract-full').style.display = 'none'; document.getElementById('2204.13644v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 19 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.05671">arXiv:2204.05671</a> <span> [<a href="https://arxiv.org/pdf/2204.05671">pdf</a>, <a href="https://arxiv.org/format/2204.05671">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Simulating dynamical phases of chiral $p+ i p$ superconductors with a trapped ion magnet </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Shankar%2C+A">Athreya Shankar</a>, <a href="/search/quant-ph?searchtype=author&query=Yuzbashyan%2C+E+A">Emil A. Yuzbashyan</a>, <a href="/search/quant-ph?searchtype=author&query=Gurarie%2C+V">Victor Gurarie</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Bollinger%2C+J+J">John J. Bollinger</a>, <a href="/search/quant-ph?searchtype=author&query=Rey%2C+A+M">Ana Maria Rey</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.05671v3-abstract-short" style="display: inline;"> Two-dimensional $p+ i p$ superconductors and superfluids are systems that feature chiral behavior emerging from the Cooper pairing of electrons or neutral fermionic atoms with non-zero angular momentum. Their realization has been a longstanding goal because they offer great potential utility for quantum computation and memory. However, they have so far eluded experimental observation both in solid… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.05671v3-abstract-full').style.display = 'inline'; document.getElementById('2204.05671v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.05671v3-abstract-full" style="display: none;"> Two-dimensional $p+ i p$ superconductors and superfluids are systems that feature chiral behavior emerging from the Cooper pairing of electrons or neutral fermionic atoms with non-zero angular momentum. Their realization has been a longstanding goal because they offer great potential utility for quantum computation and memory. However, they have so far eluded experimental observation both in solid state systems as well as in ultracold quantum gases. Here, we propose to leverage the tremendous control offered by rotating two-dimensional trapped-ion crystals in a Penning trap to simulate the dynamical phases of two-dimensional $p+ip$ superfluids. This is accomplished by mapping the presence or absence of a Cooper pair into an effective spin-1/2 system encoded in the ions' electronic levels. We show how to infer the topological properties of the dynamical phases, and discuss the role of beyond mean-field corrections. More broadly, our work opens the door to use trapped ion systems to explore exotic models of topological superconductivity and also paves the way to generate and manipulate skyrmionic spin textures in these platforms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.05671v3-abstract-full').style.display = 'none'; document.getElementById('2204.05671v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main: 9 pages, 4 figures, Appendix: 14 pages, 3 figures, Improved presentation</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.15846">arXiv:2203.15846</a> <span> [<a href="https://arxiv.org/pdf/2203.15846">pdf</a>, <a href="https://arxiv.org/format/2203.15846">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.3.030324">10.1103/PRXQuantum.3.030324 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterization and Verification of Trotterized Digital Quantum Simulation via Hamiltonian and Liouvillian Learning </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pastori%2C+L">Lorenzo Pastori</a>, <a href="/search/quant-ph?searchtype=author&query=Olsacher%2C+T">Tobias Olsacher</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.15846v2-abstract-short" style="display: inline;"> The goal of digital quantum simulation is to approximate the dynamics of a given target Hamiltonian via a sequence of quantum gates, a procedure known as Trotterization. The quality of this approximation can be controlled by the so called Trotter step, that governs the number of required quantum gates per unit simulation time. The stroboscopic dynamics generated by Trotterization is effectively de… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.15846v2-abstract-full').style.display = 'inline'; document.getElementById('2203.15846v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.15846v2-abstract-full" style="display: none;"> The goal of digital quantum simulation is to approximate the dynamics of a given target Hamiltonian via a sequence of quantum gates, a procedure known as Trotterization. The quality of this approximation can be controlled by the so called Trotter step, that governs the number of required quantum gates per unit simulation time. The stroboscopic dynamics generated by Trotterization is effectively described by a time-independent Hamiltonian, referred to as the Floquet Hamiltonian. In this work, we propose Floquet Hamiltonian learning to reconstruct the experimentally realized Floquet Hamiltonian order-by-order in the Trotter step. This procedure is efficient, i.e., it requires a number of measurements that scales polynomially in the system size, and can be readily implemented in state-of-the-art experiments. With numerical examples, we propose several applications of our method in the context of verification of quantum devices: from the characterization of the distinct sources of errors in digital quantum simulators to determining the optimal operating regime of the device. We show that our protocol provides the basis for feedback-loop design and calibration of new types of quantum gates. Furthermore it can be extended to the case of non-unitary dynamics and used to learn Floquet Liouvillians, thereby offering a way of characterizing the dissipative processes present in NISQ quantum devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.15846v2-abstract-full').style.display = 'none'; document.getElementById('2203.15846v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 3, 030324 2022 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.15541">arXiv:2203.15541</a> <span> [<a href="https://arxiv.org/pdf/2203.15541">pdf</a>, <a href="https://arxiv.org/format/2203.15541">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.129.160501">10.1103/PhysRevLett.129.160501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Hardware efficient quantum simulation of non-abelian gauge theories with qudits on Rydberg platforms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gonz%C3%A1lez-Cuadra%2C+D">Daniel Gonz谩lez-Cuadra</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Carrasco%2C+J">Jose Carrasco</a>, <a href="/search/quant-ph?searchtype=author&query=Kraus%2C+B">Barbara Kraus</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.15541v2-abstract-short" style="display: inline;"> Non-abelian gauge theories underlie our understanding of fundamental forces in nature, and developing tailored quantum hardware and algorithms to simulate them is an outstanding challenge in the rapidly evolving field of quantum simulation. Here we take an approach where gauge fields, discretized in spacetime, are represented by qudits and are time-evolved in Trotter steps with multiqudit quantum… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.15541v2-abstract-full').style.display = 'inline'; document.getElementById('2203.15541v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.15541v2-abstract-full" style="display: none;"> Non-abelian gauge theories underlie our understanding of fundamental forces in nature, and developing tailored quantum hardware and algorithms to simulate them is an outstanding challenge in the rapidly evolving field of quantum simulation. Here we take an approach where gauge fields, discretized in spacetime, are represented by qudits and are time-evolved in Trotter steps with multiqudit quantum gates. This maps naturally and hardware-efficiently to an architecture based on Rydberg tweezer arrays, where long-lived internal atomic states represent qudits, and the required quantum gates are performed as holonomic operations supported by a Rydberg blockade mechanism. We illustrate our proposal for a minimal digitization of SU(2) gauge fields, demonstrating a significant reduction in circuit depth and gate errors in comparison to a traditional qubit-based approach, which puts simulations of non-abelian gauge theories within reach of NISQ devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.15541v2-abstract-full').style.display = 'none'; document.getElementById('2203.15541v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5+6 pages, 3+5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 129, 160501 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.11374">arXiv:2203.11374</a> <span> [<a href="https://arxiv.org/pdf/2203.11374">pdf</a>, <a href="https://arxiv.org/format/2203.11374">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s42254-022-00535-2">10.1038/s42254-022-00535-2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The randomized measurement toolbox </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Flammia%2C+S+T">Steven T. Flammia</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">Hsin-Yuan Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Kueng%2C+R">Richard Kueng</a>, <a