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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=Huang%2C+Z&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Huang%2C+Z&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Huang%2C+Z&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Huang%2C+Z&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </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/2411.18268">arXiv:2411.18268</a> <span> [<a href="https://arxiv.org/pdf/2411.18268">pdf</a>, <a href="https://arxiv.org/format/2411.18268">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="Information Theory">cs.IT</span> </div> </div> <p class="title is-5 mathjax"> Information geometry of bosonic Gaussian thermal states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zixin Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Wilde%2C+M+M">Mark M. Wilde</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="2411.18268v1-abstract-short" style="display: inline;"> Bosonic Gaussian thermal states form a fundamental class of states in quantum information science. This paper explores the information geometry of these states, focusing on characterizing the distance between two nearby states and the geometry induced by a parameterization in terms of their mean vectors and Hamiltonian matrices. In particular, for the family of bosonic Gaussian thermal states, we… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.18268v1-abstract-full').style.display = 'inline'; document.getElementById('2411.18268v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.18268v1-abstract-full" style="display: none;"> Bosonic Gaussian thermal states form a fundamental class of states in quantum information science. This paper explores the information geometry of these states, focusing on characterizing the distance between two nearby states and the geometry induced by a parameterization in terms of their mean vectors and Hamiltonian matrices. In particular, for the family of bosonic Gaussian thermal states, we derive expressions for their Fisher-Bures and Kubo-Mori information matrices with respect to their mean vectors and Hamiltonian matrices. An important application of our formulas consists of fundamental limits on how well one can estimate these parameters. We additionally establish formulas for the derivatives and the symmetric logarithmic derivatives of bosonic Gaussian thermal states. The former could have applications in gradient descent algorithms for quantum machine learning when using bosonic Gaussian thermal states as an ansatz, and the latter in formulating optimal strategies for single parameter estimation of bosonic Gaussian thermal states. Finally, the expressions for the aforementioned information matrices could have additional applications in natural gradient descent algorithms when using bosonic Gaussian thermal states as an ansatz. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.18268v1-abstract-full').style.display = 'none'; document.getElementById('2411.18268v1-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> 27 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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, see related work in arXiv:2410.12935 and arXiv:2410.24058</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.16830">arXiv:2411.16830</a> <span> [<a href="https://arxiv.org/pdf/2411.16830">pdf</a>, <a href="https://arxiv.org/format/2411.16830">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</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> <p class="title is-5 mathjax"> Cavity-Quantum Electrodynamics with Moir茅 Flatband Photonic Crystals </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yu-Tong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Q">Qi-Hang Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+J">Jun-Yong Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Qiao%2C+Y">Yufei Qiao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+C">Chen Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+X">Xiao-Tian Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chen-Hui Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zi-Jian Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+C">Cheng-Nian Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Meng%2C+Y">Yun Meng</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+K">Kai Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Zhan%2C+W">Wen-Kang Zhan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+C">Chao Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiaolong Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Tee%2C+C+A+T+H">Clarence Augustine T H Tee</a>, <a href="/search/quant-ph?searchtype=author&query=Sha%2C+W+E+I">Wei E. I. Sha</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhixiang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Huiyun Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+C">Chao-Yuan Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+L">Lei Ying</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Feng Liu</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="2411.16830v1-abstract-short" style="display: inline;"> Quantum emitters are a key component in photonic quantum technologies. Enhancing their single-photon emission by engineering the photonic environment using cavities can significantly improve the overall efficiency in quantum information processing. However, this enhancement is often constrained by the need for precise nanoscale control over the emitter's position within micro- or nano-cavities. In… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.16830v1-abstract-full').style.display = 'inline'; document.getElementById('2411.16830v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.16830v1-abstract-full" style="display: none;"> Quantum emitters are a key component in photonic quantum technologies. Enhancing their single-photon emission by engineering the photonic environment using cavities can significantly improve the overall efficiency in quantum information processing. However, this enhancement is often constrained by the need for precise nanoscale control over the emitter's position within micro- or nano-cavities. Inspired by the fascinating physics of moir茅 patterns, we present an approach to strongly modify the spontaneous emission rate of a quantum emitter using a finely designed multilayer moir茅 photonic crystal with a robust isolated-flatband dispersion. Theoretical analysis reveals that, due to its nearly infinite photonic density of states, the moir茅 cavity can simultaneously achieve a high Purcell factor and exhibit large tolerance over the emitter's position. We experimentally demonstrate the coupling between this moir茅 cavity and a quantum dot through the cavity-determined polarization of the dot's emission. The radiative lifetime of the quantum dot can be tuned by a factor of 40, ranging from 42 ps to 1692 ps, which is attributed to strong Purcell enhancement and Purcell inhibition effects. Our findings pave the way for moir茅 flatband cavity-enhanced quantum light sources, quantum optical switches, and quantum nodes for quantum internet applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.16830v1-abstract-full').style.display = 'none'; document.getElementById('2411.16830v1-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> 25 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.08741">arXiv:2411.08741</a> <span> [<a href="https://arxiv.org/pdf/2411.08741">pdf</a>, <a href="https://arxiv.org/ps/2411.08741">ps</a>, <a href="https://arxiv.org/format/2411.08741">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="Mathematical Physics">math-ph</span> </div> </div> <p class="title is-5 mathjax"> Unified analysis of non-Markovian open quantum systems in Gaussian environment using superoperator formalism </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+L">Lin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Park%2C+G">Gunhee Park</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Y">Yuanran Zhu</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="2411.08741v1-abstract-short" style="display: inline;"> We present perturbative error bounds for the non-Markovian dynamics of observables in open quantum systems interacting with Gaussian environments, governed by general Liouville dynamics. This extends the work of [Mascherpa et al., Phys. Rev. Lett. 118, 100401, 2017], which demonstrated qualitatively tighter bounds over the standard Gr枚nwall-type analysis, where the joint system-environment evoluti… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.08741v1-abstract-full').style.display = 'inline'; document.getElementById('2411.08741v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.08741v1-abstract-full" style="display: none;"> We present perturbative error bounds for the non-Markovian dynamics of observables in open quantum systems interacting with Gaussian environments, governed by general Liouville dynamics. This extends the work of [Mascherpa et al., Phys. Rev. Lett. 118, 100401, 2017], which demonstrated qualitatively tighter bounds over the standard Gr枚nwall-type analysis, where the joint system-environment evolution is unitary. Our results apply to systems with both bosonic and fermionic environments. Our approach utilizes a superoperator formalism, which avoids the need for formal coherent state path integral calculations, or the dilation of Lindblad dynamics into an equivalent unitary framework with infinitely many degrees of freedom. This enables a unified treatment of a wide range of open quantum systems. These findings provide a solid theoretical basis for various recently developed pseudomode methods in simulating open quantum system dynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.08741v1-abstract-full').style.display = 'none'; document.getElementById('2411.08741v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">46 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.07615">arXiv:2411.07615</a> <span> [<a href="https://arxiv.org/pdf/2411.07615">pdf</a>, <a href="https://arxiv.org/format/2411.07615">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Real-time propagation of adaptive sampling selected configuration interaction wave function </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Shee%2C+A">Avijit Shee</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Head-Gordon%2C+M">Martin Head-Gordon</a>, <a href="/search/quant-ph?searchtype=author&query=Whaley%2C+K+B">K. Birgitta Whaley</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="2411.07615v1-abstract-short" style="display: inline;"> We have developed a new time propagation method, time-dependent adaptive sampling configuration interaction (TD-ASCI), to describe the dynamics of a strongly correlated system. We employ the short iterative Lanczos (SIL) method as the time-integrator, which provides a unitary, norm-conserving, and stable long-time propagation scheme. We used the TD-ASCI method to evaluate the time-domain correlati… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.07615v1-abstract-full').style.display = 'inline'; document.getElementById('2411.07615v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.07615v1-abstract-full" style="display: none;"> We have developed a new time propagation method, time-dependent adaptive sampling configuration interaction (TD-ASCI), to describe the dynamics of a strongly correlated system. We employ the short iterative Lanczos (SIL) method as the time-integrator, which provides a unitary, norm-conserving, and stable long-time propagation scheme. We used the TD-ASCI method to evaluate the time-domain correlation functions of molecular systems. The accuracy of the correlation function was assessed by Fourier transforming (FT) into the frequency domain to compute the dipole-allowed absorption spectra. The FT has been carried out with a short-time signal of the correlation function to reduce the computation time, using an efficient alternative FT scheme based on the ESPRIT signal processing algorithm. We have applied the {TD-ASCI} method to prototypical strongly correlated molecular systems and compared the absorption spectra to spectra evaluated using the equation of motion coupled cluster (EOMCC) method with a truncation at single-doubles-triples (SDT) level. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.07615v1-abstract-full').style.display = 'none'; document.getElementById('2411.07615v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.10432">arXiv:2410.10432</a> <span> [<a href="https://arxiv.org/pdf/2410.10432">pdf</a>, <a href="https://arxiv.org/format/2410.10432">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"> Individual solid-state nuclear spin qubits with coherence exceeding seconds </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=O%27Sullivan%2C+J">James O'Sullivan</a>, <a href="/search/quant-ph?searchtype=author&query=Travesedo%2C+J">Jaime Travesedo</a>, <a href="/search/quant-ph?searchtype=author&query=Pallegoix%2C+L">Louis Pallegoix</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z+W">Zhiyuan W. Huang</a>, <a href="/search/quant-ph?searchtype=author&query=May%2C+A">Alexande May</a>, <a href="/search/quant-ph?searchtype=author&query=Yavkin%2C+B">Boris Yavkin</a>, <a href="/search/quant-ph?searchtype=author&query=Hogan%2C+P">Patrick Hogan</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+S">Sen Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Renbao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Chaneliere%2C+T">Thierry Chaneliere</a>, <a href="/search/quant-ph?searchtype=author&query=Bertaina%2C+S">Sylvain Bertaina</a>, <a href="/search/quant-ph?searchtype=author&query=Goldner%2C+P">Philippe Goldner</a>, <a href="/search/quant-ph?searchtype=author&query=Esteve%2C+D">Daniel Esteve</a>, <a href="/search/quant-ph?searchtype=author&query=Vion%2C+D">Denis Vion</a>, <a href="/search/quant-ph?searchtype=author&query=Abgrall%2C+P">Patrick Abgrall</a>, <a href="/search/quant-ph?searchtype=author&query=Bertet%2C+P">Patrice Bertet</a>, <a href="/search/quant-ph?searchtype=author&query=Flurin%2C+E">Emmanuel Flurin</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="2410.10432v2-abstract-short" style="display: inline;"> The ability to coherently control and read out qubits with long coherence times in a scalable system is a crucial requirement for any quantum processor. Nuclear spins in the solid state have shown great promise as long-lived qubits. Control and readout of individual nuclear spin qubit registers has made major progress in the recent years using individual electron spin ancilla addressed either elec… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.10432v2-abstract-full').style.display = 'inline'; document.getElementById('2410.10432v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.10432v2-abstract-full" style="display: none;"> The ability to coherently control and read out qubits with long coherence times in a scalable system is a crucial requirement for any quantum processor. Nuclear spins in the solid state have shown great promise as long-lived qubits. Control and readout of individual nuclear spin qubit registers has made major progress in the recent years using individual electron spin ancilla addressed either electrically or optically. Here, we present a new platform for quantum information processing, consisting of $^{183}$W nuclear spin qubits adjacent to an Er$^{3+}$ impurity in a CaWO$_4$ crystal, interfaced via a superconducting resonator and detected using a microwave photon counter at 10mK. We study two nuclear spin qubits with $T_2^*$ of $0.8(2)~$s and $1.2(3)~$s, $T_2$ of $3.4(4)~$s and $4.4(6)~$ s, respectively. We demonstrate single-shot quantum non-demolition readout of each nuclear spin qubit using the Er$^{3+}$ spin as an ancilla. We introduce a new scheme for all-microwave single- and two-qubit gates, based on stimulated Raman driving of the coupled electron-nuclear spin system. We realize single- and two-qubit gates on a timescale of a few milliseconds, and prepare a decoherence-protected Bell state with 88% fidelity and $T_2^*$ of $1.7(2)~$s. Our results are a proof-of-principle demonstrating the potential of solid-state nuclear spin qubits as a promising platform for quantum information processing. With the potential to scale to tens or hundreds of qubits, this platform has prospects for the development of scalable quantum processors with long-lived qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.10432v2-abstract-full').style.display = 'none'; document.getElementById('2410.10432v2-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> 27 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">14 pages, 4 main figures, 7 supplementary 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/2409.13258">arXiv:2409.13258</a> <span> [<a href="https://arxiv.org/pdf/2409.13258">pdf</a>, <a href="https://arxiv.org/ps/2409.13258">ps</a>, <a href="https://arxiv.org/format/2409.13258">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Hybrid-Order Topological Phase And Transition in 1H Transition Metal Compounds </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yang%2C+N">Ning-Jing Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhigao Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jian-Min Zhang</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="2409.13258v1-abstract-short" style="display: inline;"> Inspired by recent experimental observations of hybrid topological states [Nature 628, 527 (2024)], we predict hybrid-order topological insulators (HOTIs) in 1H transition metal compounds (TMCs), where both second-order and first-order topological states coexist near the Fermi level. Initially, 1H-TMCs exhibit a second-order topological phase due to the d-orbital band gap. Upon coupling of p- and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.13258v1-abstract-full').style.display = 'inline'; document.getElementById('2409.13258v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.13258v1-abstract-full" style="display: none;"> Inspired by recent experimental observations of hybrid topological states [Nature 628, 527 (2024)], we predict hybrid-order topological insulators (HOTIs) in 1H transition metal compounds (TMCs), where both second-order and first-order topological states coexist near the Fermi level. Initially, 1H-TMCs exhibit a second-order topological phase due to the d-orbital band gap. Upon coupling of p- and d- orbitals couple, first-order topological characteristics emerge. This hybrid-order topological phase transition is tunable via crystal field effects. Combined with first-principles calculations, we illustrate the phase transition with WTe2 and NbSe2. In addition, the first-order topological band gap of the HOTI exhibits a strong spin Hall effect. Our finding reveal novel hybrid-order topological