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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=Feng%2C+X&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Feng%2C+X&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Feng%2C+X&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.01735">arXiv:2502.01735</a> <span> [<a href="https://arxiv.org/pdf/2502.01735">pdf</a>, <a href="https://arxiv.org/format/2502.01735">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> </div> <p class="title is-5 mathjax"> Postselection-free experimental observation of the measurement-induced phase transition in circuits with universal gates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaozhou Feng</a>, <a href="/search/quant-ph?searchtype=author&query=C%C3%B4t%C3%A9%2C+J">Jeremy C么t茅</a>, <a href="/search/quant-ph?searchtype=author&query=Kourtis%2C+S">Stefanos Kourtis</a>, <a href="/search/quant-ph?searchtype=author&query=Skinner%2C+B">Brian Skinner</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2502.01735v1-abstract-short" style="display: inline;"> Monitored many-body systems can exhibit a phase transition between entangling and disentangling dynamical phases by tuning the strength of measurements made on the system as it evolves. This phenomenon is called the measurement-induced phase transition (MIPT). Understanding the properties of the MIPT is a prominent challenge for both theory and experiment at the intersection of many-body physics a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.01735v1-abstract-full').style.display = 'inline'; document.getElementById('2502.01735v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.01735v1-abstract-full" style="display: none;"> Monitored many-body systems can exhibit a phase transition between entangling and disentangling dynamical phases by tuning the strength of measurements made on the system as it evolves. This phenomenon is called the measurement-induced phase transition (MIPT). Understanding the properties of the MIPT is a prominent challenge for both theory and experiment at the intersection of many-body physics and quantum information. Realizing the MIPT experimentally is particularly challenging due to the postselection problem, which demands a number of experimental realizations that grows exponentially with the number of measurements made during the dynamics. Proposed approaches that circumvent the postselection problem typically rely on a classical decoding process that infers the final state based on the measurement record. But the complexity of this classical process generally also grows exponentially with the system size unless the dynamics is restricted to a fine-tuned set of unitary operators. In this work we overcome these difficulties. We construct a tree-shaped quantum circuit whose nodes are Haar-random unitary operators followed by weak measurements of tunable strength. For these circuits, we show that the MIPT can be detected without postselection using only a simple classical decoding process whose complexity grows linearly with the number of qubits. Our protocol exploits the recursive structure of tree circuits, which also enables a complete theoretical description of the MIPT, including an exact solution for its critical point and scaling behavior. We experimentally realize the MIPT on Quantinuum's H1-1 trapped-ion quantum computer and show that the experimental results are precisely described by theory. Our results close the gap between analytical theory and postselection-free experimental observation of the MIPT. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.01735v1-abstract-full').style.display = 'none'; document.getElementById('2502.01735v1-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> 3 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">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/2412.10750">arXiv:2412.10750</a> <span> [<a href="https://arxiv.org/pdf/2412.10750">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"> Chip-to-chip photonic quantum teleportation over optical fibers of 12.3km </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+D">Dongning Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+Z">Zhanping Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jingyuan Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+X">Xiaotong Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+X">Xiaosong Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei 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="2412.10750v1-abstract-short" style="display: inline;"> Quantum teleportation is a crucial function in quantum networks. The implementation of photonic quantum teleportation could be highly simplified by quantum photonic circuits. To extend chip-to-chip teleportation distance, more effort is needed on both chip design and system implementation. In this work, we demonstrate a chip-to-chip photonic quantum teleportation over optical fibers under the scen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.10750v1-abstract-full').style.display = 'inline'; document.getElementById('2412.10750v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.10750v1-abstract-full" style="display: none;"> Quantum teleportation is a crucial function in quantum networks. The implementation of photonic quantum teleportation could be highly simplified by quantum photonic circuits. To extend chip-to-chip teleportation distance, more effort is needed on both chip design and system implementation. In this work, we demonstrate a chip-to-chip photonic quantum teleportation over optical fibers under the scenario of star-topology quantum network. Time-bin encoded quantum states are used to achieve a long teleportation distance. Three photonic quantum circuits are designed and fabricated on a single chip, each serving specific functions: heralded single-photon generation at the user node, entangled photon pair generation and Bell state measurement at the relay node, and projective measurement of the teleported photons at the central node. The unbalanced Mach-Zehnder interferometers (UMZI) for time-bin encoding in these quantum photonic circuits are optimized to reduce insertion losses and suppress noise photons generated on the chip. Besides, an active feedback system is employed to suppress the impact of fiber length fluctuation between the circuits, achieving a stable quantum interference for the Bell state measurement in the relay node. As the result, a photonic quantum teleportation over optical fibers of 12.3km is achieved based on these quantum photonic circuits, showing the potential of chip integration on the development of quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.10750v1-abstract-full').style.display = 'none'; document.getElementById('2412.10750v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.00786">arXiv:2412.00786</a> <span> [<a href="https://arxiv.org/pdf/2412.00786">pdf</a>, <a href="https://arxiv.org/ps/2412.00786">ps</a>, <a href="https://arxiv.org/format/2412.00786">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 Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Sensitively searching for microwave dark photons with atomic ensembles </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=He%2C+S">Suirong He</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+D">De He</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yufen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+L">Li Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xianing Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+H">Hao Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+L+F">L. F. Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2412.00786v1-abstract-short" style="display: inline;"> Dark photon is one of the promising candidates of light dark matter and could be detected by using its interaction with standard model particles via kinetic mixings. Here, we propose a feasible approach to detect the dark photons by nondestructively probing these mixing-induced quantum state transitions of atomic ensembles. Compared with the scheme by probing the mixing-induced quantum excitation… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.00786v1-abstract-full').style.display = 'inline'; document.getElementById('2412.00786v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.00786v1-abstract-full" style="display: none;"> Dark photon is one of the promising candidates of light dark matter and could be detected by using its interaction with standard model particles via kinetic mixings. Here, we propose a feasible approach to detect the dark photons by nondestructively probing these mixing-induced quantum state transitions of atomic ensembles. Compared with the scheme by probing the mixing-induced quantum excitation of single-atom detector, the achievable detection sensitivity can be enhanced theoretically by a factor of $\sqrt{N}$ for the ensemble containing $N$ atoms. Specifically, we show that the dark photons, in both centimeter- and millimeter-wave bands, could be detected by using the artificial atomic ensemble detector, generated by surface-state electrons on liquid Helium. It is estimated that, with the detectable transition probability of $10^{-4}$, the experimental surface-state electrons (with $N = 10^8$ trapped electrons) might provide a feasible approach to search for the dark photons in $18.61-26.88$ $渭$eV and $496.28-827.13$ $渭$eV ranges, within about two months. The confidence level can exceed 95\% for the achievable sensitivities being $10^{-14} \sim 10^{-13}$ and $10^{-12} \sim 10^{-11}$, respectively. In principle, the proposal could also be generalized to the other atomic ensemble detectors for the detection of dark photons in different frequency bands. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.00786v1-abstract-full').style.display = 'none'; document.getElementById('2412.00786v1-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 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.09367">arXiv:2410.09367</a> <span> [<a href="https://arxiv.org/pdf/2410.09367">pdf</a>, <a href="https://arxiv.org/format/2410.09367">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"> Wide-range quantum enhanced rotation sensing with 1+2 dimensional dynamical decoupling techniques </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X+N">X. N. Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+L+F">L. F. Wei</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="2410.09367v2-abstract-short" style="display: inline;"> We propose a motional dynamical decoupling technique by utilizing a sequence of $蟺$-phase shifts, instead of the conventional $蟺$-pulses for spin flipping, to implement the quantum enhanced rotation sensing with a 1+2 dimensional hybrid atomic Sagnic interferometor. By fully disentangling the spin from the two-dimensional vibrational modes of the particle under rotation, the spin coherence time an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.09367v2-abstract-full').style.display = 'inline'; document.getElementById('2410.09367v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.09367v2-abstract-full" style="display: none;"> We propose a motional dynamical decoupling technique by utilizing a sequence of $蟺$-phase shifts, instead of the conventional $蟺$-pulses for spin flipping, to implement the quantum enhanced rotation sensing with a 1+2 dimensional hybrid atomic Sagnic interferometor. By fully disentangling the spin from the two-dimensional vibrational modes of the particle under rotation, the spin coherence time and thus the phase accumulation can be significantly increased. Consequently, both the achievable sensitivity and dynamic range of the rotation sensing can be significantly enhanced and extended simultaneously, compared to the previous schemes where the spin and motions of the particle were not completely decoupled. The experimental feasibility for the unambiguous estimation of the rotation parameters is also discussed. Hopefully, this technique holds promise for overcoming certain challenges existing in the usual matter-wave Sagnac interferometers with trapped particles, particularly for the practical inertial navigation that demands both high sensitivity and large dynamic range. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.09367v2-abstract-full').style.display = 'none'; document.getElementById('2410.09367v2-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.02758">arXiv:2410.02758</a> <span> [<a href="https://arxiv.org/pdf/2410.02758">pdf</a>, <a href="https://arxiv.org/format/2410.02758">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> </div> </div> <p class="title is-5 mathjax"> Pseudoentanglement from tensor networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+Z">Zihan Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaozhou Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Ippoliti%2C+M">Matteo Ippoliti</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="2410.02758v2-abstract-short" style="display: inline;"> Pseudoentangled states are defined by their ability to hide their entanglement structure: they are indistinguishable from random states to any observer with polynomial resources, yet can have much less entanglement than random states. Existing constructions of pseudoentanglement based on phase- and/or subset-states are limited in the entanglement structures they can hide: e.g., the states may have… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.02758v2-abstract-full').style.display = 'inline'; document.getElementById('2410.02758v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.02758v2-abstract-full" style="display: none;"> Pseudoentangled states are defined by their ability to hide their entanglement structure: they are indistinguishable from random states to any observer with polynomial resources, yet can have much less entanglement than random states. Existing constructions of pseudoentanglement based on phase- and/or subset-states are limited in the entanglement structures they can hide: e.g., the states may have low entanglement on a single cut, on all cuts at once, or on local cuts in one dimension. Here we introduce new constructions of pseudoentangled states based on (pseudo)random tensor networks that affords much more flexibility in the achievable entanglement structures. We illustrate our construction with the simplest example of a matrix product state, realizable as a staircase circuit of pseudorandom unitary gates, which exhibits pseudo-area-law scaling of entanglement in one dimension. We then generalize our construction to arbitrary tensor network structures that admit an isometric realization. A notable application of this result is the construction of pseudoentangled `holographic' states whose entanglement entropy obeys a Ryu-Takayanagi `minimum-cut' formula, answering a question posed in [Aaronson et al., arXiv:2211.00747]. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.02758v2-abstract-full').style.display = 'none'; document.getElementById('2410.02758v2-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 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">5+6 pages, 3 figures. v2: fixed typos and minor issues</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.10045">arXiv:2408.10045</a> <span> [<a href="https://arxiv.org/pdf/2408.10045">pdf</a>, <a href="https://arxiv.org/format/2408.10045">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="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"> Gapless spin excitations in nanographene-based antiferromagnetic spin-1/2 Heisenberg chains </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+C">Chenxiao Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+L">Lin Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Henriques%2C+J+C+G">Jo茫o C. G. Henriques</a>, <a href="/search/quant-ph?searchtype=author&query=Ferri-Cort%C3%A9s%2C+M">Mar Ferri-Cort茅s</a>, <a href="/search/quant-ph?searchtype=author&query=Catarina%2C+G">Gon莽alo Catarina</a>, <a href="/search/quant-ph?searchtype=author&query=Pignedoli%2C+C+A">Carlo A. Pignedoli</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+J">Ji Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xinliang Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Ruffieux%2C+P">Pascal Ruffieux</a>, <a href="/search/quant-ph?searchtype=author&query=Fern%C3%A1ndez-Rossier%2C+J">Joaqu铆n Fern谩ndez-Rossier</a>, <a href="/search/quant-ph?searchtype=author&query=Fasel%2C+R">Roman Fasel</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="2408.10045v1-abstract-short" style="display: inline;"> Haldane's seminal work established two fundamentally different types of excitation spectra for antiferromagnetic Heisenberg quantum spin chains: gapped excitations in integer-spin chains and gapless excitations in half-integer-spin chains. In finite-length half-integer spin chains, quantization, however, induces a gap in the excitation spectrum, with the upper bound given by the Lieb-Schulz-Mattis… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.10045v1-abstract-full').style.display = 'inline'; document.getElementById('2408.10045v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.10045v1-abstract-full" style="display: none;"> Haldane's seminal work established two fundamentally different types of excitation spectra for antiferromagnetic Heisenberg quantum spin chains: gapped excitations in integer-spin chains and gapless excitations in half-integer-spin chains. In finite-length half-integer spin chains, quantization, however, induces a gap in the excitation spectrum, with the upper bound given by the Lieb-Schulz-Mattis (LSM) theorem. Here, we investigate the length-dependent excitations in spin-1/2 Heisenberg chains obtained by covalently linking olympicenes--Olympic rings shaped nanographenes carrying spin-1/2--into one-dimensional chains. The large exchange interaction (J~38 mV) between olympicenes and the negligible magnetic anisotropy in these nanographenes make them an ideal platform for studying quantum spin excitations, which we directly measure using inelastic electron tunneling spectroscopy. We observe a power-law decay of the lowest excitation energy with increasing chain length L, remaining below the LSM boundary. In a long chain with L = 50, a nearly V-shaped excitation continuum is observed, reinforcing the system's gapless nature in the thermodynamic limit. Finally, we visualize the standing wave of a single spinon confined in odd-numbered chains using low-bias current maps. Our results provide compelling evidence for the realization of a one-dimensional analog of a gapless spin liquid. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.10045v1-abstract-full').style.display = 'none'; document.getElementById('2408.10045v1-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 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">5 figures. arXiv admin note: text overlap with arXiv:2402.13590</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.09083">arXiv:2408.09083</a> <span> [<a href="https://arxiv.org/pdf/2408.09083">pdf</a>, <a href="https://arxiv.org/format/2408.09083">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"> Imaginary Hamiltonian variational ansatz for combinatorial optimization problems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiaoyang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Chai%2C+Y">Yahui Chai</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xu Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yibin Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Jansen%2C+K">Karl Jansen</a>, <a href="/search/quant-ph?searchtype=author&query=T%C3%BCys%C3%BCz%2C+C">Cenk T眉ys眉z</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="2408.09083v2-abstract-short" style="display: inline;"> Obtaining exact solutions to combinatorial optimization problems using classical computing is computationally expensive. The current tenet in the field is that quantum computers can address these problems more efficiently. While promising algorithms require fault-tolerant quantum hardware, variational algorithms have emerged as viable candidates for near-term devices. The success of these algorith… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.09083v2-abstract-full').style.display = 'inline'; document.getElementById('2408.09083v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.09083v2-abstract-full" style="display: none;"> Obtaining exact solutions to combinatorial optimization problems using classical computing is computationally expensive. The current tenet in the field is that quantum computers can address these problems more efficiently. While promising algorithms require fault-tolerant quantum hardware, variational algorithms have emerged as viable candidates for near-term devices. The success of these algorithms hinges on multiple factors, with the design of the ansatz having the utmost importance. It is known that popular approaches such as quantum approximate optimization algorithm (QAOA) and quantum annealing suffer from adiabatic bottlenecks, that lead to either larger circuit depth or evolution time. On the other hand, the evolution time of imaginary time evolution is bounded by the inverse energy gap of the Hamiltonian, which is constant for most non-critical physical systems. In this work, we propose imaginary Hamiltonian variational ansatz ($i$HVA) inspired by quantum imaginary time evolution to solve the MaxCut problem. We introduce a tree arrangement of the parametrized quantum gates, enabling the exact solution of arbitrary tree graphs using the one-round $i$HVA. For randomly generated $D$-regular graphs, we numerically demonstrate that the $i$HVA