href="/search/quant-ph?searchtype=author&query=Preskill%2C+J">John Preskill</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.11374v1-abstract-short" style="display: inline;"> Increasingly sophisticated programmable quantum simulators and quantum computers are opening unprecedented opportunities for exploring and exploiting the properties of highly entangled complex quantum systems. The complexity of large quantum systems is the source of their power, but also makes them difficult to control precisely or characterize accurately using measured classical data. We review r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.11374v1-abstract-full').style.display = 'inline'; document.getElementById('2203.11374v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.11374v1-abstract-full" style="display: none;"> Increasingly sophisticated programmable quantum simulators and quantum computers are opening unprecedented opportunities for exploring and exploiting the properties of highly entangled complex quantum systems. The complexity of large quantum systems is the source of their power, but also makes them difficult to control precisely or characterize accurately using measured classical data. We review recently developed protocols for probing the properties of complex many-qubit systems using measurement schemes that are practical using today's quantum platforms. In all these protocols, a quantum state is repeatedly prepared and measured in a randomly chosen basis; then a classical computer processes the measurement outcomes to estimate the desired property. The randomization of the measurement procedure has distinct advantages; for example, a single data set can be employed multiple times to pursue a variety of applications, and imperfections in the measurements are mapped to a simplified noise model that can more easily be mitigated. We discuss a range of use cases that have already been realized in quantum devices, including Hamiltonian simulation tasks, probes of quantum chaos, measurements of nonlocal order parameters, and comparison of quantum states produced in distantly separated laboratories. By providing a workable method for translating a complex quantum state into a succinct classical representation that preserves a rich variety of relevant physical properties, the randomized measurement toolbox strengthens our ability to grasp and control the quantum world. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.11374v1-abstract-full').style.display = 'none'; document.getElementById('2203.11374v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Review Physics (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.07395">arXiv:2203.07395</a> <span> [<a href="https://arxiv.org/pdf/2203.07395">pdf</a>, <a href="https://arxiv.org/format/2203.07395">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Towards experimental classical verification of quantum computation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Stricker%2C+R">Roman Stricker</a>, <a href="/search/quant-ph?searchtype=author&query=Carrasco%2C+J">Jose Carrasco</a>, <a href="/search/quant-ph?searchtype=author&query=Ringbauer%2C+M">Martin Ringbauer</a>, <a href="/search/quant-ph?searchtype=author&query=Postler%2C+L">Lukas Postler</a>, <a href="/search/quant-ph?searchtype=author&query=Meth%2C+M">Michael Meth</a>, <a href="/search/quant-ph?searchtype=author&query=Edmunds%2C+C">Claire Edmunds</a>, <a href="/search/quant-ph?searchtype=author&query=Schindler%2C+P">Philipp Schindler</a>, <a href="/search/quant-ph?searchtype=author&query=Blatt%2C+R">Rainer Blatt</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Kraus%2C+B">Barbara Kraus</a>, <a href="/search/quant-ph?searchtype=author&query=Monz%2C+T">Thomas Monz</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.07395v1-abstract-short" style="display: inline;"> With today's quantum processors venturing into regimes beyond the capabilities of classical devices [1-3], we face the challenge to verify that these devices perform as intended, even when we cannot check their results on classical computers [4,5]. In a recent breakthrough in computer science [6-8], a protocol was developed that allows the verification of the output of a computation performed by a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.07395v1-abstract-full').style.display = 'inline'; document.getElementById('2203.07395v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.07395v1-abstract-full" style="display: none;"> With today's quantum processors venturing into regimes beyond the capabilities of classical devices [1-3], we face the challenge to verify that these devices perform as intended, even when we cannot check their results on classical computers [4,5]. In a recent breakthrough in computer science [6-8], a protocol was developed that allows the verification of the output of a computation performed by an untrusted quantum device based only on classical resources. Here, we follow these ideas, and demonstrate in a first, proof-of-principle experiment a verification protocol using only classical means on a small trapped-ion quantum processor. We contrast this to verification protocols, which require trust and detailed hardware knowledge, as in gate-level benchmarking [9], or additional quantum resources in case we do not have access to or trust in the device to be tested [5]. While our experimental demonstration uses a simplified version [10] of Mahadev's protocol [6] we demonstrate the necessary steps for verifying fully untrusted devices. A scaled-up version of our protocol will allow for classical verification, requiring no hardware access or detailed knowledge of the tested device. Its security relies on post-quantum secure trapdoor functions within an interactive proof [11]. The conceptually straightforward, but technologically challenging scaled-up version of the interactive proofs, considered here, can be used for a variety of additional tasks such as verifying quantum advantage [8], generating [12] and certifying quantum randomness [7], or composable remote state preparation [13]. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.07395v1-abstract-full').style.display = 'none'; document.getElementById('2203.07395v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 8 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.11113">arXiv:2110.11113</a> <span> [<a href="https://arxiv.org/pdf/2110.11113">pdf</a>, <a href="https://arxiv.org/format/2110.11113">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> </div> </div> <p class="title is-5 mathjax"> Quantum Chaos and Universal Trotterisation Behaviours in Digital Quantum Simulations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kargi%2C+C">Cahit Kargi</a>, <a href="/search/quant-ph?searchtype=author&query=Dehollain%2C+J+P">Juan Pablo Dehollain</a>, <a href="/search/quant-ph?searchtype=author&query=Sieberer%2C+L+M">Lukas M. Sieberer</a>, <a href="/search/quant-ph?searchtype=author&query=Henriques%2C+F">Fabio Henriques</a>, <a href="/search/quant-ph?searchtype=author&query=Olsacher%2C+T">Tobias Olsacher</a>, <a href="/search/quant-ph?searchtype=author&query=Hauke%2C+P">Philipp Hauke</a>, <a href="/search/quant-ph?searchtype=author&query=Heyl%2C+M">Markus Heyl</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Langford%2C+N+K">Nathan K. Langford</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.11113v3-abstract-short" style="display: inline;"> Digital quantum simulation (DQS) is one of the most promising paths for achieving first useful real-world applications for quantum processors. Yet even assuming rapid progress in device engineering and development of fault-tolerant quantum processors, algorithmic resource optimisation will long remain crucial to exploit their full power. Currently, Trotterisation provides state-of-the-art resource… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.11113v3-abstract-full').style.display = 'inline'; document.getElementById('2110.11113v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.11113v3-abstract-full" style="display: none;"> Digital quantum simulation (DQS) is one of the most promising paths for achieving first useful real-world applications for quantum processors. Yet even assuming rapid progress in device engineering and development of fault-tolerant quantum processors, algorithmic resource optimisation will long remain crucial to exploit their full power. Currently, Trotterisation provides state-of-the-art resource scaling. And recent theoretical studies of Trotterised Ising models suggest that even better performance than expected may be possible up to a distinct breakdown threshold in empirical performance. Here, we study multiple paradigmatic DQS models with experimentally realisable Trotterisations, and evidence the universality of a range of Trotterisation performance behaviours, including not only the threshold, but also new features in the pre-threshold regime that is most important for practical applications. In each model, we observe a distinct Trotterisation threshold shared across widely varying performance signatures; we further show that an onset of quantum chaotic dynamics causes the performance breakdown and is directly induced by digitisation errors. In the important pre-threshold regime, we are able to identify new distinct regimes displaying qualitatively