phase in 2D electron materials and highlight spintronic applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.13258v1-abstract-full').style.display = 'none'; document.getElementById('2409.13258v1-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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 gages, 4 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/2408.15529">arXiv:2408.15529</a> <span> [<a href="https://arxiv.org/pdf/2408.15529">pdf</a>, <a href="https://arxiv.org/format/2408.15529">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="Chemical Physics">physics.chem-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-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/PhysRevB.110.195148">10.1103/PhysRevB.110.195148 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quasi-Lindblad pseudomode theory for open quantum systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Park%2C+G">Gunhee Park</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Y">Yuanran Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+C">Chao Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Chan%2C+G+K">Garnet Kin-Lic Chan</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+L">Lin Lin</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="2408.15529v2-abstract-short" style="display: inline;"> We introduce a new framework to study the dynamics of open quantum systems with linearly coupled Gaussian baths. Our approach replaces the continuous bath with an auxiliary discrete set of pseudomodes with dissipative dynamics, but we further relax the complete positivity requirement in the Lindblad master equation and formulate a quasi-Lindblad pseudomode theory. We show that this quasi-Lindblad… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.15529v2-abstract-full').style.display = 'inline'; document.getElementById('2408.15529v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.15529v2-abstract-full" style="display: none;"> We introduce a new framework to study the dynamics of open quantum systems with linearly coupled Gaussian baths. Our approach replaces the continuous bath with an auxiliary discrete set of pseudomodes with dissipative dynamics, but we further relax the complete positivity requirement in the Lindblad master equation and formulate a quasi-Lindblad pseudomode theory. We show that this quasi-Lindblad pseudomode formulation directly leads to a representation of the bath correlation function in terms of a complex weighted sum of complex exponentials, an expansion that is known to be rapidly convergent in practice and thus leads to a compact set of pseudomodes. The pseudomode representation is not unique and can differ by a gauge choice. When the global dynamics can be simulated exactly, the system dynamics is unique and independent of the specific pseudomode representation. However, the gauge choice may affect the stability of the global dynamics, and we provide an analysis of why and when the global dynamics can retain stability despite losing positivity. We showcase the performance of this formulation across various spectral densities in both bosonic and fermionic problems, finding significant improvements over conventional pseudomode formulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.15529v2-abstract-full').style.display = 'none'; document.getElementById('2408.15529v2-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> 25 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 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">13 pages, 6 figures (main text); 8 pages, 1 figure (Supplementary Material)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review B 110, 195148 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.14282">arXiv:2408.14282</a> <span> [<a href="https://arxiv.org/pdf/2408.14282">pdf</a>, <a href="https://arxiv.org/format/2408.14282">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> </div> </div> <p class="title is-5 mathjax"> All-microwave spectroscopy and polarization of individual nuclear spins in a solid </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Travesedo%2C+J">J. Travesedo</a>, <a href="/search/quant-ph?searchtype=author&query=O%27Sullivan%2C+J">J. O'Sullivan</a>, <a href="/search/quant-ph?searchtype=author&query=Pallegoix%2C+L">L. Pallegoix</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z+W">Z. W. Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Hogan%2C+P">P. Hogan</a>, <a href="/search/quant-ph?searchtype=author&query=Goldner%2C+P">P. Goldner</a>, <a href="/search/quant-ph?searchtype=author&query=Chaneliere%2C+T">T. Chaneliere</a>, <a href="/search/quant-ph?searchtype=author&query=Bertaina%2C+S">S. Bertaina</a>, <a href="/search/quant-ph?searchtype=author&query=Esteve%2C+D">D. Esteve</a>, <a href="/search/quant-ph?searchtype=author&query=Abgrall%2C+P">P. Abgrall</a>, <a href="/search/quant-ph?searchtype=author&query=Vion%2C+D">D. Vion</a>, <a href="/search/quant-ph?searchtype=author&query=Flurin%2C+E">E. Flurin</a>, <a href="/search/quant-ph?searchtype=author&query=Bertet%2C+P">P. Bertet</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="2408.14282v2-abstract-short" style="display: inline;"> We report magnetic resonance spectroscopy measurements of individual nuclear spins in a crystal coupled to a neighbouring paramagnetic center, detected using microwave fluorescence at millikelvin temperatures. We observe real-time quantum jumps of the nuclear spin state, a proof of their individual nature. By driving the forbidden transitions of the coupled electron-nuclear spin system, we also ac… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14282v2-abstract-full').style.display = 'inline'; document.getElementById('2408.14282v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.14282v2-abstract-full" style="display: none;"> We report magnetic resonance spectroscopy measurements of individual nuclear spins in a crystal coupled to a neighbouring paramagnetic center, detected using microwave fluorescence at millikelvin temperatures. We observe real-time quantum jumps of the nuclear spin state, a proof of their individual nature. By driving the forbidden transitions of the coupled electron-nuclear spin system, we also achieve single-spin solid-effect dynamical nuclear polarization. Relying exclusively on microwave driving and microwave photon counting, the methods reported here are in principle applicable to a large number of electron-nuclear spin systems, in a wide variety of samples. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14282v2-abstract-full').style.display = 'none'; document.getElementById('2408.14282v2-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> 16 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 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/2407.08297">arXiv:2407.08297</a> <span> [<a href="https://arxiv.org/pdf/2407.08297">pdf</a>, <a href="https://arxiv.org/format/2407.08297">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"> The trade-off between diagonal and off-diagonal elements in the eigenstate thermalization hypothesis </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhiqiang Huang</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="2407.08297v2-abstract-short" style="display: inline;"> To bypass using local observables as intermediate quantities in proving the eigenstate thermalization hypothesis (ETH), we have introduced an observable-independent measure of distinguishability. In this paper, we establish the connection between this measure and several other ETH measures in a more natural way. We first demonstrate a universal trade-off relation between the diagonal and off-diago… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.08297v2-abstract-full').style.display = 'inline'; document.getElementById('2407.08297v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.08297v2-abstract-full" style="display: none;"> To bypass using local observables as intermediate quantities in proving the eigenstate thermalization hypothesis (ETH), we have introduced an observable-independent measure of distinguishability. In this paper, we establish the connection between this measure and several other ETH measures in a more natural way. We first demonstrate a universal trade-off relation between the diagonal and off-diagonal elements of the measure. We then extend this discussion to eigenstate typicality and the average observable. This trade-off relationship reveals that the exponential growth of off-diagonal elements directly suppresses their own values, as well as indirectly suppressing the diagonal elements. This provides a new perspective on the physical mechanisms underlying ETH. Finally, through numerical calculations on a one-dimensional Ising spin chain, we explore various trade-off relationships and examine strong and weak ETH. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.08297v2-abstract-full').style.display = 'none'; document.getElementById('2407.08297v2-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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, 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/2406.19060">arXiv:2406.19060</a> <span> [<a href="https://arxiv.org/pdf/2406.19060">pdf</a>, <a href="https://arxiv.org/format/2406.19060">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="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mathematical Physics">math-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optimization and Control">math.OC</span> </div> </div> <p class="title is-5 mathjax"> Semi-definite optimization of the measured relative entropies of quantum states and channels </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zixin Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Wilde%2C+M+M">Mark M. Wilde</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="2406.19060v1-abstract-short" style="display: inline;"> The measured relative entropies of quantum states and channels find operational significance in quantum information theory as achievable error rates in hypothesis testing tasks. They are of interest in the near term, as they correspond to hybrid quantum-classical strategies with technological requirements far less challenging to implement than required by the most general strategies allowed by qua… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.19060v1-abstract-full').style.display = 'inline'; document.getElementById('2406.19060v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.19060v1-abstract-full" style="display: none;"> The measured relative entropies of quantum states and channels find operational significance in quantum information theory as achievable error rates in hypothesis testing tasks. They are of interest in the near term, as they correspond to hybrid quantum-classical strategies with technological requirements far less challenging to implement than required by the most general strategies allowed by quantum mechanics. In this paper, we prove that these measured relative entropies can be calculated efficiently by means of semi-definite programming, by making use of variational formulas for the measured relative entropies of states and semi-definite representations of the weighted geometric mean and the operator connection of the logarithm. Not only do the semi-definite programs output the optimal values of the measured relative entropies of states and channels, but they also provide numerical characterizations of optimal strategies for achieving them, which is of significant practical interest for designing hypothesis testing protocols. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.19060v1-abstract-full').style.display = 'none'; document.getElementById('2406.19060v1-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> 27 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">33 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.09345">arXiv:2403.09345</a> <span> [<a href="https://arxiv.org/pdf/2403.09345">pdf</a>, <a href="https://arxiv.org/format/2403.09345">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mathematical Physics">math-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Analysis of PDEs">math.AP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Classical-Quantum correspondence in Lindblad evolution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Galkowski%2C+J">Jeffrey Galkowski</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zworski%2C+M">Maciej Zworski</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="2403.09345v4-abstract-short" style="display: inline;"> We show that for the Lindblad evolution defined using (at most) quadratically growing classical Hamiltonians and (at most) linearly growing classical jump functions (quantized into jump operators assumed to satisfy certain ellipticity conditions and modeling interaction with a larger system), the evolution of a quantum observable remains close to the classical Fokker--Planck evolution in the Hilbe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.09345v4-abstract-full').style.display = 'inline'; document.getElementById('2403.09345v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.09345v4-abstract-full" style="display: none;"> We show that for the Lindblad evolution defined using (at most) quadratically growing classical Hamiltonians and (at most) linearly growing classical jump functions (quantized into jump operators assumed to satisfy certain ellipticity conditions and modeling interaction with a larger system), the evolution of a quantum observable remains close to the classical Fokker--Planck evolution in the Hilbert--Schmidt norm for times vastly exceeding the Ehrenfest time (the limit of such agreement with no jump operators). The time scale is the same as in the recent papers by Hern谩ndez--Ranard--Riedel but the statement and methods are different. The appendix presents numerical experiments illustrating the classical/quantum correspondence in Lindblad evolution and comparing it to the mathematical results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.09345v4-abstract-full').style.display = 'none'; document.getElementById('2403.09345v4-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> 19 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">Main article by Jeffrey Galkowski and Maciej Zworski with an appendix by Zhen Huang and Maciej Zworski -- new appendix with numerical experiments and a new section providing estimates for the Hilbert--Schmidt norm under Lindblad evolution</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.04240">arXiv:2403.04240</a> <span> [<a href="https://arxiv.org/pdf/2403.04240">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> </div> </div> <p class="title is-5 mathjax"> Image enhancement algorithm for absorption imaging </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+P">Pengcheng Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Songqian Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Z">Zhu Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+H">Haipo Niu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+J">Jiatao Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zerui Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+C">Chengyin Han</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+B">Bo Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+P">Peiliang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+C">Chaohong Lee</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="2403.04240v1-abstract-short" style="display: inline;"> The noise in absorption imaging of cold atoms significantly impacts measurement accuracy across a range of applications with ultracold atoms. It is crucial to adopt an approach that offers effective denoising capabilities without compromising the unique structure of the atoms. Here we introduce a novel image enhancement algorithm for cold atomic absorption imaging. The algorithm successfully suppr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.04240v1-abstract-full').style.display = 'inline'; document.getElementById('2403.04240v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.04240v1-abstract-full" style="display: none;"> The noise in absorption imaging of cold atoms significantly impacts measurement accuracy across a range of applications with ultracold atoms. It is crucial to adopt an approach that offers effective denoising capabilities without compromising the unique structure of the atoms. Here we introduce a novel image enhancement algorithm for cold atomic absorption imaging. The algorithm successfully suppresses background noise, enhancing image contrast significantly. Experimental results showcase that this approach can enhance the accuracy of cold atom particle number measurements by approximately tenfold, all while preserving essential information. Moreover, the method exhibits exceptional performance and robustness when confronted with fringe noise and multi-component imaging scenarios, offering high stability. Importantly, the optimization process is entirely automated, eliminating the need for manual parameter selection. The method is both compatible and practical, making it applicable across various absorption imaging fields. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.04240v1-abstract-full').style.display = 'none'; document.getElementById('2403.04240v1-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 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.05793">arXiv:2402.05793</a> <span> [<a href="https://arxiv.org/pdf/2402.05793">pdf</a>, <a href="https://arxiv.org/format/2402.05793">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="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.5.020354">10.1103/PRXQuantum.5.020354 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exact quantum sensing limits for bosonic dephasing channels </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zixin Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Lami%2C+L">Ludovico Lami</a>, <a href="/search/quant-ph?searchtype=author&query=Wilde%2C+M+M">Mark M. Wilde</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="2402.05793v1-abstract-short" style="display: inline;"> Dephasing is a prominent noise mechanism that afflicts quantum information carriers, and it is one of the main challenges towards realizing useful quantum computation, communication, and sensing. Here we consider discrimination and estimation of bosonic dephasing channels, when using the most general adaptive strategies allowed by quantum mechanics. We reduce these difficult quantum problems to si… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.05793v1-abstract-full').style.display = 'inline'; document.getElementById('2402.05793v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.05793v1-abstract-full" style="display: none;"> Dephasing is a prominent noise mechanism that afflicts quantum information carriers, and it is one of the main challenges towards realizing useful quantum computation, communication, and sensing. Here we consider discrimination and estimation of bosonic dephasing channels, when using the most general adaptive strategies allowed by quantum mechanics. We reduce these difficult quantum problems to simple classical ones based on the probability densities defining the bosonic dephasing channels. By doing so, we rigorously establish the optimal performance of various distinguishability and estimation tasks and construct explicit strategies to achieve this performance. To the best of our knowledge, this is the first example of a non-Gaussian bosonic channel for which there are exact solutions for these tasks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.05793v1-abstract-full').style.display = 'none'; document.getElementById('2402.05793v1-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 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">v1: 21 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum, vol. 5, no. 2, page 020354, June 2024 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.15871">arXiv:2401.15871</a> <span> [<a href="https://arxiv.org/pdf/2401.15871">pdf</a>, <a href="https://arxiv.org/format/2401.15871">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"> Enhancing the expressivity of quantum neural networks with residual connections </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wen%2C+J">Jingwei Wen</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhiguo Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+D">Dunbo Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+L">Ling Qian</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="2401.15871v1-abstract-short" style="display: inline;"> In the recent noisy intermediate-scale quantum era, the research on the combination of artificial intelligence and quantum computing has been greatly developed. Inspired by neural networks, developing quantum neural networks with specific structures is one of the most promising directions for improving network performance. In this work, we propose a quantum circuit-based algorithm to implement qua… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.15871v1-abstract-full').style.display = 'inline'; document.getElementById('2401.15871v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.15871v1-abstract-full" style="display: none;"> In the recent noisy intermediate-scale quantum era, the research on the combination of artificial intelligence and quantum computing has been greatly developed. Inspired by neural networks, developing quantum neural networks with specific structures is one of the most promising directions for improving network performance. In this work, we propose a quantum circuit-based algorithm to implement quantum residual neural networks (QResNets), where the residual connection channels are constructed by introducing auxiliary qubits to the data-encoding and trainable blocks of the quantum neural networks. Importantly, we prove that when this particular network architecture is applied to a $l$-layer data-encoding, the number of frequency generation forms can be extended from one, namely the difference of the sum of generator eigenvalues, to $\mathcal{O}(l^2)$. And the flexibility in adjusting the corresponding Fourier coefficients can also be improved due to the diversity of spectrum construction methods and the additional optimization degrees of freedom in the generalized residual operators. These results indicate that the residual encoding scheme can achieve better spectral richness and enhance the expressivity of various parameterized quantum circuits. Extensive numerical demonstrations in regression tasks of fitting various functions and applications in image classification with MNIST datasets are offered to present the expressivity enhancement. Our work lays the foundation for a complete quantum implementation of the classical residual neural networks and explores a new strategy for quantum feature map in quantum machine learning. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.15871v1-abstract-full').style.display = 'none'; document.getElementById('2401.15871v1-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.10993">arXiv:2401.10993</a> <span> [<a href="https://arxiv.org/pdf/2401.10993">pdf</a>, <a href="https://arxiv.org/format/2401.10993">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> <p class="title is-5 mathjax"> Mixed state topological order parameters for symmetry protected fermion matter </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ze-Min Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Diehl%2C+S">Sebastian Diehl</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="2401.10993v1-abstract-short" style="display: inline;"> We construct an observable mixed state topological order parameter for symmetry-protected free fermion matter. It resolves the entire table of topological insulators and superconductors, relying exclusively on the symmetry class, but not on unitary symmetries. It provides a robust, quantized signal not only for pure ground states, but also for mixed states in- or out of thermal equilibrium. Key in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.10993v1-abstract-full').style.display = 'inline'; document.getElementById('2401.10993v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.10993v1-abstract-full" style="display: none;"> We construct an observable mixed state topological order parameter for symmetry-protected free fermion matter. It resolves the entire table of topological insulators and superconductors, relying exclusively on the symmetry class, but not on unitary symmetries. It provides a robust, quantized signal not only for pure ground states, but also for mixed states in- or out of thermal equilibrium. Key ingredient is a unitary probe operator, whose phase can be related to spectral asymmetry, in turn revealing the topological properties of the underlying state. This is demonstrated analytically in the continuum limit, and validated numerically on the lattice. The order parameter is experimentally accessible via either interferometry or full counting statistics, for example, in cold atom experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.10993v1-abstract-full').style.display = 'none'; document.getElementById('2401.10993v1-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> 19 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">7+15 pages, 7 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/2401.08325">arXiv:2401.08325</a> <span> [<a href="https://arxiv.org/pdf/2401.08325">pdf</a>, <a href="https://arxiv.org/format/2401.08325">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/10.1364/OE.515390">10.1364/OE.515390 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum Random Number Generation Based on Phase Reconstruction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Jialiang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zitao Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+C">Chunlin Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+J">Jiajie Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+T">Tongge Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+X">Xiangwei Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+S">Shihai Sun</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="2401.08325v1-abstract-short" style="display: inline;"> Quantum random number generator (QRNG) utilizes the intrinsic randomness of quantum systems to generate completely unpredictable and genuine random numbers, finding wide applications across many fields. QRNGs relying on the phase noise of a laser have attracted considerable attention due to their straightforward system architecture and high random number generation rates. However, traditional phas… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.08325v1-abstract-full').style.display = 'inline'; document.getElementById('2401.08325v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.08325v1-abstract-full" style="display: none;"> Quantum random number generator (QRNG) utilizes the intrinsic randomness of quantum systems to generate completely unpredictable and genuine random numbers, finding wide applications across many fields. QRNGs relying on the phase noise of a laser have attracted considerable attention due to their straightforward system architecture and high random number generation rates. However, traditional phase noise QRNGs suffer from a 50\% loss of quantum entropy during the randomness extraction process. In this paper, we propose a phase-reconstruction quantum random number generation scheme, in which the phase noise of a laser is reconstructed by simultaneously measuring the orthogonal quadratures of the light field using balanced detectors. This enables direct discretization of uniform phase noise, and the min-entropy can achieve a value of 1. Furthermore, our approach exhibits inherent robustness against the classical phase fluctuations of the unbalanced interferometer, eliminating the need for active compensation. Finally, we conducted experimental validation using commercial optical hybrid and balanced detectors, achieving a random number generation rate of 1.96 Gbps at a sampling rate of 200 MSa/s. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.08325v1-abstract-full').style.display = 'none'; document.getElementById('2401.08325v1-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> 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">Comments:</span> <span class="has-text-grey-dark mathjax">11pages. Submitted to Optics Express, and any comment is welcome</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Optics Express,Vol.32,No.4, 2024 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.06664">arXiv:2312.06664</a> <span> [<a href="https://arxiv.org/pdf/2312.06664">pdf</a>, <a href="https://arxiv.org/format/2312.06664">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> </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.L042014">10.1103/PhysRevResearch.6.L042014 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Accurate optimal quantum error correction thresholds from coherent information </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Colmenarez%2C+L">Luis Colmenarez</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ze-Min Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Diehl%2C+S">Sebastian Diehl</a>, <a href="/search/quant-ph?searchtype=author&query=M%C3%BCller%2C+M">Markus M眉ller</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="2312.06664v2-abstract-short" style="display: inline;"> Quantum error correcting (QEC) codes protect quantum information from decoherence, as long as error rates fall below critical error thresholds. In general, obtaining thresholds implies simulating the QEC procedure using, in general, sub-optimal decoding strategies. In a few cases and for sufficiently simple noise models, optimal decoding of QEC codes can be framed as a phase transition in disorder… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.06664v2-abstract-full').style.display = 'inline'; document.getElementById('2312.06664v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.06664v2-abstract-full" style="display: none;"> Quantum error correcting (QEC) codes protect quantum information from decoherence, as long as error rates fall below critical error thresholds. In general, obtaining thresholds implies simulating the QEC procedure using, in general, sub-optimal decoding strategies. In a few cases and for sufficiently simple noise models, optimal decoding of QEC codes can be framed as a phase transition in disordered classical spin models. In both situations, accurate estimation of thresholds demands intensive computational resources. Here we use the coherent information of the mixed state of noisy QEC codes to accurately estimate the associated optimal QEC thresholds already from small-distance codes at moderate computational cost. We show the effectiveness and versatility of our method by applying it first to the topological surface and color code under bit-flip and depolarizing noise. We then extend the coherent information based methodology to phenomenological and quantum circuit level noise settings. For all examples considered we obtain highly accurate estimates of optimal error thresholds from small, low-distance instances of the codes, in close accordance with threshold values reported in the literature. Our findings establish the coherent information as a reliable competitive practical tool for the calculation of optimal thresholds of state-of-the-art QEC codes under realistic noise models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.06664v2-abstract-full').style.display = 'none'; document.getElementById('2312.06664v2-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">9 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/2312.00410">arXiv:2312.00410</a> <span> [<a href="https://arxiv.org/pdf/2312.00410">pdf</a>, <a href="https://arxiv.org/ps/2312.00410">ps</a>, <a href="https://arxiv.org/format/2312.00410">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/PhysRevE.109.054120">10.1103/PhysRevE.109.054120 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Subsystem eigenstate thermalization hypothesis for translation invariant systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhiqiang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+X">Xiao-Kan Guo</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="2312.00410v4-abstract-short" style="display: inline;"> The eigenstate thermalization hypothesis for translation invariant quantum spin systems has been proved recently by using random matrices. In this paper, we study the subsystem version of eigenstate thermalization hypothesis for translation invariant quantum systems without referring to random matrices. We first find a relation between the quantum variance and the Belavkin-Staszewski relative entr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.00410v4-abstract-full').style.display = 'inline'; document.getElementById('2312.00410v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.00410v4-abstract-full" style="display: none;"> The eigenstate thermalization hypothesis for translation invariant quantum spin systems has been proved recently by using random matrices. In this paper, we study the subsystem version of eigenstate thermalization hypothesis for translation invariant quantum systems without referring to random matrices. We first find a relation between the quantum variance and the Belavkin-Staszewski relative entropy. Then, by showing the small upper bounds on the quantum variance and the Belavkin-Staszewski relative entropy, we prove the subsystem eigenstate thermalization hypothesis for translation invariant quantum systems with an algebraic speed of convergence in an elementary way. The proof holds for most of the translation invariant quantum lattice models with exponential or algebraic decays of correlations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.00410v4-abstract-full').style.display = 'none'; document.getElementById('2312.00410v4-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">9 pages</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. E 109, 054120 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.05159">arXiv:2311.05159</a> <span> [<a href="https://arxiv.org/pdf/2311.05159">pdf</a>, <a href="https://arxiv.org/format/2311.05159">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/PhysRevA.109.052434">10.1103/PhysRevA.109.052434 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Limited quantum advantage for stellar interferometry via continuous-variable teleportation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zixin Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Baragiola%2C+B+Q">Ben Q. Baragiola</a>, <a href="/search/quant-ph?searchtype=author&query=Menicucci%2C+N+C">Nicolas C. Menicucci</a>, <a href="/search/quant-ph?searchtype=author&query=Wilde%2C+M+M">Mark M. Wilde</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="2311.05159v3-abstract-short" style="display: inline;"> We consider stellar interferometry in the continuous-variable (CV) quantum information formalism and use the quantum Fisher information (QFI) to characterize the performance of three key strategies: direct interferometry (DI), local heterodyne measurement, and a CV teleportation-based strategy. In the lossless regime, we show that a squeezing parameter of $r\approx 2$ (18 dB) is required to reach… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.05159v3-abstract-full').style.display = 'inline'; document.getElementById('2311.05159v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.05159v3-abstract-full" style="display: none;"> We consider stellar interferometry in the continuous-variable (CV) quantum information formalism and use the quantum Fisher information (QFI) to characterize the performance of three key strategies: direct interferometry (DI), local heterodyne measurement, and a CV teleportation-based strategy. In the lossless regime, we show that a squeezing parameter of $r\approx 2$ (18 dB) is required to reach $\approx$ 95\% of the QFI achievable with DI; such a squeezing level is beyond what has been achieved experimentally. In the low-loss regime, the CV teleportation strategy becomes inferior to DI, and the performance gap widens as loss increases. Curiously, in the high-loss regime, a small region of loss exists where the CV teleportation strategy slightly outperforms both DI and local heterodyne, representing a transition in the optimal strategy. We describe this advantage as limited because it occurs for a small region of loss, and the magnitude of the advantage is also small. We argue that practical difficulties further impede achieving any quantum advantage, limiting the merits of a CV teleportation-based strategy for stellar interferometry. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.05159v3-abstract-full').style.display = 'none'; document.getElementById('2311.05159v3-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> 18 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 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">18 pages, 6 figures, codes included. Comments are welcome</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review A, Vol. 109, No. 5, page 052434, May 2024 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.01332">arXiv:2311.01332</a> <span> [<a href="https://arxiv.org/pdf/2311.01332">pdf</a>, <a href="https://arxiv.org/format/2311.01332">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/PhysRevApplied.22.034007">10.1103/PhysRevApplied.22.034007 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fast ZZ-Free Entangling Gates for Superconducting Qubits Assisted by a Driven Resonator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ziwen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+T">Taeyoon Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Roy%2C+T">Tanay Roy</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Y">Yao Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Romanenko%2C+A">Alexander Romanenko</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+S">Shaojiang Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Grassellino%2C+A">Anna Grassellino</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="2311.01332v1-abstract-short" style="display: inline;"> Engineering high-fidelity two-qubit gates is an indispensable step toward practical quantum computing. For superconducting quantum platforms, one important setback is the stray interaction between qubits, which causes significant coherent errors. For transmon qubits, protocols for mitigating such errors usually involve fine-tuning the hardware parameters or introducing usually noisy flux-tunable c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.01332v1-abstract-full').style.display = 'inline'; document.getElementById('2311.01332v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.01332v1-abstract-full" style="display: none;"> Engineering high-fidelity two-qubit gates is an indispensable step toward practical quantum computing. For superconducting quantum platforms, one important setback is the stray interaction between qubits, which causes significant coherent errors. For transmon qubits, protocols for mitigating such errors usually involve fine-tuning the hardware parameters or introducing usually noisy flux-tunable couplers. In this work, we propose a simple scheme to cancel these stray interactions. The coupler used for such cancellation is a driven high-coherence resonator, where the amplitude and frequency of the drive serve as control knobs. Through the resonator-induced-phase (RIP) interaction, the static ZZ coupling can be entirely neutralized. We numerically show that such a scheme can enable short and high-fidelity entangling gates, including cross-resonance CNOT gates within 40 ns and adiabatic CZ gates within 140 ns. Our architecture is not only ZZ free but also contains no extra noisy components, such that it preserves the coherence times of fixed-frequency transmon qubits. With the state-of-the-art coherence times, the error of our cross-resonance CNOT gate can be reduced to below 1e-4. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.01332v1-abstract-full').style.display = 'none'; document.getElementById('2311.01332v1-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, 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">Report number:</span> FERMILAB-PUB-23-549-SQMS </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 22, 034007 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.01083">arXiv:2310.01083</a> <span> [<a href="https://arxiv.org/pdf/2310.01083">pdf</a>, <a href="https://arxiv.org/format/2310.01083">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"> Error filtration for quantum sensing via interferometry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zixin Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Lupo%2C+C">Cosmo Lupo</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="2310.01083v3-abstract-short" style="display: inline;"> Dephasing is a main noise mechanism that afflicts quantum information, it reduces visibility, and destroys coherence and entanglement. Therefore, it must be reduced, mitigated, and if possible corrected, to allow for demonstration of quantum advantage in any application of quantum technology, from computing to sensing and communications. Here we discuss a hardware scheme of error filtration to mit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.01083v3-abstract-full').style.display = 'inline'; document.getElementById('2310.01083v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.01083v3-abstract-full" style="display: none;"> Dephasing is a main noise mechanism that afflicts quantum information, it reduces visibility, and destroys coherence and entanglement. Therefore, it must be reduced, mitigated, and if possible corrected, to allow for demonstration of quantum advantage in any application of quantum technology, from computing to sensing and communications. Here we discuss a hardware scheme of error filtration to mitigate the effects of dephasing in optical quantum metrology. The scheme uses only passive linear optics and ancillary vacuum modes, without need of single-photon sources or entanglement. It exploits constructive and destructive interference to partially cancel the detrimental effects of statistically independent sources of dephasing. We apply this scheme to preserve coherent states and to phase-stabilize stellar interferometry, showing that a significant improvement can be obtained by using only a few ancillary modes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.01083v3-abstract-full').style.display = 'none'; document.getElementById('2310.01083v3-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> 16 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 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">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 11 figures, comments are welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.08890">arXiv:2309.08890</a> <span> [<a href="https://arxiv.org/pdf/2309.08890">pdf</a>, <a href="https://arxiv.org/ps/2309.08890">ps</a>, <a href="https://arxiv.org/format/2309.08890">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/10.1021/acs.jctc.3c01099">10.1021/acs.jctc.3c01099 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Stochastic Schr枚dinger equation approach to real-time dynamics of Anderson-Holstein impurities: an open quantum system perspective </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+L">Limin Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Z">Zhennan Zhou</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="2309.08890v1-abstract-short" style="display: inline;"> We develop a stochastic Schr枚dinger equation (SSE) framework to simulate real-time dynamics of Anderson-Holstein (AH) impurities coupled to a continuous fermionic bath. The bath degrees of freedom are incorporated through fluctuating terms determined by exact system-bath correlations, which is derived in an ab initio manner. We show that such an SSE treatment provides a middle ground between numer… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.08890v1-abstract-full').style.display = 'inline'; document.getElementById('2309.08890v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.08890v1-abstract-full" style="display: none;"> We develop a stochastic Schr枚dinger equation (SSE) framework to simulate real-time dynamics of Anderson-Holstein (AH) impurities coupled to a continuous fermionic bath. The bath degrees of freedom are incorporated through fluctuating terms determined by exact system-bath correlations, which is derived in an ab initio manner. We show that such an SSE treatment provides a middle ground between numerically expansive microscopic simulations and macroscopic master equations. Computationally, the SSE model enables efficient numerical methods for propagating stochastic trajectories. We demonstrate that this approach not only naturally provides microscopically-detailed information unavailable from reduced models, but also captures effects beyond master equations, thus serves as a promising tool to study open quantum dynamics emerging in physics and chemistry. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.08890v1-abstract-full').style.display = 'none'; document.getElementById('2309.08890v1-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> 16 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">16 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/2309.05720">arXiv:2309.05720</a> <span> [<a href="https://arxiv.org/pdf/2309.05720">pdf</a>, <a href="https://arxiv.org/format/2309.05720">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> </div> </div> <p class="title is-5 mathjax"> Tunable inductive coupler for high fidelity gates between fluxonium qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+H">Helin Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+C">Chunyang Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Weiss%2C+D+K">D. K. Weiss</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ziwen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yuwei Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Guinn%2C+C">Charles Guinn</a>, <a href="/search/quant-ph?searchtype=author&query=Sussman%2C+S">Sara Sussman</a>, <a href="/search/quant-ph?searchtype=author&query=Chitta%2C+S+P">Sai Pavan Chitta</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+D">Danyang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Houck%2C+A+A">Andrew A. Houck</a>, <a href="/search/quant-ph?searchtype=author&query=Koch%2C+J">Jens Koch</a>, <a href="/search/quant-ph?searchtype=author&query=Schuster%2C+D+I">David I. Schuster</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="2309.05720v2-abstract-short" style="display: inline;"> The fluxonium qubit is a promising candidate for quantum computation due to its long coherence times and large anharmonicity. We present a tunable coupler that realizes strong inductive coupling between two heavy-fluxonium qubits, each with $\sim50$MHz frequencies and $\sim5$ GHz anharmonicities. The coupler enables the qubits to have a large tuning range of $\textit{XX}$ coupling strengths (… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.05720v2-abstract-full').style.display = 'inline'; document.getElementById('2309.05720v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.05720v2-abstract-full" style="display: none;"> The fluxonium qubit is a promising candidate for quantum computation due to its long coherence times and large anharmonicity. We present a tunable coupler that realizes strong inductive coupling between two heavy-fluxonium qubits, each with $\sim50$MHz frequencies and $\sim5$ GHz anharmonicities. The coupler enables the qubits to have a large tuning range of $\textit{XX}$ coupling strengths ($-35$ to $75$ MHz). The $\textit{ZZ}$ coupling strength is $<3$kHz across the entire coupler bias range, and $<100$Hz at the coupler off-position. These qualities lead to fast, high-fidelity single- and two-qubit gates. By driving at the difference frequency of the two qubits, we realize a $\sqrt{i\mathrm{SWAP}}$ gate in $258$ns with fidelity $99.72\%$, and by driving at the sum frequency of the two qubits, we achieve a $\sqrt{b\mathrm{SWAP}}$ gate in $102$ns with fidelity $99.91\%$. This latter gate is only 5 qubit Larmor periods in length. We run cross-entropy benchmarking for over $20$ consecutive hours and measure stable gate fidelities, with $\sqrt{b\mathrm{SWAP}}$ drift ($2 蟽$) $< 0.02\%$ and $\sqrt{i\mathrm{SWAP}}$ drift $< 0.08\%$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.05720v2-abstract-full').style.display = 'none'; document.getElementById('2309.05720v2-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> 25 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">16 pages, 14 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/2308.08910">arXiv:2308.08910</a> <span> [<a href="https://arxiv.org/pdf/2308.08910">pdf</a>, <a href="https://arxiv.org/format/2308.08910">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"> Semiquantum key distribution using initial states in only one basis without the classical user measuring </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liang%2C+X">Xueying Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+X">Xiangfu Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+S">Shenggen Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Rong%2C+Z">Zhenbang Rong</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhiming Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jianfeng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Ying Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+J">Jianxiong Wu</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="2308.08910v1-abstract-short" style="display: inline;"> From the perspective of resource theory, it is interesting to achieve the same quantum task using as few quantum resources as possible. Semiquantum key distribution (SQKD), which allows a quantum user to share a confidential key with a classical user who prepares and operates qubits in only one basis, is an important example for studying this issue. To further limit the quantum resources used by u… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.08910v1-abstract-full').style.display = 'inline'; document.getElementById('2308.08910v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.08910v1-abstract-full" style="display: none;"> From the perspective of resource theory, it is interesting to achieve the same quantum task using as few quantum resources as possible. Semiquantum key distribution (SQKD), which allows a quantum user to share a confidential key with a classical user who prepares and operates qubits in only one basis, is an important example for studying this issue. To further limit the quantum resources used by users, in this paper, we constructed the first SQKD protocol which restricts the quantum user to prepare quantum states in only one basis and removes the classical user's measurement capability. Furthermore, we prove that the constructed protocol is unconditionally secure by deriving a key rate expression of the error rate in the asymptotic scenario. The work of this paper provides inspiration for achieving quantum superiority with minimal quantum resources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.08910v1-abstract-full').style.display = 'none'; document.getElementById('2308.08910v1-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> 17 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">13 pages, 3 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/2307.13349">arXiv:2307.13349</a> <span> [<a href="https://arxiv.org/pdf/2307.13349">pdf</a>, <a href="https://arxiv.org/format/2307.13349">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/s41467-023-41903-5">10.1038/s41467-023-41903-5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> In situ electron paramagnetic resonance spectroscopy using single nanodiamond sensors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Qin%2C+Z">Zhuoyang Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhecheng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Kong%2C+F">Fei Kong</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+J">Jia Su</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhehua Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+P">Pengju Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Sanyou Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+F">Fazhan Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+J">Jiangfeng Du</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="2307.13349v1-abstract-short" style="display: inline;"> An ultimate goal of electron paramagnetic resonance (EPR) spectroscopy is to analyze molecular dynamics in place where it occurs, such as in a living cell. The nanodiamond (ND) hosting nitrogen-vacancy (NV) centers will be a promising EPR sensor to achieve this goal. However, ND-based EPR spectroscopy remains elusive, due to the challenge of controlling NV centers without well-defined orientations… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.13349v1-abstract-full').style.display = 'inline'; document.getElementById('2307.13349v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.13349v1-abstract-full" style="display: none;"> An ultimate goal of electron paramagnetic resonance (EPR) spectroscopy is to analyze molecular dynamics in place where it occurs, such as in a living cell. The nanodiamond (ND) hosting nitrogen-vacancy (NV) centers will be a promising EPR sensor to achieve this goal. However, ND-based EPR spectroscopy remains elusive, due to the challenge of controlling NV centers without well-defined orientations inside a flexible ND. Here, we show a generalized zero-field EPR technique with spectra robust to the sensor's orientation. The key is applying an amplitude modulation on the control field, which generates a series of equidistant Floquet states with energy splitting being the orientation-independent modulation frequency. We acquire the zero-field EPR spectrum of vanadyl ions in aqueous glycerol solution with embedded single NDs, paving the way towards \emph{in vivo} EPR. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.13349v1-abstract-full').style.display = 'none'; document.getElementById('2307.13349v1-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> 25 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat. Commun. 14, 6278 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.02705">arXiv:2307.02705</a> <span> [<a href="https://arxiv.org/pdf/2307.02705">pdf</a>, <a href="https://arxiv.org/format/2307.02705">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 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/PhysRevE.109.064111">10.1103/PhysRevE.109.064111 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Integral fluctuation theorems and trace-preserving map </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhiqiang Huang</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="2307.02705v3-abstract-short" style="display: inline;"> The detailed fluctuation theorem implies symmetry in the generating function of entropy production probability. The integral fluctuation theorem directly follows from this symmetry and the normalization of the probability. In this paper, we rewrite the generating function by integrating measurements and evolution into a constructed mapping. This mapping is completely positive, and the original int… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.02705v3-abstract-full').style.display = 'inline'; document.getElementById('2307.02705v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.02705v3-abstract-full" style="display: none;"> The detailed fluctuation theorem implies symmetry in the generating function of entropy production probability. The integral fluctuation theorem directly follows from this symmetry and the normalization of the probability. In this paper, we rewrite the generating function by integrating measurements and evolution into a constructed mapping. This mapping is completely positive, and the original integral FT is determined by the trace-preserving property of these constructed maps. We illustrate the convenience of this method by discussing the eigenstate fluctuation theorem and heat exchange between two baths. This set of methods is also applicable to the generating functions of quasi-probability, where we observe the Petz recovery map arising naturally from this approach. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.02705v3-abstract-full').style.display = 'none'; document.getElementById('2307.02705v3-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">16 pages, 1 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. E 109, 064111 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.03965">arXiv:2305.03965</a> <span> [<a href="https://arxiv.org/pdf/2305.03965">pdf</a>, <a href="https://arxiv.org/ps/2305.03965">ps</a>, <a href="https://arxiv.org/format/2305.03965">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/PhysRevA.108.032217">10.1103/PhysRevA.108.032217 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multiple entropy production for multitime quantum processes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhiqiang Huang</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="2305.03965v2-abstract-short" style="display: inline;"> Entropy production and the detailed fluctuation theorem are of fundamental importance for thermodynamic processes. In this paper, we study the multiple entropy production for multitime quantum processes in a unified framework. For closed quantum systems and Markovian open quantum systems, the given entropy productions all satisfy the detailed fluctuation relation. This also shows that the entropy… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.03965v2-abstract-full').style.display = 'inline'; document.getElementById('2305.03965v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.03965v2-abstract-full" style="display: none;"> Entropy production and the detailed fluctuation theorem are of fundamental importance for thermodynamic processes. In this paper, we study the multiple entropy production for multitime quantum processes in a unified framework. For closed quantum systems and Markovian open quantum systems, the given entropy productions all satisfy the detailed fluctuation relation. This also shows that the entropy production rate under these processes is non-negative. For non-Markovian open quantum systems, the memory effect can lead to a negative entropy production rate. Thus, in general, the entropy production of the marginal distribution does not satisfy the detailed FT relation. Our framework can be applied to a wide range of physical systems and dynamics. It provides a systematic tool for studying entropy production and its rate under arbitrary quantum processes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.03965v2-abstract-full').style.display = 'none'; document.getElementById('2305.03965v2-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> 25 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">16 pages, 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. A 108, 032217 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.13257">arXiv:2304.13257</a> <span> [<a href="https://arxiv.org/pdf/2304.13257">pdf</a>, <a href="https://arxiv.org/format/2304.13257">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="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</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/s41534-024-00840-x">10.1038/s41534-024-00840-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Systematic Improvements in Transmon Qubit Coherence Enabled by Niobium Surface Encapsulation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Bal%2C+M">Mustafa Bal</a>, <a href="/search/quant-ph?searchtype=author&query=Murthy%2C+A+A">Akshay A. Murthy</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+S">Shaojiang Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Crisa%2C+F">Francesco Crisa</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+X">Xinyuan You</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ziwen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Roy%2C+T">Tanay Roy</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+J">Jaeyel Lee</a>, <a href="/search/quant-ph?searchtype=author&query=van+Zanten%2C+D">David van Zanten</a>, <a href="/search/quant-ph?searchtype=author&query=Pilipenko%2C+R">Roman Pilipenko</a>, <a href="/search/quant-ph?searchtype=author&query=Nekrashevich%2C+I">Ivan Nekrashevich</a>, <a href="/search/quant-ph?searchtype=author&query=Lunin%2C+A">Andrei Lunin</a>, <a href="/search/quant-ph?searchtype=author&query=Bafia%2C+D">Daniel Bafia</a>, <a href="/search/quant-ph?searchtype=author&query=Krasnikova%2C+Y">Yulia Krasnikova</a>, <a href="/search/quant-ph?searchtype=author&query=Kopas%2C+C+J">Cameron J. Kopas</a>, <a href="/search/quant-ph?searchtype=author&query=Lachman%2C+E+O">Ella O. Lachman</a>, <a href="/search/quant-ph?searchtype=author&query=Miller%2C+D">Duncan Miller</a>, <a href="/search/quant-ph?searchtype=author&query=Mutus%2C+J+Y">Josh Y. Mutus</a>, <a href="/search/quant-ph?searchtype=author&query=Reagor%2C+M+J">Matthew J. Reagor</a>, <a href="/search/quant-ph?searchtype=author&query=Cansizoglu%2C+H">Hilal Cansizoglu</a>, <a href="/search/quant-ph?searchtype=author&query=Marshall%2C+J">Jayss Marshall</a>, <a href="/search/quant-ph?searchtype=author&query=Pappas%2C+D+P">David P. Pappas</a>, <a href="/search/quant-ph?searchtype=author&query=Vu%2C+K">Kim Vu</a>, <a href="/search/quant-ph?searchtype=author&query=Yadavalli%2C+K">Kameshwar Yadavalli</a>, <a href="/search/quant-ph?searchtype=author&query=Oh%2C+J">Jin-Su Oh</a> , et al. (15 additional authors not shown) </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="2304.13257v3-abstract-short" style="display: inline;"> We present a novel transmon qubit fabrication technique that yields systematic improvements in T$_1$ relaxation times. We fabricate devices using an encapsulation strategy that involves passivating the surface of niobium and thereby preventing the formation of its lossy surface oxide. By maintaining the same superconducting metal and only varying the surface structure, this comparative investigati… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.13257v3-abstract-full').style.display = 'inline'; document.getElementById('2304.13257v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.13257v3-abstract-full" style="display: none;"> We present a novel transmon qubit fabrication technique that yields systematic improvements in T$_1$ relaxation times. We fabricate devices using an encapsulation strategy that involves passivating the surface of niobium and thereby preventing the formation of its lossy surface oxide. By maintaining the same superconducting metal and only varying the surface structure, this comparative investigation examining different capping materials, such as tantalum, aluminum, titanium nitride, and gold, and film substrates across different qubit foundries definitively demonstrates the detrimental impact that niobium oxides have on the coherence times of superconducting qubits, compared to native oxides of tantalum, aluminum or titanium nitride. Our surface-encapsulated niobium qubit devices exhibit T$_1$ relaxation times 2 to 5 times longer than baseline niobium qubit devices with native niobium oxides. When capping niobium with tantalum, we obtain median qubit lifetimes above 300 microseconds, with maximum values up to 600 microseconds, that represent the highest lifetimes to date for superconducting qubits prepared on both sapphire and silicon. Our comparative structural and chemical analysis suggests why amorphous niobium oxides may induce higher losses compared to other amorphous oxides. These results are in line with high-accuracy measurements of the niobium oxide loss tangent obtained with ultra-high Q superconducting radiofrequency (SRF) cavities. This new surface encapsulation strategy enables even further reduction of dielectric losses via passivation with ambient-stable materials, while preserving fabrication and scalable manufacturability thanks to the compatibility with silicon processes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.13257v3-abstract-full').style.display = 'none'; document.getElementById('2304.13257v3-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 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">Journal ref:</span> npj Quantum Inf 10, 43 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.11491">arXiv:2303.11491</a> <span> [<a href="https://arxiv.org/pdf/2303.11491">pdf</a>, <a href="https://arxiv.org/format/2303.11491">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/10.22331/q-2023-11-03-1158">10.22331/q-2023-11-03-1158 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Completely Positive Map for Noisy Driven Quantum Systems Derived by Keldysh Expansion </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ziwen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Y">Yunwei Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Grassellino%2C+A">Anna Grassellino</a>, <a href="/search/quant-ph?searchtype=author&query=Romanenko%2C+A">Alexander Romanenko</a>, <a href="/search/quant-ph?searchtype=author&query=Koch%2C+J">Jens Koch</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+S">Shaojiang Zhu</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="2303.11491v4-abstract-short" style="display: inline;"> Accurate modeling of decoherence errors in quantum processors is crucial for analyzing and improving gate fidelities. To increase the accuracy beyond that of the Lindblad dynamical map, several generalizations have been proposed, and the exploration of simpler and more systematic frameworks is still ongoing. In this paper, we introduce a decoherence model based on the Keldysh formalism. This forma… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.11491v4-abstract-full').style.display = 'inline'; document.getElementById('2303.11491v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.11491v4-abstract-full" style="display: none;"> Accurate modeling of decoherence errors in quantum processors is crucial for analyzing and improving gate fidelities. To increase the accuracy beyond that of the Lindblad dynamical map, several generalizations have been proposed, and the exploration of simpler and more systematic frameworks is still ongoing. In this paper, we introduce a decoherence model based on the Keldysh formalism. This formalism allows us to include non-periodic drives and correlated quantum noise in our model. In addition to its wide range of applications, our method is also numerically simple, and yields a CPTP map. These features allow us to integrate the Keldysh map with quantum-optimal-control techniques. We demonstrate that this strategy generates pulses that mitigate correlated quantum noise in qubit state-transfer and gate operations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.11491v4-abstract-full').style.display = 'none'; document.getElementById('2303.11491v4-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> 25 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 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">Report number:</span> FERMILAB-PUB-23-141-SQMS-TD </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum 7, 1158 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.13396">arXiv:2211.13396</a> <span> [<a href="https://arxiv.org/pdf/2211.13396">pdf</a>, <a href="https://arxiv.org/ps/2211.13396">ps</a>, <a href="https://arxiv.org/format/2211.13396">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"> Leggett-Garg inequalities for multitime processes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhiqiang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+X">Xiao-Kan Guo</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="2211.13396v3-abstract-short" style="display: inline;"> We study some aspects of the Leggett-Garg inequalities by using the operator-state formalism for multitime processes. The process tensor in its Choi-state form, which we call process state, is employed to investigate the Leggett-Garg inequalities and their violations. We find the sufficient conditions on process states for the Leggett-Garg inequalities to hold, based on which we find a new way of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.13396v3-abstract-full').style.display = 'inline'; document.getElementById('2211.13396v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.13396v3-abstract-full" style="display: none;"> We study some aspects of the Leggett-Garg inequalities by using the operator-state formalism for multitime processes. The process tensor in its Choi-state form, which we call process state, is employed to investigate the Leggett-Garg inequalities and their violations. We find the sufficient conditions on process states for the Leggett-Garg inequalities to hold, based on which we find a new way of characterizing the influences on the violation of Leggett-Garg inequalities through the structure of process states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.13396v3-abstract-full').style.display = 'none'; document.getElementById('2211.13396v3-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> 19 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.08896">arXiv:2211.08896</a> <span> [<a href="https://arxiv.org/pdf/2211.08896">pdf</a>, <a href="https://arxiv.org/format/2211.08896">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"> Sideband Cooling of a Trapped Ion in Strong Sideband Coupling Regime </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhuo-Peng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Tian%2C+T">Tian-Ci Tian</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Z">Zheng-Yang Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jian-Qi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Bao%2C+W">Wan-Su Bao</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+C">Chu Guo</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="2211.08896v1-abstract-short" style="display: inline;"> Conventional theoretical studies on the ground-state laser cooling of a trapped ion have mostly focused on the weak sideband coupling (WSC) regime, where the cooling rate is inverse proportional to the linewidth of the excited state. In a recent work~[New J. Phys. 23, 023018 (2021)], we proposed a theoretical framework to study the ground state cooling of a trapped ion in the strong sideband coupl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.08896v1-abstract-full').style.display = 'inline'; document.getElementById('2211.08896v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.08896v1-abstract-full" style="display: none;"> Conventional theoretical studies on the ground-state laser cooling of a trapped ion have mostly focused on the weak sideband coupling (WSC) regime, where the cooling rate is inverse proportional to the linewidth of the excited state. In a recent work~[New J. Phys. 23, 023018 (2021)], we proposed a theoretical framework to study the ground state cooling of a trapped ion in the strong sideband coupling (SSC) regime, under the assumption of a vanishing carrier transition. Here we extend this analysis to more general situations with nonvanishing carrier transitions, where we show that by properly tuning the coupling lasers a cooling rate proportional to the linewidth can be achieved. Our theoretical predictions closely agree with the corresponding exact solutions in the SSC regime, which provide an important theoretical guidance for sideband cooling experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.08896v1-abstract-full').style.display = 'none'; document.getElementById('2211.08896v1-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> 16 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">7 pages, 4 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/2211.06050">arXiv:2211.06050</a> <span> [<a href="https://arxiv.org/pdf/2211.06050">pdf</a>, <a href="https://arxiv.org/format/2211.06050">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</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/PhysRevA.107.022409">10.1103/PhysRevA.107.022409 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ultimate limits of exoplanet spectroscopy: a quantum approach </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zixin Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Schwab%2C+C">Christian Schwab</a>, <a href="/search/quant-ph?searchtype=author&query=Lupo%2C+C">Cosmo Lupo</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="2211.06050v1-abstract-short" style="display: inline;"> One of the big challenges in exoplanet science is to determine the atmospheric makeup of extrasolar planets, and to find biosignatures that hint at the existence of biochemical processes on another world. The biomarkers we are trying to detect are gases in the exoplanet atmosphere like oxygen or methane, which have deep absorption features in the visible and near-infrared spectrum. Here we establi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.06050v1-abstract-full').style.display = 'inline'; document.getElementById('2211.06050v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.06050v1-abstract-full" style="display: none;"> One of the big challenges in exoplanet science is to determine the atmospheric makeup of extrasolar planets, and to find biosignatures that hint at the existence of biochemical processes on another world. The biomarkers we are trying to detect are gases in the exoplanet atmosphere like oxygen or methane, which have deep absorption features in the visible and near-infrared spectrum. Here we establish the ultimate quantum limit for determining the presence or absence of a spectral absorption line, for a dim source in the presence of a much brighter stellar source. We characterise the associated error exponent in both the frameworks of symmetric and asymmetric hypothesis testing. We found that a structured measurement based on spatial demultiplexing allows us to decouple the light coming from the planet and achieve the ultimate quantum limits. If the planet has intensity $蔚\ll 1$ relative to the star, we show that this approach significantly outperforms direct spectroscopy yielding an improvement of the error exponent by a factor $1/蔚$. We find the optimal measurement, which is a combination of interferometric techniques and spectrum analysis. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.06050v1-abstract-full').style.display = 'none'; document.getElementById('2211.06050v1-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 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">9 pages, 5 figures, and appendix; comments are welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.12732">arXiv:2210.12732</a> <span> [<a href="https://arxiv.org/pdf/2210.12732">pdf</a>, <a href="https://arxiv.org/format/2210.12732">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> </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.107.052205">10.1103/PhysRevA.107.052205 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum circuit for measuring an operator's generalized expectation values and its applications to non-Hermitian winding numbers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ze-Hao Huang</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+P">Peng He</a>, <a href="/search/quant-ph?searchtype=author&query=Lang%2C+L">Li-Jun Lang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+S">Shi-Liang Zhu</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="2210.12732v2-abstract-short" style="display: inline;"> We propose a general quantum circuit based on the swap test for measuring the quantity $\langle 蠄_1 | A | 蠄_2 \rangle$ of an arbitrary operator $A$ with respect to two quantum states $|蠄_{1,2}\rangle$. This quantity is frequently encountered in many fields of physics, and we dub it the generalized expectation as a two-state generalization of the conventional expectation. We apply the circuit, in t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.12732v2-abstract-full').style.display = 'inline'; document.getElementById('2210.12732v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.12732v2-abstract-full" style="display: none;"> We propose a general quantum circuit based on the swap test for measuring the quantity $\langle 蠄_1 | A | 蠄_2 \rangle$ of an arbitrary operator $A$ with respect to two quantum states $|蠄_{1,2}\rangle$. This quantity is frequently encountered in many fields of physics, and we dub it the generalized expectation as a two-state generalization of the conventional expectation. We apply the circuit, in the field of non-Hermitian physics, to the measurement of generalized expectations with respect to left and right eigenstates of a given non-Hermitian Hamiltonian. To efficiently prepare the left and right eigenstates as the input to the general circuit, we also develop a quantum circuit via effectively rotating the Hamiltonian pair $(H,-H^\dagger)$ in the complex plane. As applications, we demonstrate the validity of these circuits in the prototypical Su-Schrieffer-Heeger model with nonreciprocal hopping by measuring the Bloch and non-Bloch spin textures and the corresponding winding numbers under periodic and open boundary conditions (PBCs and OBCs), respectively. The numerical simulation shows that non-Hermitian spin textures building up these winding numbers can be well captured with high fidelity, and the distinct topological phase transitions between PBCs and OBCs are clearly characterized. We may expect that other non-Hermitian topological invariants composed of non-Hermitian spin textures, such as non-Hermitian Chern numbers, and even significant generalized expectations in other branches of physics would also be measured by our general circuit, providing a different perspective to study novel properties in non-Hermitian as well as other physics realized in qubit systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.12732v2-abstract-full').style.display = 'none'; document.getElementById('2210.12732v2-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 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">6+3 pages, 4+1 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. A 107, 052205 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.06897">arXiv:2210.06897</a> <span> [<a href="https://arxiv.org/pdf/2210.06897">pdf</a>, <a href="https://arxiv.org/format/2210.06897">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/acf9c7">10.1088/2058-9565/acf9c7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Orbital Expansion Variational Quantum Eigensolver: Enabling Efficient Simulation of Molecules with Shallow Quantum Circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yusen Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zigeng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+J">Jinzhao Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+X">Xiao Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J+B">Jingbo B. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Lv%2C+D">Dingshun Lv</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="2210.06897v1-abstract-short" style="display: inline;"> In the noisy-intermediate-scale-quantum era, Variational Quantum Eigensolver (VQE) is a promising method to study ground state properties in quantum chemistry, materials science, and condensed physics. However, general quantum eigensolvers are lack of systematical improvability, and achieve rigorous convergence is generally hard in practice, especially in solving strong-correlated systems. Here, w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.06897v1-abstract-full').style.display = 'inline'; document.getElementById('2210.06897v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.06897v1-abstract-full" style="display: none;"> In the noisy-intermediate-scale-quantum era, Variational Quantum Eigensolver (VQE) is a promising method to study ground state properties in quantum chemistry, materials science, and condensed physics. However, general quantum eigensolvers are lack of systematical improvability, and achieve rigorous convergence is generally hard in practice, especially in solving strong-correlated systems. Here, we propose an Orbital Expansion VQE~(OE-VQE) framework to construct an efficient convergence path. The path starts from a highly correlated compact active space and rapidly expands and converges to the ground state, enabling simulating ground states with much shallower quantum circuits. We benchmark the OE-VQE on a series of typical molecules including H$_{6}$-chain, H$_{10}$-ring and N$_2$, and the simulation results show that proposed convergence paths dramatically enhance the performance of general quantum eigensolvers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.06897v1-abstract-full').style.display = 'none'; document.getElementById('2210.06897v1-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 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">Wu et al 2023 Quantum Sci. Technol</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.03738">arXiv:2208.03738</a> <span> [<a href="https://arxiv.org/pdf/2208.03738">pdf</a>, <a href="https://arxiv.org/format/2208.03738">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"> Experimental verification of the treatment of time-dependent flux in circuit quantization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Bryon%2C+J">Jacob Bryon</a>, <a href="/search/quant-ph?searchtype=author&query=Weiss%2C+D+K">D. K. Weiss</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+X">Xinyuan You</a>, <a href="/search/quant-ph?searchtype=author&query=Sussman%2C+S">Sara Sussman</a>, <a href="/search/quant-ph?searchtype=author&query=Croot%2C+X">Xanthe Croot</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ziwen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Koch%2C+J">Jens Koch</a>, <a href="/search/quant-ph?searchtype=author&query=Houck%2C+A">Andrew Houck</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="2208.03738v1-abstract-short" style="display: inline;"> Recent theoretical work has highlighted that quantizing a superconducting circuit in the presence of time-dependent flux $桅(t)$ generally produces Hamiltonian terms proportional to $d桅/dt$ unless a special allocation of the flux across inductive terms is chosen. Here, we present an experiment probing the effects of a fast flux ramp applied to a heavy-fluxonium circuit. The experiment confirms that… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.03738v1-abstract-full').style.display = 'inline'; document.getElementById('2208.03738v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.03738v1-abstract-full" style="display: none;"> Recent theoretical work has highlighted that quantizing a superconducting circuit in the presence of time-dependent flux $桅(t)$ generally produces Hamiltonian terms proportional to $d桅/dt$ unless a special allocation of the flux across inductive terms is chosen. Here, we present an experiment probing the effects of a fast flux ramp applied to a heavy-fluxonium circuit. The experiment confirms that na茂ve omission of the $d桅/dt$ term leads to theoretical predictions inconsistent with experimental data. Experimental data are fully consistent with recent theory that includes the derivative term or equivalently uses "irrotational variables" that uniquely allocate the flux to properly eliminate the $d桅/dt$ term. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.03738v1-abstract-full').style.display = 'none'; document.getElementById('2208.03738v1-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 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> Phys. Rev. Applied 19, 034031 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.02470">arXiv:2207.02470</a> <span> [<a href="https://arxiv.org/pdf/2207.02470">pdf</a>, <a href="https://arxiv.org/ps/2207.02470">ps</a>, <a href="https://arxiv.org/format/2207.02470">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/10.1016/j.physleta.2023.129204">10.1016/j.physleta.2023.129204 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> On the relation between quantum Darwinism and approximate quantum Markovianity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+X">Xiao-Kan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhiqiang Huang</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="2207.02470v3-abstract-short" style="display: inline;"> There are strong evidences in the literature that quantum non-Markovianity would hinder the presence of Quantum Darwinism. In this Letter, we study the relation between quantum Darwinism and approximate quantum Markovianity for open quantum systems by exploiting the properties of quantum conditional mutual information. We show that for approximately Markovian quantum processes the conditional mutu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.02470v3-abstract-full').style.display = 'inline'; document.getElementById('2207.02470v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.02470v3-abstract-full" style="display: none;"> There are strong evidences in the literature that quantum non-Markovianity would hinder the presence of Quantum Darwinism. In this Letter, we study the relation between quantum Darwinism and approximate quantum Markovianity for open quantum systems by exploiting the properties of quantum conditional mutual information. We show that for approximately Markovian quantum processes the conditional mutual information still has the scaling property for Quantum Darwinism. Then two general bounds on the backflow of information are obtained, with which we can show that the presence of Quantum Darwinism restricts the information backflow and the quantum non-Markovianity must be small. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.02470v3-abstract-full').style.display = 'none'; document.getElementById('2207.02470v3-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 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">8 pages, typos fixed</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physics Letters A 491,129204 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.00557">arXiv:2207.00557</a> <span> [<a href="https://arxiv.org/pdf/2207.00557">pdf</a>, <a href="https://arxiv.org/format/2207.00557">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="General Relativity and Quantum Cosmology">gr-qc</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/s41534-023-00702-y">10.1038/s41534-023-00702-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental Simulation of Loop Quantum Gravity on a Photonic Chip </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=van+der+Meer%2C+R">Reinier van der Meer</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zichang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Anguita%2C+M+C">Malaquias Correa Anguita</a>, <a href="/search/quant-ph?searchtype=author&query=Qu%2C+D">Dongxue Qu</a>, <a href="/search/quant-ph?searchtype=author&query=Hooijschuur%2C+P">Peter Hooijschuur</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Hongguang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+M">Muxin Han</a>, <a href="/search/quant-ph?searchtype=author&query=Renema%2C+J+J">Jelmer J. Renema</a>, <a href="/search/quant-ph?searchtype=author&query=Cohen%2C+L">Lior Cohen</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="2207.00557v1-abstract-short" style="display: inline;"> The unification of general relativity and quantum theory is one of the fascinating problems of modern physics. One leading solution is Loop Quantum Gravity (LQG). Simulating LQG may be important for providing predictions which can then be tested experimentally. However, such complex quantum simulations cannot run efficiently on classical computers, and quantum computers or simulators are needed. H… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.00557v1-abstract-full').style.display = 'inline'; document.getElementById('2207.00557v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.00557v1-abstract-full" style="display: none;"> The unification of general relativity and quantum theory is one of the fascinating problems of modern physics. One leading solution is Loop Quantum Gravity (LQG). Simulating LQG may be important for providing predictions which can then be tested experimentally. However, such complex quantum simulations cannot run efficiently on classical computers, and quantum computers or simulators are needed. Here, we experimentally demonstrate quantum simulations of spinfoam amplitudes of LQG on an integrated photonics quantum processor. We simulate a basic transition of LQG and show that the derived spinfoam vertex amplitude falls within 4% error with respect to the theoretical prediction, despite experimental imperfections. We also discuss how to generalize the simulation for more complex transitions, in realistic experimental conditions, which will eventually lead to a quantum advantage demonstration as well as expand the toolbox to investigate LQG. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.00557v1-abstract-full').style.display = 'none'; document.getElementById('2207.00557v1-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> 1 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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 pages, 4 figures. comments are welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.10800">arXiv:2206.10800</a> <span> [<a href="https://arxiv.org/pdf/2206.10800">pdf</a>, <a href="https://arxiv.org/ps/2206.10800">ps</a>, <a href="https://arxiv.org/format/2206.10800">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/PhysRevA.106.042412">10.1103/PhysRevA.106.042412 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Classical and quantum parts of conditional mutual information for open quantum systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhiqiang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+X">Xiao-Kan Guo</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="2206.10800v3-abstract-short" style="display: inline;"> We study the classical, classical-quantum, and quantum parts of conditional mutual information in the ``system-environment-ancilla'' setting of open quantum systems. We perform the separation of conditional mutual information by generalizing the classification of correlations of quantum states. The condition for identifying the classical part of conditional mutual information is given by adapting… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.10800v3-abstract-full').style.display = 'inline'; document.getElementById('2206.10800v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.10800v3-abstract-full" style="display: none;"> We study the classical, classical-quantum, and quantum parts of conditional mutual information in the ``system-environment-ancilla'' setting of open quantum systems. We perform the separation of conditional mutual information by generalizing the classification of correlations of quantum states. The condition for identifying the classical part of conditional mutual information is given by adapting the no-local-broadcasting theorem to this setting, while the condition for classical-quantum part of conditional mutual information is obtained by considering the multipartite quantum discord and the no-unilocal-broadcasting theorem. For the quantum part of conditional mutual information, we further generalize the characterization of entanglement by quantum discord of state extensions to the multipatite setting, so as to derive a generalized Koashi-Winter-type monogamy equality for conditional mutual information. Our results have explicit dependence on the extensions of environment, which are useful for studying different environmental contributions to the quantum non-Markovianity of open quantum systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.10800v3-abstract-full').style.display = 'none'; document.getElementById('2206.10800v3-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 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 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">24 pages, 1 figure</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 106, 042412 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.10669">arXiv:2206.10669</a> <span> [<a href="https://arxiv.org/pdf/2206.10669">pdf</a>, <a href="https://arxiv.org/format/2206.10669">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/PhysRevApplied.18.044026">10.1103/PhysRevApplied.18.044026 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Stabilizing and improving qubit coherence by engineering noise spectrum of two-level systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=You%2C+X">Xinyuan You</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ziwen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Alyanak%2C+U">Ugur Alyanak</a>, <a href="/search/quant-ph?searchtype=author&query=Romanenko%2C+A">Alexander Romanenko</a>, <a href="/search/quant-ph?searchtype=author&query=Grassellino%2C+A">Anna Grassellino</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+S">Shaojiang Zhu</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="2206.10669v2-abstract-short" style="display: inline;"> Superconducting circuits are a leading platform for quantum computing. However, their coherence times are still limited and exhibit temporal fluctuations. Those phenomena are often attributed to the coupling between qubits and material defects that can be well described as an ensemble of two-level systems (TLSs). Among them, charge fluctuators inside amorphous oxide layers contribute to both low-f… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.10669v2-abstract-full').style.display = 'inline'; document.getElementById('2206.10669v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.10669v2-abstract-full" style="display: none;"> Superconducting circuits are a leading platform for quantum computing. However, their coherence times are still limited and exhibit temporal fluctuations. Those phenomena are often