solves the MaxCut problem with a small constant number of rounds and sublinear depth, outperforming QAOA, which requires rounds increasing with the graph size. Furthermore, our ansatz solves MaxCut exactly for graphs with up to 24 nodes and $D \leq 5$, whereas only approximate solutions can be derived by the classical near-optimal Goemans-Williamson algorithm. We validate our simulated results with hardware demonstrations on a graph with 67 nodes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.09083v2-abstract-full').style.display = 'none'; document.getElementById('2408.09083v2-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 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 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">24 pages, 17 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> RIKEN-iTHEMS-Report-25 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.20511">arXiv:2407.20511</a> <span> [<a href="https://arxiv.org/pdf/2407.20511">pdf</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="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</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="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Building spin-1/2 antiferromagnetic Heisenberg chains with diaza-nanographenes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Fu%2C+X">Xiaoshuai Fu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+L">Li Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+K">Kun Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Henriques%2C+J+C+G">Jo茫o C. G. Henriques</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+Y">Yixuan Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+X">Xianghe Han</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Hui Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Palma%2C+C">Carlos-Andres Palma</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+Z">Zhihai Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+X">Xiao Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+S">Shixuan Du</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+J">Ji Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Fern%C3%A1ndez-Rossier%2C+J">Joaqu铆n Fern谩ndez-Rossier</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xinliang Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+H">Hong-Jun Gao</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="2407.20511v1-abstract-short" style="display: inline;"> Understanding and engineering the coupling of spins in nanomaterials is of central importance for designing novel devices. Graphene nanostructures with 蟺-magnetism offer a chemically tunable platform to explore quantum magnetic interactions. However, realizing spin chains bearing controlled odd-even effects with suitable nanographene systems is challenging. Here, we demonstrate the successful on-s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.20511v1-abstract-full').style.display = 'inline'; document.getElementById('2407.20511v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.20511v1-abstract-full" style="display: none;"> Understanding and engineering the coupling of spins in nanomaterials is of central importance for designing novel devices. Graphene nanostructures with 蟺-magnetism offer a chemically tunable platform to explore quantum magnetic interactions. However, realizing spin chains bearing controlled odd-even effects with suitable nanographene systems is challenging. Here, we demonstrate the successful on-surface synthesis of spin-1/2 antiferromagnetic Heisenberg chains with parity-dependent magnetization based on antiaromatic diaza-hexa-peri-hexabenzocoronene (diaza-HBC) units. Using distinct synthetic strategies, two types of spin chains with different terminals were synthesized, both exhibiting a robust odd-even effect on the spin coupling along the chain. Combined investigations using scanning tunneling microscopy, non-contact atomic force microscopy, density functional theory calculations, and quantum spin models confirmed the structures of the diaza-HBC chains and revealed their magnetic properties, which has an S = 1/2 spin per unit through electron donation from the diaza-HBC core to the Au(111) substrate. Gapped excitations were observed in even-numbered chains, while enhanced Kondo resonance emerged in odd-numbered units of odd-numbered chains due to the redistribution of the unpaired spin along the chain. Our findings provide an effective strategy to construct nanographene spin chains and unveil the odd-even effect in their magnetic properties, offering potential applications in nanoscale spintronics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.20511v1-abstract-full').style.display = 'none'; document.getElementById('2407.20511v1-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.08398">arXiv:2407.08398</a> <span> [<a href="https://arxiv.org/pdf/2407.08398">pdf</a>, <a href="https://arxiv.org/format/2407.08398">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/PhysRevB.110.144305">10.1103/PhysRevB.110.144305 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Delocalization of skin steady states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xu Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Shu 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="2407.08398v1-abstract-short" style="display: inline;"> The skin effect, characterized by the tendency of particles to accumulate at the boundaries, has been extensively studied in non-Hermitian systems. In this work, we propose an intuitive Lindbladian composed of two chains with reversed skin localization. The skin steady state is gradually delocalized as the interchain coupling increases. In the single-body scenario, it corresponds to a shift in the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.08398v1-abstract-full').style.display = 'inline'; document.getElementById('2407.08398v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.08398v1-abstract-full" style="display: none;"> The skin effect, characterized by the tendency of particles to accumulate at the boundaries, has been extensively studied in non-Hermitian systems. In this work, we propose an intuitive Lindbladian composed of two chains with reversed skin localization. The skin steady state is gradually delocalized as the interchain coupling increases. In the single-body scenario, it corresponds to a shift in the scaling of the Liouvillian gap $螖$ from $螖\propto N^0$ to $螖\propto N^{-2}$. Notably, exact diagonalization results reveal a system-size sensitivity of the single-particle Liouvillian spectrum, inherited from the non-Hermitian effective Hamiltonian's system-size sensitivity. We predict that even an arbitrarily small coupling will induce dramatic changes in the Liouvillian spectrum and steady state in the thermodynamic limit, a phenomenon we term the critical Liouvillian skin effect. Additionally, in the many-body scenario, by employing the stochastic Schr枚dinger equation to unravel the Lindblad master equation, it is revealed that the scaling behavior of steady-state entanglement changes from the area law to the logarithmic law. This work demonstrates the delocalization of both single-body and many-body skin steady states, introducing a novel mechanism for inducing entanglement transitions beyond the quantum Zeno effect. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.08398v1-abstract-full').style.display = 'none'; document.getElementById('2407.08398v1-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 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">10 pages,7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 110, 144305 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.11788">arXiv:2406.11788</a> <span> [<a href="https://arxiv.org/pdf/2406.11788">pdf</a>, <a href="https://arxiv.org/format/2406.11788">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> </div> <p class="title is-5 mathjax"> Holographic Classical Shadow Tomography </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuhan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaozhou Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Ippoliti%2C+M">Matteo Ippoliti</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+Y">Yi-Zhuang You</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="2406.11788v1-abstract-short" style="display: inline;"> We introduce "holographic shadows", a new class of randomized measurement schemes for classical shadow tomography that achieves the optimal scaling of sample complexity for learning geometrically local Pauli operators at any length scale, without the need for fine-tuning protocol parameters such as circuit depth or measurement rate. Our approach utilizes hierarchical quantum circuits, such as tree… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.11788v1-abstract-full').style.display = 'inline'; document.getElementById('2406.11788v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.11788v1-abstract-full" style="display: none;"> We introduce "holographic shadows", a new class of randomized measurement schemes for classical shadow tomography that achieves the optimal scaling of sample complexity for learning geometrically local Pauli operators at any length scale, without the need for fine-tuning protocol parameters such as circuit depth or measurement rate. Our approach utilizes hierarchical quantum circuits, such as tree quantum circuits or holographic random tensor networks. Measurements within the holographic bulk correspond to measurements at different scales on the boundary (i.e. the physical system of interests), facilitating efficient quantum state estimation across observable at all scales. Considering the task of estimating string-like Pauli observables supported on contiguous intervals of $k$ sites in a 1D system, our method achieves an optimal sample complexity scaling of $\sim d^k\mathrm{poly}(k)$, with $d$ the local Hilbert space dimension. We present a holographic minimal cut framework to demonstrate the universality of this sample complexity scaling and validate it with numerical simulations, illustrating the efficacy of holographic shadows in enhancing quantum state learning capabilities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.11788v1-abstract-full').style.display = 'none'; document.getElementById('2406.11788v1-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 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">20 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.13894">arXiv:2405.13894</a> <span> [<a href="https://arxiv.org/pdf/2405.13894">pdf</a>, <a href="https://arxiv.org/format/2405.13894">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"> Charge and Spin Sharpening Transitions on Dynamical Quantum Trees </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaozhou Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Fishchenko%2C+N">Nadezhda Fishchenko</a>, <a href="/search/quant-ph?searchtype=author&query=Gopalakrishnan%2C+S">Sarang Gopalakrishnan</a>, <a href="/search/quant-ph?searchtype=author&query=Ippoliti%2C+M">Matteo Ippoliti</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.13894v1-abstract-short" style="display: inline;"> The dynamics of monitored systems can exhibit a measurement-induced phase transition (MIPT) between entangling and disentangling phases, tuned by the measurement rate. When the dynamics obeys a continuous symmetry, the entangling phase further splits into a fuzzy phase and a sharp phase based on the scaling of fluctuations of the symmetry charge. While the sharpening transition for Abelian symmetr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.13894v1-abstract-full').style.display = 'inline'; document.getElementById('2405.13894v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.13894v1-abstract-full" style="display: none;"> The dynamics of monitored systems can exhibit a measurement-induced phase transition (MIPT) between entangling and disentangling phases, tuned by the measurement rate. When the dynamics obeys a continuous symmetry, the entangling phase further splits into a fuzzy phase and a sharp phase based on the scaling of fluctuations of the symmetry charge. While the sharpening transition for Abelian symmetries is well understood analytically, no such understanding exists for the non- Abelian case. In this work, building on a recent analytical solution of the MIPT on tree-like circuit architectures (where qubits are repatedly added or removed from the system in a recursive pattern), we study entanglement and sharpening transitions in monitored dynamical quantum trees obeying U (1) and SU (2) symmetries. The recursive structure of tree tensor networks enables powerful analytical and numerical methods to determine the phase diagrams in both cases. In the U (1) case, we analytically derive a Fisher-KPP-like differential equation that allows us to locate the critical point and identify its properties. We find that the entanglement/purification and sharpening transitions generically occur at distinct measurement rates. In the SU (2) case, we find that the fuzzy phase is generic, and a sharp phase is possible only in the limit of maximal measurement rate. In this limit, we analytically solve the boundaries separating the fuzzy and sharp phases, and find them to be in agreement with exact numerical simulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.13894v1-abstract-full').style.display = 'none'; document.getElementById('2405.13894v1-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">originally announced</span> 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/2405.04090">arXiv:2405.04090</a> <span> [<a href="https://arxiv.org/pdf/2405.04090">pdf</a>, <a href="https://arxiv.org/ps/2405.04090">ps</a>, <a href="https://arxiv.org/format/2405.04090">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"> Protecting quantum gates from arbitrary single- and two-qubit errors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+C">Chunfeng Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+G">Gangcheng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xun-Li Feng</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.04090v1-abstract-short" style="display: inline;"> We explore the protection of quantum gates from arbitrary single- and two-qubit noises with properly designed dynamical decoupling pulses. The proposed dynamical decoupling method is a concatenation of a sequence of pulses formed by $蟽_x$, $蟽_x蟽_x$ with another sequence