different quasiperiodic performance behaviours, and show analytic behaviour for properly defined operational Trotter errors. Our results rely crucially on diverse new analytical tools, and provide a previously missing unified picture of Trotterisation behaviour across local observables, the global quantum state, and the full Trotterised unitary. This work provides new insights and tools for addressing important questions about the algorithm performance and underlying theoretical principles of sufficiently complex Trotterisation-based DQS, that will help in extracting maximum simulation power from future quantum processors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.11113v3-abstract-full').style.display = 'none'; document.getElementById('2110.11113v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">48 pages, 22 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.03913">arXiv:2110.03913</a> <span> [<a href="https://arxiv.org/pdf/2110.03913">pdf</a>, <a href="https://arxiv.org/format/2110.03913">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.22331/q-2022-04-27-702">10.22331/q-2022-04-27-702 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Entanglement Spectroscopy and probing the Li-Haldane Conjecture in Topological Quantum Matter </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Sundar%2C+B">Bhuvanesh Sundar</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.03913v2-abstract-short" style="display: inline;"> Topological phases are characterized by their entanglement properties, which is manifest in a direct relation between entanglement spectra and edge states discovered by Li and Haldane. We propose to leverage the power of synthetic quantum systems for measuring entanglement via the Entanglement Hamiltonian to probe this relationship experimentally. This is made possible by exploiting the quasi-loca… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.03913v2-abstract-full').style.display = 'inline'; document.getElementById('2110.03913v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.03913v2-abstract-full" style="display: none;"> Topological phases are characterized by their entanglement properties, which is manifest in a direct relation between entanglement spectra and edge states discovered by Li and Haldane. We propose to leverage the power of synthetic quantum systems for measuring entanglement via the Entanglement Hamiltonian to probe this relationship experimentally. This is made possible by exploiting the quasi-local structure of Entanglement Hamiltonians. The feasibility of this proposal is illustrated for two paradigmatic examples realizable with current technology, an integer quantum Hall state of non-interacting fermions on a 2D lattice and a symmetry protected topological state of interacting fermions on a 1D chain. Our results pave the road towards an experimental identification of topological order in strongly correlated quantum many-body systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.03913v2-abstract-full').style.display = 'none'; document.getElementById('2110.03913v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11+11 pages, 7+3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum 6, 702 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.12378">arXiv:2108.12378</a> <span> [<a href="https://arxiv.org/pdf/2108.12378">pdf</a>, <a href="https://arxiv.org/format/2108.12378">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.3.020304">10.1103/PRXQuantum.3.020304 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Probing infinite many-body quantum systems with finite-size quantum simulators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kuzmin%2C+V">Viacheslav Kuzmin</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Pastori%2C+L">Lorenzo Pastori</a>, <a href="/search/quant-ph?searchtype=author&query=Celi%2C+A">Alessio Celi</a>, <a href="/search/quant-ph?searchtype=author&query=Baranov%2C+M">Mikhail Baranov</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.12378v3-abstract-short" style="display: inline;"> Experimental studies of synthetic quantum matter are necessarily restricted to approximate ground states prepared on finite-size quantum simulators. In general, this limits their reliability for strongly correlated systems, for instance, in the vicinity of a quantum phase transition (QPT). Here, we propose a protocol that makes optimal use of a given finite-size simulator by directly preparing, on… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.12378v3-abstract-full').style.display = 'inline'; document.getElementById('2108.12378v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.12378v3-abstract-full" style="display: none;"> Experimental studies of synthetic quantum matter are necessarily restricted to approximate ground states prepared on finite-size quantum simulators. In general, this limits their reliability for strongly correlated systems, for instance, in the vicinity of a quantum phase transition (QPT). Here, we propose a protocol that makes optimal use of a given finite-size simulator by directly preparing, on its bulk region, a mixed state representing the reduced density operator of the translation-invariant infinite-sized system of interest. This protocol is based on coherent evolution with a local deformation of the system Hamiltonian. For systems of free fermions in one and two spatial dimensions, we illustrate and explain the underlying physics, which consists of quasi-particle transport towards the system's boundaries while retaining the bulk "vacuum". For the example of a non-integrable extended Su-Schrieffer-Heeger model, we demonstrate that our protocol enables a more accurate study of QPTs. In addition, we demonstrate the protocol for an interacting spinful Fermi-Hubbard model with doping for 1D chains and a small two-leg ladder, where the initial state is a random superposition of energetically low-lying states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.12378v3-abstract-full').style.display = 'none'; document.getElementById('2108.12378v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.11856">arXiv:2108.11856</a> <span> [<a href="https://arxiv.org/pdf/2108.11856">pdf</a>, <a href="https://arxiv.org/format/2108.11856">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.22331/q-2022-06-07-731">10.22331/q-2022-06-07-731 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Topological phonons in arrays of ultracold dipolar particles </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Di+Liberto%2C+M">Marco Di Liberto</a>, <a href="/search/quant-ph?searchtype=author&query=Kruckenhauser%2C+A">Andreas Kruckenhauser</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Baranov%2C+M+A">Mikhail A. Baranov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.11856v2-abstract-short" style="display: inline;"> The notion of topology in physical systems is associated with the existence of a nonlocal ordering that is insensitive to a large class of perturbations. This brings robustness to the behaviour of the system and can serve as a ground for developing new fault-tolerant applications. We discuss how to design and study a large variety of topology-related phenomena for phonon-like collective modes in a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.11856v2-abstract-full').style.display = 'inline'; document.getElementById('2108.11856v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.11856v2-abstract-full" style="display: none;"> The notion of topology in physical systems is associated with the existence of a nonlocal ordering that is insensitive to a large class of perturbations. This brings robustness to the behaviour of the system and can serve as a ground for developing new fault-tolerant applications. We discuss how to design and study a large variety of topology-related phenomena for phonon-like collective modes in arrays of ultracold polarized dipolar particles. These modes are coherently propagating vibrational excitations, corresponding to oscillations of particles around their equilibrium positions, which exist in the regime where long-range interactions dominate over single-particle motion. We demonstrate that such systems offer a distinct and versatile tool to investigate a wide range of topological effects in a single experimental setup with a chosen underlying crystal structure by simply controlling the anisotropy of the interactions via the orientation of the external polarizing field. Our results show that arrays of dipolar particles provide a promising unifying platform to investigate topological phenomena with phononic modes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.11856v2-abstract-full').style.display = 'none'; document.getElementById('2108.11856v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages + 9 figures and 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum 6, 731 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.01860">arXiv:2107.01860</a> <span> [<a href="https://arxiv.org/pdf/2107.01860">pdf</a>, <a href="https://arxiv.org/format/2107.01860">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-022-04435-4">10.1038/s41586-022-04435-4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimal metrology with programmable quantum sensors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Marciniak%2C+C+D">Christian