attributed to the coupling between qubits and material defects that can be well described as an ensemble of two-level systems (TLSs). Among them, charge fluctuators inside amorphous oxide layers contribute to both low-frequency $1/f$ charge noise and high-frequency dielectric loss, causing fast qubit dephasing and relaxation. Moreover, spectral diffusion from mutual TLS interactions varies the noise amplitude over time, fluctuating the qubit lifetime. Here, we propose to mitigate those harmful effects by engineering the relevant TLS noise spectral densities. Specifically, our protocols smooth the high-frequency noise spectrum and suppress the low-frequency noise amplitude via depolarizing and dephasing the TLSs, respectively. As a result, we predict a drastic stabilization in qubit lifetime and an increase in qubit pure dephasing time. Our detailed analysis of feasible experimental implementations shows that the improvement is not compromised by spurious coupling from the applied noise to the qubit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.10669v2-abstract-full').style.display = 'none'; document.getElementById('2206.10669v2-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 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 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">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> Phys. Rev. Applied 18, 044026 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.10097">arXiv:2206.10097</a> <span> [<a href="https://arxiv.org/pdf/2206.10097">pdf</a>, <a href="https://arxiv.org/ps/2206.10097">ps</a>, <a href="https://arxiv.org/format/2206.10097">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/10.1142/9789811272158_0010">10.1142/9789811272158_0010 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Energy functionals of single-particle densities: A unified view </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Englert%2C+B">Berthold-Georg Englert</a>, <a href="/search/quant-ph?searchtype=author&query=Hue%2C+J+H">Jun Hao Hue</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z+C">Zi Chao Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Paraniak%2C+M+M">Miko艂aj M. Paraniak</a>, <a href="/search/quant-ph?searchtype=author&query=Trappe%2C+M">Martin-Isbj枚rn Trappe</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="2206.10097v2-abstract-short" style="display: inline;"> Density functional theory is usually formulated in terms of the density in configuration space. Functionals of the momentum-space density have also been studied, and yet other densities could be considered. We offer a unified view from a second-quantized perspective and introduce a version of density functional theory that treats all single-particle contributions to the energy exactly. An appendix… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.10097v2-abstract-full').style.display = 'inline'; document.getElementById('2206.10097v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.10097v2-abstract-full" style="display: none;"> Density functional theory is usually formulated in terms of the density in configuration space. Functionals of the momentum-space density have also been studied, and yet other densities could be considered. We offer a unified view from a second-quantized perspective and introduce a version of density functional theory that treats all single-particle contributions to the energy exactly. An appendix deals with semiclassical eigenvalues. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.10097v2-abstract-full').style.display = 'none'; document.getElementById('2206.10097v2-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> 23 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 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">A contribution to the Proceedings of the Workshop on Density Functionals for Many-Particle Systems, 2-27 September 2019, Singapore; 22 pages, no 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/2206.08533">arXiv:2206.08533</a> <span> [<a href="https://arxiv.org/pdf/2206.08533">pdf</a>, <a href="https://arxiv.org/format/2206.08533">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/10.1126/sciadv.abq8158">10.1126/sciadv.abq8158 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Picotesla magnetometry of microwave fields with diamond sensors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhecheng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Kong%2C+F">Fei Kong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+P">Pengju Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhehuang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+P">Pei Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Ya Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+F">Fazhan Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+J">Jiangfeng Du</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="2206.08533v2-abstract-short" style="display: inline;"> Developing robust microwave-field sensors is both fundamentally and practically important with a wide range of applications from astronomy to communication engineering. The Nitrogen-Vacancy (NV) center in diamond is an attractive candidate for such purpose because of its magnetometric sensitivity, stability and compatibility with ambient conditions. However, the existing NV center-based magnetomet… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.08533v2-abstract-full').style.display = 'inline'; document.getElementById('2206.08533v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.08533v2-abstract-full" style="display: none;"> Developing robust microwave-field sensors is both fundamentally and practically important with a wide range of applications from astronomy to communication engineering. The Nitrogen-Vacancy (NV) center in diamond is an attractive candidate for such purpose because of its magnetometric sensitivity, stability and compatibility with ambient conditions. However, the existing NV center-based magnetometers have limited sensitivity in the microwave band. Here we present a continuous heterodyne detection method that can enhance the sensor's response to weak microwaves, even in the absence of spin controls. Experimentally, we achieve a sensitivity of 8.9 pT$\cdot$Hz$^{-1/2}$ for microwaves of 2.9 GHz by simultaneously using an ensemble of $n_{\text{NV}} \sim 2.8\times10^{13}$ NV centers within a sensor volume of $4\times10^{-2}$ mm$^3$. Besides, we also achieve $1/t$ scaling of frequency resolution up to measurement time $t$ of 10000 s. Our method removes the control pulses and thus will greatly benefit the practical application of diamond-based microwave sensors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.08533v2-abstract-full').style.display = 'none'; document.getElementById('2206.08533v2-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 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 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">7 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Sci. Adv. 8, eabq8158 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.08320">arXiv:2206.08320</a> <span> [<a href="https://arxiv.org/pdf/2206.08320">pdf</a>, <a href="https://arxiv.org/format/2206.08320">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"> Computer-aided quantization and numerical analysis of superconducting circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chitta%2C+S+P">Sai Pavan Chitta</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+T">Tianpu Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ziwen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Mondragon-Shem%2C+I">Ian Mondragon-Shem</a>, <a href="/search/quant-ph?searchtype=author&query=Koch%2C+J">Jens Koch</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="2206.08320v2-abstract-short" style="display: inline;"> The development of new superconducting circuits and the improvement of existing ones rely on the accurate modeling of spectral properties which are key to achieving the needed advances in qubit performance. Systematic circuit analysis at the lumped-element level, starting from a circuit network and culminating in a Hamiltonian appropriately describing the quantum properties of the circuit, is a we… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.08320v2-abstract-full').style.display = 'inline'; document.getElementById('2206.08320v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.08320v2-abstract-full" style="display: none;"> The development of new superconducting circuits and the improvement of existing ones rely on the accurate modeling of spectral properties which are key to achieving the needed advances in qubit performance. Systematic circuit analysis at the lumped-element level, starting from a circuit network and culminating in a Hamiltonian appropriately describing the quantum properties of the circuit, is a well-established procedure, yet cumbersome to carry out manually for larger circuits. We present work utilizing symbolic computer algebra and numerical diagonalization routines versatile enough to tackle a variety of circuits. Results from this work are accessible through a newly released module of the scqubits package. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.08320v2-abstract-full').style.display = 'none'; document.getElementById('2206.08320v2-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 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 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">12 pages, 7 figures, 1 table, associated Python package: https://github.com/scqubits/scqubits, added references, corrected typos and updated numerical values</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> New J. Phys. 24 103020 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.02827">arXiv:2206.02827</a> <span> [<a href="https://arxiv.org/pdf/2206.02827">pdf</a>, <a href="https://arxiv.org/format/2206.02827">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/PhysRevApplied.18.L061001">10.1103/PhysRevApplied.18.L061001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High-Order Qubit Dephasing at Sweet Spots by Non-Gaussian Fluctuators: Symmetry Breaking and Floquet Protection </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ziwen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+X">Xinyuan You</a>, <a href="/search/quant-ph?searchtype=author&query=Alyanak%2C+U">Ugur Alyanak</a>, <a href="/search/quant-ph?searchtype=author&query=Romanenko%2C+A">Alexander Romanenko</a>, <a href="/search/quant-ph?searchtype=author&query=Grassellino%2C+A">Anna Grassellino</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+S">Shaojiang Zhu</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="2206.02827v1-abstract-short" style="display: inline;"> Although the Gaussian-noise assumption is widely adopted in the study of qubit decoherence, non-Gaussian noise sources, especially the strong discrete fluctuators, have been detected in many qubits. It remains an important task to further understand and mitigate the distinctive decoherence effect of the non-Gaussian noise. Here, we study the qubit dephasing caused by the non-Gaussian fluctuators,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.02827v1-abstract-full').style.display = 'inline'; document.getElementById('2206.02827v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.02827v1-abstract-full" style="display: none;"> Although the Gaussian-noise assumption is widely adopted in the study of qubit decoherence, non-Gaussian noise sources, especially the strong discrete fluctuators, have been detected in many qubits. It remains an important task to further understand and mitigate the distinctive decoherence effect of the non-Gaussian noise. Here, we study the qubit dephasing caused by the non-Gaussian fluctuators, and predict a symmetry-breaking effect that is unique to the non-Gaussian noise. This broken symmetry results in an experimentally measurable mismatch between the extremum points of the dephasing rate and qubit frequency, which demands extra carefulness in characterizing the noise and locating the optimal working point. To further enhance the coherence time at the sweet spot, we propose to suppress the second-order derivative of the qubit frequency by the Floquet engineering. Our simulation with a heavy fluxonium shows an order of magnitude improvement of the dephasing time, even after including the noise introduced by the drive. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.02827v1-abstract-full').style.display = 'none'; document.getElementById('2206.02827v1-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2205.13500">arXiv:2205.13500</a> <span> [<a href="https://arxiv.org/pdf/2205.13500">pdf</a>, <a href="https://arxiv.org/ps/2205.13500">ps</a>, <a href="https://arxiv.org/format/2205.13500">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"> Quantum generative adversarial learning for simultaneous multiparameter estimation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zichao Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yuanyuan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lixiang Chen</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="2205.13500v1-abstract-short" style="display: inline;"> Generative adversarial learning is currently one of the most prolific fields in artificial intelligence due to its great performance in a variety of challenging tasks such as photorealistic image and video generation. While a quantum version of generative adversarial learning has emerged that promises exponential advantages over its classical counterpart, its experimental implementation and potent… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.13500v1-abstract-full').style.display = 'inline'; document.getElementById('2205.13500v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2205.13500v1-abstract-full" style="display: none;"> Generative adversarial learning is currently one of the most prolific fields in artificial intelligence due to its great performance in a variety of challenging tasks such as photorealistic image and video generation. While a quantum version of generative adversarial learning has emerged that promises exponential advantages over its classical counterpart, its experimental implementation and potential applications with accessible quantum technologies remain explored little. Here, we report an experimental demonstration of quantum generative adversarial learning with the assistance of adaptive feedback that is based on stochastic gradient descent algorithm. Its performance is explored by applying this technique to the adaptive characterization of quantum dynamics and simultaneous estimation of multiple phases. These results indicate the intriguing advantages of quantum generative adversarial learning even in the presence of deleterious noise, and pave the way towards quantum-enhanced information processing applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.13500v1-abstract-full').style.display = 'none'; document.getElementById('2205.13500v1-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 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/2205.08679">arXiv:2205.08679</a> <span> [<a href="https://arxiv.org/pdf/2205.08679">pdf</a>, <a href="https://arxiv.org/ps/2205.08679">ps</a>, <a href="https://arxiv.org/format/2205.08679">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> </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/10.1016/j.physleta.2022.128553">10.1016/j.physleta.2022.128553 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Generalizations of Berry phase and differentiation of purified state and thermal vacuum of mixed states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hou%2C+X">Xu-Yang Hou</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zi-Wen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Z">Zheng Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+H">Hao Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Chien%2C+C">Chih-Chun Chien</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="2205.08679v2-abstract-short" style="display: inline;"> Two representations of mixed states by state-vectors, known as purified state and thermal vacuum, have been realized on quantum computers. While the two representations look similar, they differ by a partial transposition in the ancilla space. While ordinary observables cannot discern the two representations, we generalize the Berry phase of pure quantum states to mixed states and construct two ge… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.08679v2-abstract-full').style.display = 'inline'; document.getElementById('2205.08679v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2205.08679v2-abstract-full" style="display: none;"> Two representations of mixed states by state-vectors, known as purified state and thermal vacuum, have been realized on quantum computers. While the two representations look similar, they differ by a partial transposition in the ancilla space. While ordinary observables cannot discern the two representations, we generalize the Berry phase of pure quantum states to mixed states and construct two geometric phases that can reflect the partial transposition. By generalizing the adiabatic condition, we construct the thermal Berry phase, whose values from the two representations can be different, However, the thermal Berry phase may contain non-geometrical contributions. Alternatively, we generalize the parallel-transport condition to include the system and ancilla and show the dynamical phase is excluded under parallel transport. The geometrical phase accumulated in parallel transport is the generalized Berry phase, which may or may not differentiate a purified state from a thermal vacuum depending on the protocol. The generalizations of the Berry phase to mixed states may be realized and measured on quantum computers via the two representations to reveal the rich physics of finite-temperature quantum systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.08679v2-abstract-full').style.display = 'none'; document.getElementById('2205.08679v2-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> 25 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">15 pages, 1 figure</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Lett. A 457, 128553 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.09923">arXiv:2204.09923</a> <span> [<a href="https://arxiv.org/pdf/2204.09923">pdf</a>, <a href="https://arxiv.org/format/2204.09923">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link 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="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/10.1103/PhysRevLett.129.257001">10.1103/PhysRevLett.129.257001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Transport theory for topological Josephson junctions with a Majorana qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhi Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+J">Jia-Jin Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhao Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+Q">Qian Niu</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="2204.09923v1-abstract-short" style="display: inline;"> We construct a semiclassical theory for the transport of topological junctions starting from a microscopic Hamiltonian that comprehensively includes the interplay among the Majorana qubit, the Josephson phase, and the dissipation process. With the path integral approach, we derive a set of semiclassical equations of motion that can be used to calculate the time evolution of the Josephson phase and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.09923v1-abstract-full').style.display = 'inline'; document.getElementById('2204.09923v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.09923v1-abstract-full" style="display: none;"> We construct a semiclassical theory for the transport of topological junctions starting from a microscopic Hamiltonian that comprehensively includes the interplay among the Majorana qubit, the Josephson phase, and the dissipation process. With the path integral approach, we derive a set of semiclassical equations of motion that can be used to calculate the time evolution of the Josephson phase and the Majorana qubit. In the equations we reveal rich dynamical phenomena such as the qubit induced charge pumping, the effective spin-orbit torque, and the Gilbert damping. We demonstrate the influence of these dynamical phenomena on the transport signatures of the junction. We apply the theory to study the Shapiro steps of the junction, and find the suppression of the first Shapiro step due to the dynamical feedback of the Majorana qubit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.09923v1-abstract-full').style.display = 'none'; document.getElementById('2204.09923v1-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 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">6 pages, 3 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/2204.08605">arXiv:2204.08605</a> <span> [<a href="https://arxiv.org/pdf/2204.08605">pdf</a>, <a href="https://arxiv.org/format/2204.08605">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 - Experiment">hep-ex</span> </div> </div> <p class="title is-5 mathjax"> Quantum computing hardware for HEP algorithms and sensing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Alam%2C+M+S">M. Sohaib Alam</a>, <a href="/search/quant-ph?searchtype=author&query=Belomestnykh%2C+S">Sergey Belomestnykh</a>, <a href="/search/quant-ph?searchtype=author&query=Bornman%2C+N">Nicholas Bornman</a>, <a href="/search/quant-ph?searchtype=author&query=Cancelo%2C+G">Gustavo Cancelo</a>, <a href="/search/quant-ph?searchtype=author&query=Chao%2C+Y">Yu-Chiu Chao</a>, <a href="/search/quant-ph?searchtype=author&query=Checchin%2C+M">Mattia Checchin</a>, <a href="/search/quant-ph?searchtype=author&query=Dinh%2C+V+S">Vinh San Dinh</a>, <a href="/search/quant-ph?searchtype=author&query=Grassellino%2C+A">Anna Grassellino</a>, <a href="/search/quant-ph?searchtype=author&query=Gustafson%2C+E+J">Erik J. Gustafson</a>, <a href="/search/quant-ph?searchtype=author&query=Harnik%2C+R">Roni Harnik</a>, <a href="/search/quant-ph?searchtype=author&query=McRae%2C+C+R+H">Corey Rae Harrington McRae</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Ziwen Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Kapoor%2C+K">Keshav Kapoor</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+T">Taeyoon Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Kowalkowski%2C+J+B">James B. Kowalkowski</a>, <a href="/search/quant-ph?searchtype=author&query=Kramer%2C+M+J">Matthew J. Kramer</a>, <a href="/search/quant-ph?searchtype=author&query=Krasnikova%2C+Y">Yulia Krasnikova</a>, <a href="/search/quant-ph?searchtype=author&query=Kumar%2C+P">Prem Kumar</a>, <a href="/search/quant-ph?searchtype=author&query=Kurkcuoglu%2C+D+M">Doga Murat Kurkcuoglu</a>, <a href="/search/quant-ph?searchtype=author&query=Lamm%2C+H">Henry Lamm</a>, <a href="/search/quant-ph?searchtype=author&query=Lyon%2C+A+L">Adam L. Lyon</a>, <a href="/search/quant-ph?searchtype=author&query=Milathianaki%2C+D">Despina Milathianaki</a>, <a href="/search/quant-ph?searchtype=author&query=Murthy%2C+A">Akshay Murthy</a>, <a href="/search/quant-ph?searchtype=author&query=Mutus%2C+J">Josh Mutus</a>, <a href="/search/quant-ph?searchtype=author&query=Nekrashevich%2C+I">Ivan Nekrashevich</a> , et al. (15 additional authors not shown) </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="2204.08605v3-abstract-short" style="display: inline;"> Quantum information science harnesses the principles of quantum mechanics to realize computational algorithms with complexities vastly intractable by current computer platforms. Typical applications range from quantum chemistry to optimization problems and also include simulations for high energy physics. The recent maturing of quantum hardware has triggered preliminary explorations by several ins… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.08605v3-abstract-full').style.display = 'inline'; document.getElementById('2204.08605v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.08605v3-abstract-full" style="display: none;"> Quantum information science harnesses the principles of quantum mechanics to realize computational algorithms with complexities vastly intractable by current computer platforms. Typical applications range from quantum chemistry to optimization problems and also include simulations for high energy physics. The recent maturing of quantum hardware has triggered preliminary explorations by several institutions (including Fermilab) of quantum hardware capable of demonstrating quantum advantage in multiple domains, from quantum computing to communications, to sensing. The Superconducting Quantum Materials and Systems (SQMS) Center, led by Fermilab, is dedicated to providing breakthroughs in quantum computing and sensing, mediating quantum engineering and HEP based material science. The main goal of the Center is to deploy quantum systems with superior performance tailored to the algorithms used in high energy physics. In this Snowmass paper, we discuss the two most promising superconducting quantum architectures for HEP algorithms, i.e. three-level systems (qutrits) supported by transmon devices coupled to planar devices and multi-level systems (qudits with arbitrary N energy levels) supported by superconducting 3D cavities. For each architecture, we demonstrate exemplary HEP algorithms and identify the current challenges, ongoing work and future opportunities. Furthermore, we discuss the prospects and complexities of interconnecting the different architectures and individual computational nodes. Finally, we review several different strategies of error protection and correction and discuss their potential to improve the performance of the two architectures. This whitepaper seeks to reach out to the HEP community and drive progress in both HEP research and QIS hardware. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.08605v3-abstract-full').style.display = 'none'; document.getElementById('2204.08605v3-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 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 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">contribution to Snowmass 2021</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> FERMILAB-PUB-22-260-SQMS </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.06044">arXiv:2204.06044</a> <span> [<a href="https://arxiv.org/pdf/2204.06044">pdf</a>, <a href="https://arxiv.org/format/2204.06044">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="Instrumentation and Methods for Astrophysics">astro-ph.IM</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.129.210502">10.1103/PhysRevLett.129.210502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imaging stars with quantum error correction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zixin Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Brennen%2C+G+K">Gavin K. Brennen</a>, <a href="/search/quant-ph?searchtype=author&query=Ouyang%2C+Y">Yingkai Ouyang</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="2204.06044v2-abstract-short" style="display: inline;"> The development of high-resolution, large-baseline optical interferometers would revolutionize astronomical imaging. However, classical techniques are hindered by physical limitations including loss, noise, and the fact that the received light is generally quantum in nature. We show how to overcome these issues using quantum communication techniques. We present a general framework for using quantu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.06044v2-abstract-full').style.display = 'inline'; document.getElementById('2204.06044v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.06044v2-abstract-full" style="display: none;"> The development of high-resolution, large-baseline optical interferometers would revolutionize astronomical imaging. However, classical techniques are hindered by physical limitations including loss, noise, and the fact that the received light is generally quantum in nature. We show how to overcome these issues using quantum communication techniques. We present a general framework for using quantum error correction codes for protecting and imaging starlight received at distant telescope sites. In our scheme, the quantum state of light is coherently captured into a non-radiative atomic state via Stimulated Raman Adiabatic Passage, which is then imprinted into a quantum error correction code. The code protects the signal during subsequent potentially noisy operations necessary to extract the image parameters. We show that even a small quantum error correction code can offer significant protection against noise. For large codes, we find noise thresholds below which the information can be preserved. Our scheme represents an application for near-term quantum devices that can increase imaging resolution beyond what is feasible using classical techniques. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.06044v2-abstract-full').style.display = 'none'; document.getElementById('2204.06044v2-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> 25 May, 2023; <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">comments are welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.04378">arXiv:2204.04378</a> <span> [<a href="https://arxiv.org/pdf/2204.04378">pdf</a>, <a href="https://arxiv.org/format/2204.04378">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/PhysRevB.106.134313">10.1103/PhysRevB.106.134313 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Programmable Hamiltonian engineering with quadratic quantum Fourier transform </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+P">Pei Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Z">Zhijuan Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+X">Xingze Qiu</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="2204.04378v2-abstract-short" style="display: inline;"> Quantum Fourier transform (QFT) is a widely used building block for quantum algorithms, whose scalable implementation is challenging in experiments. Here, we propose a protocol of quadratic quantum Fourier transform (QQFT), considering cold atoms confined in an optical lattice. This QQFT is equivalent to QFT in the single-particle subspace, and produces a different unitary operation in the entire… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.04378v2-abstract-full').style.display = 'inline'; document.getElementById('2204.04378v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.04378v2-abstract-full" style="display: none;"> Quantum Fourier transform (QFT) is a widely used building block for quantum algorithms, whose scalable implementation is challenging in experiments. Here, we propose a protocol of quadratic quantum Fourier transform (QQFT), considering cold atoms confined in an optical lattice. This QQFT is equivalent to QFT in the single-particle subspace, and produces a different unitary operation in the entire Hilbert space. We show this QQFT protocol can be implemented using programmable laser potential with the digital-micromirror-device techniques recently developed in the experiments. The QQFT protocol enables programmable Hamiltonian engineering, and allows quantum simulations of Hamiltonian models, which are difficult to realize with conventional approaches. The flexibility of our approach is demonstrated by performing quantum simulations of one-dimensional Poincar茅 crystal physics and two-dimensional topological flat bands, where the QQFT protocol effectively generates the required long-range tunnelings despite the locality of the cold atom system. We find the discrete Poincar茅 symmetry and topological properties in the two examples respectively have robustness against a certain degree of noise that is potentially existent in the experimental realization. We expect this approach would open up wide opportunities for optical lattice based programmable quantum simulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.04378v2-abstract-full').style.display = 'none'; document.getElementById('2204.04378v2-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 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 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">11 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. B 106, 134313 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.01625">arXiv:2204.01625</a> <span> [<a href="https://arxiv.org/pdf/2204.01625">pdf</a>, <a href="https://arxiv.org/format/2204.01625">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Nuclear Experiment">nucl-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Theory">nucl-th</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/10.1126/sciadv.abq3903">10.1126/sciadv.abq3903 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tomography of Ultra-relativistic Nuclei with Polarized Photon-gluon Collisions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=STAR+Collaboration"> STAR Collaboration</a>, <a href="/search/quant-ph?searchtype=author&query=Abdallah%2C+M+S">M. S. Abdallah</a>, <a href="/search/quant-ph?searchtype=author&query=Aboona%2C+B+E">B. E. Aboona</a>, <a href="/search/quant-ph?searchtype=author&query=Adam%2C+J">J. Adam</a>, <a href="/search/quant-ph?searchtype=author&query=Adamczyk%2C+L">L. Adamczyk</a>, <a href="/search/quant-ph?searchtype=author&query=Adams%2C+J+R">J. R. Adams</a>, <a href="/search/quant-ph?searchtype=author&query=Adkins%2C+J+K">J. K. Adkins</a>, <a href="/search/quant-ph?searchtype=author&query=Agakishiev%2C+G">G. Agakishiev</a>, <a href="/search/quant-ph?searchtype=author&query=Aggarwal%2C+I">I. Aggarwal</a>, <a href="/search/quant-ph?searchtype=author&query=Aggarwal%2C+M+M">M. M. Aggarwal</a>, <a href="/search/quant-ph?searchtype=author&query=Ahammed%2C+Z">Z. Ahammed</a>, <a href="/search/quant-ph?searchtype=author&query=Aitbaev%2C+A">A. Aitbaev</a>, <a href="/search/quant-ph?searchtype=author&query=Alekseev%2C+I">I. Alekseev</a>, <a href="/search/quant-ph?searchtype=author&query=Anderson%2C+D+M">D. M. Anderson</a>, <a href="/search/quant-ph?searchtype=author&query=Aparin%2C+A">A. Aparin</a>, <a href="/search/quant-ph?searchtype=author&query=Aschenauer%2C+E+C">E. C. Aschenauer</a>, <a href="/search/quant-ph?searchtype=author&query=Ashraf%2C+M+U">M. U. Ashraf</a>, <a href="/search/quant-ph?searchtype=author&query=Atetalla%2C+F+G">F. G. Atetalla</a>, <a href="/search/quant-ph?searchtype=author&query=Averichev%2C+G+S">G. S. Averichev</a>, <a href="/search/quant-ph?searchtype=author&query=Bairathi%2C+V">V. Bairathi</a>, <a href="/search/quant-ph?searchtype=author&query=Baker%2C+W">W. Baker</a>, <a href="/search/quant-ph?searchtype=author&query=Cap%2C+J+G+B">J. G. Ball Cap</a>, <a href="/search/quant-ph?searchtype=author&query=Barish%2C+K">K. Barish</a>, <a href="/search/quant-ph?searchtype=author&query=Behera%2C+A">A. Behera</a>, <a href="/search/quant-ph?searchtype=author&query=Bellwied%2C+R">R. Bellwied</a> , et al. (370 additional authors not shown) </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="2204.01625v1-abstract-short" style="display: inline;"> A linearly polarized photon can be quantized from the Lorentz-boosted electromagnetic field of a nucleus traveling at ultra-relativistic speed. When two relativistic heavy nuclei pass one another at a distance of a few nuclear radii, the photon from one nucleus may interact through a virtual quark-antiquark pair with gluons from the other nucleus forming a short-lived vector meson (e.g. ${蟻^0}$).… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.01625v1-abstract-full').style.display = 'inline'; document.getElementById('2204.01625v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.01625v1-abstract-full" style="display: none;"> A linearly polarized photon can be quantized from the Lorentz-boosted electromagnetic field of a nucleus traveling at ultra-relativistic speed. When two relativistic heavy nuclei pass one another at a distance of a few nuclear radii, the photon from one nucleus may interact through a virtual quark-antiquark pair with gluons from the other nucleus forming a short-lived vector meson (e.g. ${蟻^0}$). In this experiment, the polarization was utilized in diffractive photoproduction to observe a unique spin interference pattern in the angular distribution of ${蟻^0\rightarrow蟺^+蟺^-}$ decays. The observed interference is a result of an overlap of two wave functions at a distance an order of magnitude larger than the ${蟻^0}$ travel distance within its lifetime. The strong-interaction nuclear radii were extracted from these diffractive interactions, and found to be $6.53\pm 0.06$ fm ($^{197} {\rm Au }$) and $7.29\pm 0.08$ fm ($^{238} {\rm U}$), larger than the nuclear charge radii. The observable is demonstrated to be sensitive to the nuclear geometry and quantum interference of non-identical particles. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.01625v1-abstract-full').style.display = 'none'; document.getElementById('2204.01625v1-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 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">Journal ref:</span> STAR Collaboration, Sci. Adv. 9, abq3903 (2023) </p> </li> </ol> <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=Huang%2C+Z&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Huang%2C+Z&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Huang%2C+Z&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Huang%2C+Z&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> </ul> </nav> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> </main> 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