constructed by $蟽_z$, $蟽_z蟽_z$. The concatenation of the two sequences results in desired pulses to fight agianst any single- and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.04090v1-abstract-full').style.display = 'inline'; document.getElementById('2405.04090v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.04090v1-abstract-full" style="display: none;"> We explore the protection of quantum gates from arbitrary single- and two-qubit noises with properly designed dynamical decoupling pulses. The proposed dynamical decoupling method is a concatenation of a sequence of pulses formed by $蟽_x$, $蟽_x蟽_x$ with another sequence constructed by $蟽_z$, $蟽_z蟽_z$. The concatenation of the two sequences results in desired pulses to fight agianst any single- and two-qubit errors. The success of our method relies on the ability to adjust system parameters or interaction terms, which can be achieved in different physical systems, including trapped ions and superconducting qubits. We finally explore the performance of our method numerically with the above-mentioned errors that are changing at any moment and show the preferred protection offered by the method. Therefore, our method is a timely step forward in preserving quantum gates at the level of physical qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.04090v1-abstract-full').style.display = 'none'; document.getElementById('2405.04090v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 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/2403.09619">arXiv:2403.09619</a> <span> [<a href="https://arxiv.org/pdf/2403.09619">pdf</a>, <a href="https://arxiv.org/format/2403.09619">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> </div> <p class="title is-5 mathjax"> Dynamics of Pseudoentanglement </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaozhou Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Ippoliti%2C+M">Matteo Ippoliti</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="2403.09619v2-abstract-short" style="display: inline;"> The dynamics of quantum entanglement plays a central role in explaining the emergence of thermal equilibrium in isolated many-body systems. However, entanglement is notoriously hard to measure: recent works have introduced a notion of pseudoentanglement describing ensembles of many-body states that, while only weakly entangled, cannot be efficiently distinguished from states with much higher entan… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.09619v2-abstract-full').style.display = 'inline'; document.getElementById('2403.09619v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.09619v2-abstract-full" style="display: none;"> The dynamics of quantum entanglement plays a central role in explaining the emergence of thermal equilibrium in isolated many-body systems. However, entanglement is notoriously hard to measure: recent works have introduced a notion of pseudoentanglement describing ensembles of many-body states that, while only weakly entangled, cannot be efficiently distinguished from states with much higher entanglement. This prompts the question: how much entanglement is truly necessary to achieve thermal equilibrium in quantum systems? In this work we address this question by introducing random circuit models of quantum dynamics that, at late times, equilibrate to pseudoentangled ensembles -- a phenomenon we name pseudothermalization. These models replicate all the efficiently observable predictions of thermal equilibrium, while generating only a small amount of entanglement, thus deviating from the "maximum-entropy principle" that underpins thermodynamics. We examine (i) how a pseudoentangled ensemble on a small subsystem spreads to the whole system as a function of time, and (ii) how a pseudoentangled ensemble can be generated from an initial product state. We map the above problems onto a family of classical Markov chains on subsets of the computational basis. The mixing times of such Markov chains are related to the time scales at which the states produced from the dynamics become indistinguishable from Haar-random states at the level of each statistical moment. Based on a combination of rigorous bounds and conjectures supported by numerics, we argue that each Markov chain's relaxation time and mixing time have different asymptotic behavior in the limit of large system size. This is a necessary condition for a cutoff phenomenon: an abrupt dynamical transition to equilibrium. We thus conjecture that our random circuits give rise to asymptotically sharp pseudothermalization transitions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.09619v2-abstract-full').style.display = 'none'; document.getElementById('2403.09619v2-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, 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">16 pages main text + 8 pages appendix. 9 figures. v2: thoroughly updated presentation, added subsection VI.B on 'Implications', added note on recent results on spectral gaps of random circuits</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.13590">arXiv:2402.13590</a> <span> [<a href="https://arxiv.org/pdf/2402.13590">pdf</a>, <a href="https://arxiv.org/format/2402.13590">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="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</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="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Tunable topological phases in nanographene-based spin-1/2 alternating-exchange Heisenberg chains </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+C">Chenxiao Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Catarina%2C+G">Gon莽alo Catarina</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jin-Jiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Henriques%2C+J+C+G">Jo茫o C. G. Henriques</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+L">Lin Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+J">Ji Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xinliang Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Gr%C3%B6ning%2C+O">Oliver Gr枚ning</a>, <a href="/search/quant-ph?searchtype=author&query=Ruffieux%2C+P">Pascal Ruffieux</a>, <a href="/search/quant-ph?searchtype=author&query=Fern%C3%A1ndez-Rossier%2C+J">Joaqu铆n Fern谩ndez-Rossier</a>, <a href="/search/quant-ph?searchtype=author&query=Fasel%2C+R">Roman Fasel</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="2402.13590v1-abstract-short" style="display: inline;"> Unlocking the potential of topological order within many-body spin systems has long been a central pursuit in the realm of quantum materials. Despite extensive efforts, the quest for a versatile platform enabling site-selective spin manipulation, essential for tuning and probing diverse topological phases, has persisted. Here, we utilize on-surface synthesis to construct spin-1/2 alternating-excha… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.13590v1-abstract-full').style.display = 'inline'; document.getElementById('2402.13590v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.13590v1-abstract-full" style="display: none;"> Unlocking the potential of topological order within many-body spin systems has long been a central pursuit in the realm