D. Marciniak</a>, <a href="/search/quant-ph?searchtype=author&query=Feldker%2C+T">Thomas Feldker</a>, <a href="/search/quant-ph?searchtype=author&query=Pogorelov%2C+I">Ivan Pogorelov</a>, <a href="/search/quant-ph?searchtype=author&query=Kaubruegger%2C+R">Raphael Kaubruegger</a>, <a href="/search/quant-ph?searchtype=author&query=Vasilyev%2C+D+V">Denis V. Vasilyev</a>, <a href="/search/quant-ph?searchtype=author&query=van+Bijnen%2C+R">Rick van Bijnen</a>, <a href="/search/quant-ph?searchtype=author&query=Schindler%2C+P">Philipp Schindler</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Blatt%2C+R">Rainer Blatt</a>, <a href="/search/quant-ph?searchtype=author&query=Monz%2C+T">Thomas Monz</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.01860v2-abstract-short" style="display: inline;"> Quantum sensors are an established technology that has created new opportunities for precision sensing across the breadth of science. Using entanglement for quantum-enhancement will allow us to construct the next generation of sensors that can approach the fundamental limits of precision allowed by quantum physics. However, determining how state-of-the-art sensing platforms may be used to converge… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.01860v2-abstract-full').style.display = 'inline'; document.getElementById('2107.01860v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.01860v2-abstract-full" style="display: none;"> Quantum sensors are an established technology that has created new opportunities for precision sensing across the breadth of science. Using entanglement for quantum-enhancement will allow us to construct the next generation of sensors that can approach the fundamental limits of precision allowed by quantum physics. However, determining how state-of-the-art sensing platforms may be used to converge to these ultimate limits is an outstanding challenge. In this work we merge concepts from the field of quantum information processing with metrology, and successfully implement experimentally a *programmable quantum sensor* operating close to the fundamental limits imposed by the laws of quantum mechanics. We achieve this by using low-depth, parametrized quantum circuits implementing optimal input states and measurement operators for a sensing task on a trapped ion experiment. With 26 ions, we approach the fundamental sensing limit up to a factor of 1.45(1), outperforming conventional spin-squeezing with a factor of 1.87(3). Our approach reduces the number of averages to reach a given Allan deviation by a factor of 1.59(6) compared to traditional methods not employing entanglement-enabled protocols. We further perform on-device quantum-classical feedback optimization to `self-calibrate' the programmable quantum sensor with comparable performance. This ability illustrates that this next generation of quantum sensor can be employed without prior knowledge of the device or its noise environment. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.01860v2-abstract-full').style.display = 'none'; document.getElementById('2107.01860v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main: 10 pages including Methods, 4 figures. Supplementary Material: 6 pages, 2 figures, separate references</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.15530">arXiv:2106.15530</a> <span> [<a href="https://arxiv.org/pdf/2106.15530">pdf</a>, <a href="https://arxiv.org/format/2106.15530">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevX.12.011018">10.1103/PhysRevX.12.011018 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Probing many-body quantum chaos with quantum simulators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Joshi%2C+L+K">Lata Kh Joshi</a>, <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Vikram%2C+A">Amit Vikram</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Galitski%2C+V">Victor Galitski</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.15530v2-abstract-short" style="display: inline;"> The spectral form factor (SFF), characterizing statistics of energy eigenvalues, is a key diagnostic of many-body quantum chaos. In addition, partial spectral form factors (PSFFs) can be defined which refer to subsystems of the many-body system. They provide unique insights into energy eigenstate statistics of many-body systems, as we show in an analysis on the basis of random matrix theory and of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.15530v2-abstract-full').style.display = 'inline'; document.getElementById('2106.15530v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.15530v2-abstract-full" style="display: none;"> The spectral form factor (SFF), characterizing statistics of energy eigenvalues, is a key diagnostic of many-body quantum chaos. In addition, partial spectral form factors (PSFFs) can be defined which refer to subsystems of the many-body system. They provide unique insights into energy eigenstate statistics of many-body systems, as we show in an analysis on the basis of random matrix theory and of the eigenstate thermalization hypothesis. We propose a protocol that allows the measurement of the SFF and PSFFs in quantum many-body spin models, within the framework of randomized measurements. Aimed to probe dynamical properties of quantum many-body systems, our scheme employs statistical correlations of local random operations which are applied at different times in a single experiment. Our protocol provides a unified testbed to probe many-body quantum chaotic behavior, thermalization and many-body localization in closed quantum systems which we illustrate with numerical simulations for Hamiltonian and Floquet many-body spin-systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.15530v2-abstract-full').style.display = 'none'; document.getElementById('2106.15530v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16+14 pages, 14 figures. The presentation throughout the paper is improved, without any change in the core content and results. New figure and appendix added. Matches with the published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. X 12, 011018 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.04317">arXiv:2105.04317</a> <span> [<a href="https://arxiv.org/pdf/2105.04317">pdf</a>, <a href="https://arxiv.org/format/2105.04317">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.127.170501">10.1103/PhysRevLett.127.170501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum Variational Learning of the Entanglement Hamiltonian </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Sundar%2C+B">Bhuvanesh Sundar</a>, <a href="/search/quant-ph?searchtype=author&query=Zache%2C+T+V">Torsten V. Zache</a>, <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Dalmonte%2C+M">Marcello Dalmonte</a>, <a href="/search/quant-ph?searchtype=author&query=van+Bijnen%2C+R">Rick van Bijnen</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.04317v2-abstract-short" style="display: inline;"> Learning the structure of the entanglement Hamiltonian (EH) is central to characterizing quantum many-body states in analog quantum simulation. We describe a protocol where spatial deformations of the many-body Hamiltonian, physically realized on the quantum device, serve as an efficient variational ansatz for a local EH. Optimal variational parameters are determined in a feedback loop, involving… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.04317v2-abstract-full').style.display = 'inline'; document.getElementById('2105.04317v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.04317v2-abstract-full" style="display: none;"> Learning the structure of the entanglement Hamiltonian (EH) is central to characterizing quantum many-body states in analog quantum simulation. We describe a protocol where spatial deformations of the many-body Hamiltonian, physically realized on the quantum device, serve as an efficient variational ansatz for a local EH. Optimal variational parameters are determined in a feedback loop, involving quench dynamics with the deformed Hamiltonian as a quantum processing step, and classical optimization. We simulate the protocol for the ground state of Fermi-Hubbard models in quasi-1D geometries, finding excellent agreement of the EH with Bisognano-Wichmann predictions. Subsequent on-device spectroscopy enables a direct measurement of the entanglement spectrum, which we illustrate for a Fermi Hubbard model in a topological phase. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.04317v2-abstract-full').style.display = 'none'; document.getElementById('2105.04317v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 7 figures; updated to PRL version; Figure 4 updated, conclusions unchanged</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 127, 170501(2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2103.07443">arXiv:2103.07443</a> <span> [<a href="https://arxiv.org/pdf/2103.07443">pdf</a>, <a href="https://arxiv.org/format/2103.07443">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-021-00487-y">10.1038/s41534-021-00487-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Symmetry-resolved entanglement detection using partial transpose moments </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Neven%2C+A">Antoine Neven</a>, <a href="/search/quant-ph?searchtype=author&query=Carrasco%2C+J">Jose Carrasco</a>, <a href="/search/quant-ph?searchtype=author&query=Vitale%2C+V">Vittorio Vitale</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Dalmonte%2C+M">Marcello Dalmonte</a>, <a href="/search/quant-ph?searchtype=author&query=Calabrese%2C+P">Pasquale Calabrese</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Kueng%2C+R">Richard Kueng</a>, <a href="/search/quant-ph?searchtype=author&query=Kraus%2C+B">Barbara Kraus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2103.07443v1-abstract-short" style="display: inline;"> We propose an ordered set of experimentally accessible conditions for detecting entanglement in mixed states. The $k$-th condition involves comparing moments of the partially transposed density operator up to order $k$. Remarkably, the union of all moment inequalities reproduces the Peres-Horodecki criterion for detecting entanglement. Our empirical studies highlight that the first four conditions… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.07443v1-abstract-full').style.display = 'inline'; document.getElementById('2103.07443v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2103.07443v1-abstract-full" style="display: none;"> We propose an ordered set of experimentally accessible conditions for detecting entanglement in mixed states. The $k$-th condition involves comparing moments of the partially transposed density operator up to order $k$. Remarkably, the union of all moment inequalities reproduces the Peres-Horodecki criterion for detecting entanglement. Our empirical studies highlight that the first four conditions already detect mixed state entanglement reliably in a variety of quantum architectures. Exploiting symmetries can help to further improve their detection capabilities. We also show how to estimate moment inequalities based on local random measurements of single state copies (classical shadows) and derive statistically sound confidence intervals as a function of the number of performed measurements. Our analysis includes the experimentally relevant situation of drifting sources, i.e. non-identical, but independent, state copies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.07443v1-abstract-full').style.display = 'none'; document.getElementById('2103.07443v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11+11 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Npj Quantum Inf. 7, 152 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.13524">arXiv:2102.13524</a> <span> [<a href="https://arxiv.org/pdf/2102.13524">pdf</a>, <a href="https://arxiv.org/format/2102.13524">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.127.200503">10.1103/PhysRevLett.127.200503 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Importance sampling of randomized measurements for probing entanglement </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Rath%2C+A">Aniket Rath</a>, <a href="/search/quant-ph?searchtype=author&query=van+Bijnen%2C+R">Rick van Bijnen</a>, <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.13524v2-abstract-short" style="display: inline;"> We show that combining randomized measurement protocols with importance sampling allows for characterizing entanglement in significantly larger quantum systems and in a more efficient way than in previous work. A drastic reduction of statistical errors is obtained using classical techniques of machine-learning and tensor networks using partial information on the quantum state. In present experimen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.13524v2-abstract-full').style.display = 'inline'; document.getElementById('2102.13524v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.13524v2-abstract-full" style="display: none;"> We show that combining randomized measurement protocols with importance sampling allows for characterizing entanglement in significantly larger quantum systems and in a more efficient way than in previous work. A drastic reduction of statistical errors is obtained using classical techniques of machine-learning and tensor networks using partial information on the quantum state. In present experimental settings of engineered many-body quantum systems this effectively doubles the (sub-)system sizes for which entanglement can be measured. In particular, we show an exponential reduction of the required number of measurements to estimate the purity of product states and GHZ states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.13524v2-abstract-full').style.display = 'none'; document.getElementById('2102.13524v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6+6 pages, 3+4 figures, accepted version. Code available at https://github.com/bvermersch/RandomMeas</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 127, 200503 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.05927">arXiv:2102.05927</a> <span> [<a href="https://arxiv.org/pdf/2102.05927">pdf</a>, <a href="https://arxiv.org/format/2102.05927">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.2.010102">10.1103/PRXQuantum.2.010102 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Theoretical and Experimental Perspectives of Quantum Verification </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Carrasco%2C+J">Jose Carrasco</a>, <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Kraus%2C+B">Barbara Kraus</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.05927v2-abstract-short" style="display: inline;"> In this perspective we discuss verification of quantum devices in the context of specific examples, formulated as proposed experiments. Our first example is verification of analog quantum simulators as Hamiltonian learning, where the input Hamiltonian as design goal is compared with the parent Hamiltonian for the quantum states prepared on the device. The second example discusses cross-device veri… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.05927v2-abstract-full').style.display = 'inline'; document.getElementById('2102.05927v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.05927v2-abstract-full" style="display: none;"> In this perspective we discuss verification of quantum devices in the context of specific examples, formulated as proposed experiments. Our first example is verification of analog quantum simulators as Hamiltonian learning, where the input Hamiltonian as design goal is compared with the parent Hamiltonian for the quantum states prepared on the device. The second example discusses cross-device verification on the quantum level, i.e. by comparing quantum states prepared on different quantum devices. We focus in particular on protocols using randomized measurements, and we propose establishing a central data repository, where existing experimental devices and platforms can be compared. In our final example, we address verification of the output of a quantum device from a computer science perspective, addressing the question of how a user of a quantum processor can be certain about the correctness of its output, and propose minimal demonstrations on present day devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.05927v2-abstract-full').style.display = 'none'; document.getElementById('2102.05927v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 2, 010102 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.05593">arXiv:2102.05593</a> <span> [<a href="https://arxiv.org/pdf/2102.05593">pdf</a>, <a href="https://arxiv.org/format/2102.05593">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevX.11.041045">10.1103/PhysRevX.11.041045 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum Variational Optimization of Ramsey Interferometry and Atomic Clocks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kaubruegger%2C+R">Raphael Kaubruegger</a>, <a href="/search/quant-ph?searchtype=author&query=Vasilyev%2C+D+V">Denis V. Vasilyev</a>, <a href="/search/quant-ph?searchtype=author&query=Schulte%2C+M">Marius Schulte</a>, <a href="/search/quant-ph?searchtype=author&query=Hammerer%2C+K">Klemens Hammerer</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.05593v2-abstract-short" style="display: inline;"> We discuss quantum variational optimization of Ramsey interferometry with ensembles of $N$ entangled atoms, and its application to atomic clocks based on a Bayesian approach to phase estimation. We identify best input states and generalized measurements within a variational approximation for the corresponding entangling and decoding quantum circuits. These circuits are built from basic quantum ope… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.05593v2-abstract-full').style.display = 'inline'; document.getElementById('2102.05593v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.05593v2-abstract-full" style="display: none;"> We discuss quantum variational optimization of Ramsey interferometry with ensembles of $N$ entangled atoms, and its application to atomic clocks based on a Bayesian approach to phase estimation. We identify best input states and generalized measurements within a variational approximation for the corresponding entangling and decoding quantum circuits. These circuits are built from basic quantum operations available for the particular sensor platform, such as one-axis twisting, or finite range interactions. Optimization is defined relative to a cost function, which in the present study is the Bayesian mean square error of the estimated phase for a given prior distribution, i.e. we optimize for a finite dynamic range of the interferometer. In analogous variational optimizations of optical atomic clocks, we use the Allan deviation for a given Ramsey interrogation time as the relevant cost function for the long-term instability. Remarkably, even low-depth quantum circuits yield excellent results that closely approach the fundamental quantum limits for optimal Ramsey interferometry and atomic clocks. The quantum metrological schemes identified here are readily applicable to atomic clocks based on optical lattices, tweezer arrays, or trapped ions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.05593v2-abstract-full').style.display = 'none'; document.getElementById('2102.05593v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 13 Figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.07814">arXiv:2101.07814</a> <span> [<a href="https://arxiv.org/pdf/2101.07814">pdf</a>, <a href="https://arxiv.org/format/2101.07814">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.21468/SciPostPhys.12.3.106">10.21468/SciPostPhys.12.3.106 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Symmetry-resolved dynamical purification in synthetic quantum matter </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Vitale%2C+V">Vittorio Vitale</a>, <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Kueng%2C+R">Richard Kueng</a>, <a href="/search/quant-ph?searchtype=author&query=Neven%2C+A">Antoine Neven</a>, <a href="/search/quant-ph?searchtype=author&query=Carrasco%2C+J">Jose Carrasco</a>, <a href="/search/quant-ph?searchtype=author&query=Kraus%2C+B">Barbara Kraus</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Calabrese%2C+P">Pasquale Calabrese</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Benoit Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Dalmonte%2C+M">Marcello Dalmonte</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.07814v3-abstract-short" style="display: inline;"> When a quantum system initialized in a product state is subjected to either coherent or incoherent dynamics, the entropy of any of its connected partitions generically increases as a function of time, signalling the inevitable spreading of (quantum) information throughout the system. Here, we show that, in the presence of continuous symmetries and under ubiquitous experimental conditions, symmetry… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.07814v3-abstract-full').style.display = 'inline'; document.getElementById('2101.07814v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.07814v3-abstract-full" style="display: none;"> When a quantum system initialized in a product state is subjected to either coherent or incoherent dynamics, the entropy of any of its connected partitions generically increases as a function of time, signalling the inevitable spreading of (quantum) information throughout the system. Here, we show that, in the presence of continuous symmetries and under ubiquitous experimental conditions, symmetry-resolved information spreading is inhibited due to the competition of coherent and incoherent dynamics: in given quantum number sectors, entropy decreases as a function of time, signalling dynamical purification. Such dynamical purification bridges between two distinct short and intermediate time regimes, characterized by a log-volume and log-area entropy law, respectively. It is generic to symmetric quantum evolution, and as such occurs for different partition geometry and topology, and classes of (local) Liouville dynamics. We then develop a protocol to measure symmetry-resolved entropies and negativities in synthetic quantum systems based on the random unitary toolbox, and demonstrate the generality of dynamical purification using experimental data from trapped ion experiments [Brydges et al., Science 364, 260 (2019)]. Our work shows that symmetry plays a key role as a magnifying glass to characterize many-body dynamics in open quantum systems, and, in particular, in noisy-intermediate scale quantum devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.07814v3-abstract-full').style.display = 'none'; document.getElementById('2101.07814v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">41 pages, 11 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> SciPost Phys. 12, 106 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.09000">arXiv:2009.09000</a> <span> [<a href="https://arxiv.org/pdf/2009.09000">pdf</a>, <a href="https://arxiv.org/format/2009.09000">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-021-01260-w">10.1038/s41567-021-01260-w <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Entanglement Hamiltonian Tomography in Quantum Simulation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=van+Bijnen%2C+R">Rick van Bijnen</a>, <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2009.09000v2-abstract-short" style="display: inline;"> Entanglement is the crucial ingredient of quantum many-body physics, and characterizing and quantifying entanglement in closed system dynamics of quantum simulators is an outstanding challenge in today's era of intermediate scale quantum devices. Here we discuss an efficient tomographic protocol for reconstructing reduced density matrices and entanglement spectra for spin systems. The key step is… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.09000v2-abstract-full').style.display = 'inline'; document.getElementById('2009.09000v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.09000v2-abstract-full" style="display: none;"> Entanglement is the crucial ingredient of quantum many-body physics, and characterizing and quantifying entanglement in closed system dynamics of quantum simulators is an outstanding challenge in today's era of intermediate scale quantum devices. Here we discuss an efficient tomographic protocol for reconstructing reduced density matrices and entanglement spectra for spin systems. The key step is a parametrization of the reduced density matrix in terms of an entanglement Hamiltonian involving only quasi local few-body terms. This ansatz is fitted to, and can be independently verified from, a small number of randomised measurements. The ansatz is suggested by Conformal Field Theory in quench dynamics, and via the Bisognano-Wichmann theorem for ground states. Not only does the protocol provide a testbed for these theories in quantum simulators, it is also applicable outside these regimes. We show the validity and efficiency of the protocol for a long-range Ising model in 1D using numerical simulations. Furthermore, by analyzing data from $10$ and $20$ ion quantum simulators [Brydges \textit{et al.}, Science, 2019], we demonstrate measurement of the evolution of the entanglement spectrum in quench dynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.09000v2-abstract-full').style.display = 'none'; document.getElementById('2009.09000v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages (6 pages supplemental information), 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Physics. 17, 936-942 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.11389">arXiv:2008.11389</a> <span> [<a href="https://arxiv.org/pdf/2008.11389">pdf</a>, <a href="https://arxiv.org/format/2008.11389">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.1.020316">10.1103/PRXQuantum.1.020316 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Scalable and Parallel Tweezer Gates for Quantum Computing with Long Ion Strings </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Olsacher%2C+T">Tobias Olsacher</a>, <a href="/search/quant-ph?searchtype=author&query=Postler%2C+L">Lukas Postler</a>, <a href="/search/quant-ph?searchtype=author&query=Schindler%2C+P">Philipp Schindler</a>, <a href="/search/quant-ph?searchtype=author&query=Monz%2C+T">Thomas Monz</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Sieberer%2C+L+M">Lukas M. Sieberer</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.11389v2-abstract-short" style="display: inline;"> Trapped-ion quantum computers have demonstrated high-performance gate operations in registers of about ten qubits. However, scaling up and parallelizing quantum computations with long one-dimensional (1D) ion strings is an outstanding challenge due to the global nature of the motional modes of the ions which mediate qubit-qubit couplings. Here, we devise methods to implement scalable and parallel… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.11389v2-abstract-full').style.display = 'inline'; document.getElementById('2008.11389v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.11389v2-abstract-full" style="display: none;"> Trapped-ion quantum computers have demonstrated high-performance gate operations in registers of about ten qubits. However, scaling up and parallelizing quantum computations with long one-dimensional (1D) ion strings is an outstanding challenge due to the global nature of the motional modes of the ions which mediate qubit-qubit couplings. Here, we devise methods to implement scalable and parallel entangling gates by using engineered localized phonon modes. We propose to tailor such localized modes by tuning the local potential of individual ions with programmable optical tweezers. Localized modes of small subsets of qubits form the basis to perform entangling gates on these subsets in parallel. We demonstrate the inherent scalability of this approach by presenting analytical and numerical results for long 1D ion chains and even for infinite chains of uniformly spaced ions. Furthermore, we show that combining our methods with optimal coherent control techniques allows to realize maximally dense universal parallelized quantum circuits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.11389v2-abstract-full').style.display = 'none'; document.getElementById('2008.11389v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 12 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 1, 020316 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.09252">arXiv:2008.09252</a> <span> [<a href="https://arxiv.org/pdf/2008.09252">pdf</a>, <a href="https://arxiv.org/format/2008.09252">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.2.030334">10.1103/PRXQuantum.2.030334 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Towards simulating 2D effects in lattice gauge theories on a quantum computer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Paulson%2C+D">Danny Paulson</a>, <a href="/search/quant-ph?searchtype=author&query=Dellantonio%2C+L">Luca Dellantonio</a>, <a href="/search/quant-ph?searchtype=author&query=Haase%2C+J+F">Jan F. Haase</a>, <a href="/search/quant-ph?searchtype=author&query=Celi%2C+A">Alessio Celi</a>, <a href="/search/quant-ph?searchtype=author&query=Kan%2C+A">Angus Kan</a>, <a href="/search/quant-ph?searchtype=author&query=Jena%2C+A">Andrew Jena</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=van+Bijnen%2C+R">Rick van Bijnen</a>, <a href="/search/quant-ph?searchtype=author&query=Jansen%2C+K">Karl Jansen</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Muschik%2C+C+A">Christine A. Muschik</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.09252v2-abstract-short" style="display: inline;"> Gauge theories are the most successful theories for describing nature at its fundamental level, but obtaining analytical or numerical solutions often remains a challenge. We propose an experimental quantum simulation scheme to study ground state properties in two-dimensional quantum electrodynamics (2D QED) using existing quantum technology. The proposal builds on a formulation of lattice gauge th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.09252v2-abstract-full').style.display = 'inline'; document.getElementById('2008.09252v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.09252v2-abstract-full" style="display: none;"> Gauge theories are the most successful theories for describing nature at its fundamental level, but obtaining analytical or numerical solutions often remains a challenge. We propose an experimental quantum simulation scheme to study ground state properties in two-dimensional quantum electrodynamics (2D QED) using existing quantum technology. The proposal builds on a formulation of lattice gauge theories as effective spin models in arXiv:2006.14160, which reduces the number of qubits needed by eliminating redundant degrees of freedom and by using an efficient truncation scheme for the gauge fields. The latter endows our proposal with the perspective to take a well-controlled continuum limit. Our protocols allow in principle scaling up to large lattices and offer the perspective to connect the lattice simulation to low energy observable quantities, e.g. the hadron spectrum, in the continuum theory. By including both dynamical matter and a non-minimal gauge field truncation, we provide the novel opportunity to observe 2D effects on present-day quantum hardware. More specifically, we present two Variational Quantum Eigensolver (VQE) based protocols for the study of magnetic field effects, and for taking an important first step towards computing the running coupling of QED. For both instances, we include variational quantum circuits for qubit-based hardware, which we explicitly apply to trapped ion quantum computers. We simulate the proposed VQE experiments classically to calculate the required measurement budget under realistic conditions. While this feasibility analysis is done for trapped ions, our approach can be easily adapted to other platforms. The techniques presented here, combined with advancements in quantum hardware pave the way for reaching beyond the capabilities of classical simulations by extending our framework to include fermionic potentials or topological terms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.09252v2-abstract-full').style.display = 'none'; document.getElementById('2008.09252v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">26 pages, 12 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 2, 030334 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.00006">arXiv:2008.00006</a> <span> [<a href="https://arxiv.org/pdf/2008.00006">pdf</a>, <a href="https://arxiv.org/format/2008.00006">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.1.020311">10.1103/PRXQuantum.1.020311 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Programmable Quantum Annealing Architectures with Ising Quantum Wires </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+X">Xingze Qiu</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xiaopeng Li</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.00006v2-abstract-short" style="display: inline;"> Quantum annealing aims at solving optimization problems efficiently by preparing the ground state of an Ising spin-Hamiltonian quantum mechanically. A prerequisite of building a quantum annealer is the implementation of programmable long-range two-, three- or multi-spin Ising interactions. We discuss an architecture, where the required spin interactions are implemented via two-port, or in general… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.00006v2-abstract-full').style.display = 'inline'; document.getElementById('2008.00006v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.00006v2-abstract-full" style="display: none;"> Quantum annealing aims at solving optimization problems efficiently by preparing the ground state of an Ising spin-Hamiltonian quantum mechanically. A prerequisite of building a quantum annealer is the implementation of programmable long-range two-, three- or multi-spin Ising interactions. We discuss an architecture, where the required spin interactions are implemented via two-port, or in general multi-port quantum Ising wires connecting the spins of interest. This quantum annealing architecture of spins connected by Ising quantum wires can be realized by exploiting the three dimensional (3D) character of atomic platforms, including atoms in optical lattices and Rydberg tweezer arrays. The realization only requires engineering on-site terms and two-body interactions between nearest neighboring qubits. The locally coupled spin model on a 3D cubic lattice is sufficient to effectively produce arbitrary all-to-all coupled Ising Hamiltonians. We illustrate the approach for few spin devices solving Max-Cut and prime factorization problems, and discuss the potential scaling to large atom based systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.00006v2-abstract-full').style.display = 'none'; document.getElementById('2008.00006v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 November, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 July, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 1, 020311 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2007.06305">arXiv:2007.06305</a> <span> [<a href="https://arxiv.org/pdf/2007.06305">pdf</a>, <a href="https://arxiv.org/format/2007.06305">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.125.200501">10.1103/PhysRevLett.125.200501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Mixed-state entanglement from local randomized measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Kueng%2C+R">Richard Kueng</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">Hsin-Yuan Huang</a>, <a href="/search/quant-ph?searchtype=author&query=van+Bijnen%2C+R">Rick van Bijnen</a>, <a href="/search/quant-ph?searchtype=author&query=Kokail%2C+C">Christian Kokail</a>, <a href="/search/quant-ph?searchtype=author&query=Dalmonte%2C+M">Marcello Dalmonte</a>, <a href="/search/quant-ph?searchtype=author&query=Calabrese%2C+P">Pasquale Calabrese</a>, <a href="/search/quant-ph?searchtype=author&query=Kraus%2C+B">Barbara Kraus</a>, <a href="/search/quant-ph?searchtype=author&query=Preskill%2C+J">John Preskill</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2007.06305v2-abstract-short" style="display: inline;"> We propose a method for detecting bipartite entanglement in a many-body mixed state based on estimating moments of the partially transposed density matrix. The estimates are obtained by performing local random measurements on the state, followed by post-processing using the classical shadows framework. Our method can be applied to any quantum system with single-qubit control. We provide a detailed… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.06305v2-abstract-full').style.display = 'inline'; document.getElementById('2007.06305v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2007.06305v2-abstract-full" style="display: none;"> We propose a method for detecting bipartite entanglement in a many-body mixed state based on estimating moments of the partially transposed density matrix. The estimates are obtained by performing local random measurements on the state, followed by post-processing using the classical shadows framework. Our method can be applied to any quantum system with single-qubit control. We provide a detailed analysis of the required number of experimental runs, and demonstrate the protocol using existing experimental data [Brydges et al, Science 364, 260 (2019)]. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.06305v2-abstract-full').style.display = 'none'; document.getElementById('2007.06305v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 November, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 July, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5+10 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 125, 200501 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2006.00214">arXiv:2006.00214</a> <span> [<a href="https://arxiv.org/pdf/2006.00214">pdf</a>, <a href="https://arxiv.org/format/2006.00214">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.1.020302">10.1103/PRXQuantum.1.020302 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Monitoring Quantum Simulators via Quantum Non-Demolition Couplings to Atomic Clock Qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Vasilyev%2C+D+V">Denis V. Vasilyev</a>, <a href="/search/quant-ph?searchtype=author&query=Grankin%2C+A">Andrey Grankin</a>, <a href="/search/quant-ph?searchtype=author&query=Baranov%2C+M+A">Mikhail A. Baranov</a>, <a href="/search/quant-ph?searchtype=author&query=Sieberer%2C+L+M">Lukas M. Sieberer</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2006.00214v2-abstract-short" style="display: inline;"> We discuss monitoring the time evolution of an analog quantum simulator via a quantum non-demolition (QND) coupling to an auxiliary `clock' qubit. The QND variable of interest is the `energy' of the quantum many-body system, represented by the Hamiltonian of the quantum simulator. We describe a physical implementation of the underlying QND Hamiltonian for Rydberg atoms trapped in tweezer arrays us… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.00214v2-abstract-full').style.display = 'inline'; document.getElementById('2006.00214v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2006.00214v2-abstract-full" style="display: none;"> We discuss monitoring the time evolution of an analog quantum simulator via a quantum non-demolition (QND) coupling to an auxiliary `clock' qubit. The QND variable of interest is the `energy' of the quantum many-body system, represented by the Hamiltonian of the quantum simulator. We describe a physical implementation of the underlying QND Hamiltonian for Rydberg atoms trapped in tweezer arrays using laser dressing schemes for a broad class of spin models. As an application, we discuss a quantum protocol for measuring the spectral form factor of quantum many-body systems, where the aim is to identify signatures of ergodic vs. non-ergodic dynamics, which we illustrate for disordered 1D Heisenberg and Floquet spin models on Rydberg platforms. Our results also provide the physical ingredients for running quantum phase estimation protocols for measurement of energies, and preparation of energy eigenstates for a specified spectral resolution on an analog quantum simulator. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.00214v2-abstract-full').style.display = 'none'; document.getElementById('2006.00214v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 May, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 11 figures, accepted for publication in PRX Quantum</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 1, 020302 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2005.13543">arXiv:2005.13543</a> <span> [<a href="https://arxiv.org/pdf/2005.13543">pdf</a>, <a href="https://arxiv.org/format/2005.13543">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.126.050501">10.1103/PhysRevLett.126.050501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Many-body Chern number from statistical correlations of randomized measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cian%2C+Z">Ze-Pei Cian</a>, <a href="/search/quant-ph?searchtype=author&query=Dehghani%2C+H">Hossein Dehghani</a>, <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Beno卯t Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+G">Guanyu Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Barkeshli%2C+M">Maissam Barkeshli</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Hafezi%2C+M">Mohammad Hafezi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2005.13543v2-abstract-short" style="display: inline;"> One of the main topological invariants that characterizes several topologically-ordered phases is the many-body Chern number (MBCN). Paradigmatic examples include several fractional quantum Hall phases, which are expected to be realized in different atomic and photonic quantum platforms in the near future. Experimental measurement and numerical computation of this invariant is conventionally based… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.13543v2-abstract-full').style.display = 'inline'; document.getElementById('2005.13543v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2005.13543v2-abstract-full" style="display: none;"> One of the main topological invariants that characterizes several topologically-ordered phases is the many-body Chern number (MBCN). Paradigmatic examples include several fractional quantum Hall phases, which are expected to be realized in different atomic and photonic quantum platforms in the near future. Experimental measurement and numerical computation of this invariant is conventionally based on the linear-response techniques which require having access to a family of states, as a function of an external parameter, which is not suitable for many quantum simulators. Here, we propose an ancilla-free experimental scheme for the measurement of this invariant, without requiring any knowledge of the Hamiltonian. Specifically, we use the statistical correlations of randomized measurements to infer the MBCN of a wavefunction. Remarkably, our results apply to disk-like geometries that are more amenable to current quantum simulator architectures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.13543v2-abstract-full').style.display = 'none'; document.getElementById('2005.13543v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 May, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 126, 050501 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2002.09373">arXiv:2002.09373</a> <span> [<a href="https://arxiv.org/pdf/2002.09373">pdf</a>, <a href="https://arxiv.org/format/2002.09373">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevResearch.2.042013">10.1103/PhysRevResearch.2.042013 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum Simulation of 2D Quantum Chemistry in Optical Lattices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Arg%C3%BCello-Luengo%2C+J">Javier Arg眉ello-Luengo</a>, <a href="/search/quant-ph?searchtype=author&query=Gonz%C3%A1lez-Tudela%2C+A">Alejandro Gonz谩lez-Tudela</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+T">Tao Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Zoller%2C+P">Peter Zoller</a>, <a href="/search/quant-ph?searchtype=author&query=Cirac%2C+J+I">J. Ignacio Cirac</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2002.09373v1-abstract-short" style="display: inline;"> Benchmarking numerical methods in quantum chemistry is one of the key opportunities that quantum simulators can offer. Here, we propose an analog simulator for discrete 2D quantum chemistry models based on cold atoms in optical lattices. We first analyze how to simulate simple models, like the discrete versions of H and H$_2^+$, using a single fermionic atom. We then show that a single bosonic ato… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.09373v1-abstract-full').style.display = 'inline'; document.getElementById('2002.09373v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2002.09373v1-abstract-full" style="display: none;"> Benchmarking numerical methods in quantum chemistry is one of the key opportunities that quantum simulators can offer. Here, we propose an analog simulator for discrete 2D quantum chemistry models based on cold atoms in optical lattices. We first analyze how to simulate simple models, like the discrete versions of H and H$_2^+$, using a single fermionic atom. We then show that a single bosonic atom can mediate an effective Coulomb repulsion between two fermions, leading to the analog of molecular Hydrogen in two dimensions. We extend this approach to larger systems by introducing as many mediating atoms as fermions, and derive the effective repulsion law. In all cases, we analyze how the continuous limit is approached for increasing optical lattice sizes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.09373v1-abstract-full').style.display = 'none'; document.getElementById('2002.09373v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 7 figures. Supplementary material</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. 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