of quantum materials. Despite extensive efforts, the quest for a versatile platform enabling site-selective spin manipulation, essential for tuning and probing diverse topological phases, has persisted. Here, we utilize on-surface synthesis to construct spin-1/2 alternating-exchange Heisenberg (AH) chains[1] with antiferromagnetic couplings $J_1$ and $J_2$ by covalently linking Clar's goblets -- nanographenes each hosting two antiferromagnetically-coupled unpaired electrons[2]. Utilizing scanning tunneling microscopy, we exert atomic-scale control over the spin chain lengths, parities and exchange-coupling terminations, and probe their magnetic response by means of inelastic tunneling spectroscopy. Our investigation confirms the gapped nature of bulk excitations in the chains, known as triplons[3]. Besides, the triplon dispersion relation is successfully extracted from the spatial variation of tunneling spectral amplitudes. Furthermore, depending on the parity and termination of chains, we observe varying numbers of in-gap $S=1/2$ edge spins, enabling the determination of the degeneracy of distinct topological ground states in the thermodynamic limit-either 1, 2, or 4. By monitoring interactions between these edge spins, we identify the exponential decay of spin correlations. Our experimental findings, corroborated by theoretical calculations, present a phase-controlled many-body platform, opening promising avenues toward the development of spin-based quantum devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.13590v1-abstract-full').style.display = 'none'; document.getElementById('2402.13590v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.10697">arXiv:2401.10697</a> <span> [<a href="https://arxiv.org/pdf/2401.10697">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"> Reconfigurable entanglement distribution network based on pump management of spontaneous four-wave mixing source </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jingyuan Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+D">Dongning Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+Z">Zhanping Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+Z">Zhihao Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei 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="2401.10697v1-abstract-short" style="display: inline;"> Leveraging the unique properties of quantum entanglement, quantum entanglement distribution networks support multiple quantum information applications and are essential to the development of quantum networks. However, its practical implementation poses significant challenges to network scalability and flexibility. In this work, we propose a novel reconfigurable entanglement distribution network ba… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.10697v1-abstract-full').style.display = 'inline'; document.getElementById('2401.10697v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.10697v1-abstract-full" style="display: none;"> Leveraging the unique properties of quantum entanglement, quantum entanglement distribution networks support multiple quantum information applications and are essential to the development of quantum networks. However, its practical implementation poses significant challenges to network scalability and flexibility. In this work, we propose a novel reconfigurable entanglement distribution network based on tunable multi-pump excitation of a spontaneous four-wave mixing (SFWM) source and a time-sharing method. We characterize the two-photon correlation under different pump conditions to demonstrate the effect of pump degenerate and pump non-degenerate SFWM processes on the two-photon correlation, and its tunability. Then as a benchmark application, a 10-user fully-connected quantum key distribution (QKD) network is established in a time-sharing way with triple pump lights. Each user receives one frequency channel thus it shows a linear scaling between the number of frequency channels and the user number in despite of the network topology. Our results thus provide a promising networking scheme for large-scale entanglement distribution networks owing to its scalability, functionality, and reconfigurability. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.10697v1-abstract-full').style.display = 'none'; document.getElementById('2401.10697v1-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">15 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/2312.05732">arXiv:2312.05732</a> <span> [<a href="https://arxiv.org/pdf/2312.05732">pdf</a>, <a href="https://arxiv.org/ps/2312.05732">ps</a>, <a href="https://arxiv.org/format/2312.05732">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"> Reply to "Comment on `Generalized James' effective Hamiltonian method'" </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Shao%2C+W">Wenjun Shao</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+C">Chunfeng Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xun-Li Feng</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="2312.05732v3-abstract-short" style="display: inline;"> In the preceding Comment [1] it was claimed that the third-order Hamiltonian obtained in our original paper [2] is not Hermitian for general situations when considering time-dependence and the way of deriving the effective third-order expansion is not very rigorous. To reply the comment we should emphasize the following three points: first of all, the third-order Hamiltonian given in our paper is… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.05732v3-abstract-full').style.display = 'inline'; document.getElementById('2312.05732v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.05732v3-abstract-full" style="display: none;"> In the preceding Comment [1] it was claimed that the third-order Hamiltonian obtained in our original paper [2] is not Hermitian for general situations when considering time-dependence and the way of deriving the effective third-order expansion is not very rigorous. To reply the comment we should emphasize the following three points: first of all, the third-order Hamiltonian given in our paper is exactly Hermitian under the conditions mentioned there. Secondly, the iterative method adopted in our paper to derive the generalized effective Hamiltonian is equivalent to the Dyson series, and its correctness can thus be guaranteed. Thirdly, although the truncated effective Hamiltonian is indeed non-Hermitian under the time-dependent situation as presented in the Comment, it corresponds exactly to the non-unitary truncated Dyson series. Considering the truncated Dyson series has been extensively utilized in the time-dependent perturbation theory, in our opinion, the non-Hermitian truncated effective Hamiltonian can still be treated as an approximation of the effective Hamiltonian. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.05732v3-abstract-full').style.display = 'none'; document.getElementById('2312.05732v3-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 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 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> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.17489">arXiv:2311.17489</a> <span> [<a href="https://arxiv.org/pdf/2311.17489">pdf</a>, <a href="https://arxiv.org/format/2311.17489">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/PhysRevB.109.014313">10.1103/PhysRevB.109.014313 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Boundary sensitive Lindbladians and relaxation dynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xu Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Shu 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="2311.17489v1-abstract-short" style="display: inline;"> It is well known that non-Hermitian systems can be extremely sensitive to boundary conditions owing to non-Hermitian skin effect (NHSE). Analogously, we investigate two boundary-sensitive $U(1)$ symmetric Lindbladians: one carries current in the steady state, and the other does not. The numerical results indicate significant change of the Liouvillian spectrum, eigenmodes and relaxation time for bo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.17489v1-abstract-full').style.display = 'inline'; document.getElementById('2311.17489v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.17489v1-abstract-full" style="display: none;"> It is well known that non-Hermitian systems can be extremely sensitive to boundary conditions owing to non-Hermitian skin effect (NHSE). Analogously, we investigate two boundary-sensitive $U(1)$ symmetric Lindbladians: one carries current in the steady state, and the other does not. The numerical results indicate significant change of the Liouvillian spectrum, eigenmodes and relaxation time for both Lindbladians when the boundary conditions are altered. This phenomenon is found to be triggered by the Liouvillian skin effect (LSE), specifically the localization of eigenmodes, which stems from the NHSE of the non-Hermitian effective Hamiltonian. In addition, these two Lindbladians manifest different LSE, ultimately resulting in distinct relaxation behaviors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.17489v1-abstract-full').style.display = 'none'; document.getElementById('2311.17489v1-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 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">19pages, 27 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 109, 014313 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.04895">arXiv:2309.04895</a> <span> [<a href="https://arxiv.org/pdf/2309.04895">pdf</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="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Super-compact universal quantum logic gates with inversedesigned elements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=He%2C+L">Lu He</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+D">Dongning Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+J">Jingxing Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weixuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+H">Huizhen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xiangdong 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="2309.04895v1-abstract-short" style="display: inline;"> Integrated quantum photonic circuit is a promising platform for the realization of quantum information processing in the future. To achieve the largescale quantum photonic circuits, the applied quantum logic gates should be as small as possible for the high-density integration on chips. Here, we report the implementation of super-compact universal quantum logic gates on silicon chips by the method… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.04895v1-abstract-full').style.display = 'inline'; document.getElementById('2309.04895v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.04895v1-abstract-full" style="display: none;"> Integrated quantum photonic circuit is a promising platform for the realization of quantum information processing in the future. To achieve the largescale quantum photonic circuits, the applied quantum logic gates should be as small as possible for the high-density integration on chips. Here, we report the implementation of super-compact universal quantum logic gates on silicon chips by the method of inverse design. In particular, the fabricated controlled-NOT gate and Hadamard gate are both nearly a vacuum wavelength, being the smallest optical quantum gates reported up to now. We further design the quantum circuit by cascading these fundamental gates to perform arbitrary quantum processing, where the corresponding size is about several orders smaller than that of previous quantum photonic circuits. Our study paves the way for the realization of largescale quantum photonic chips with integrated sources, and can possess important applications in the field of quantum information processes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.04895v1-abstract-full').style.display = 'none'; document.getElementById('2309.04895v1-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> 9 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">Journal ref:</span> Sci. Adv.9,eadg6685(2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.04136">arXiv:2308.04136</a> <span> [<a href="https://arxiv.org/pdf/2308.04136">pdf</a>, <a href="https://arxiv.org/format/2308.04136">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"> Sub-SQL electronic field sensing by simultaneously using quantum entanglements and squeezings </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X+N">X. N. Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+M">M. Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+L+F">L. F. Wei</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="2308.04136v4-abstract-short" style="display: inline;"> Quantum entanglement and quantum squeezing are two most typical approaches to beat the standard quantum limit (SQL) of the sensitive phase estimations in quantum metrology. Each of them has already been utilized individually to improve the sensitivity of electric field sensing with the trapped ion platform, but the upper bound of the demonstrated sensitivity gain is very limited, i.e., the experim… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.04136v4-abstract-full').style.display = 'inline'; document.getElementById('2308.04136v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.04136v4-abstract-full" style="display: none;"> Quantum entanglement and quantum squeezing are two most typical approaches to beat the standard quantum limit (SQL) of the sensitive phase estimations in quantum metrology. Each of them has already been utilized individually to improve the sensitivity of electric field sensing with the trapped ion platform, but the upper bound of the demonstrated sensitivity gain is very limited, i.e., the experimental 3dB and theoretical 6dB, over the SQL. Here, by simultaneously using the internal (spin)-external (oscillator) state entanglements and the oscillator squeezings to effectively amplify the accumulation phase, we show that these sensitivity gains can be effectively surpassed. Hopefully, the proposal provides a novel approach to the stronger beaten of the SQL for the sensitive sensings of the desired electric field and also the other metrologies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.04136v4-abstract-full').style.display = 'none'; document.getElementById('2308.04136v4-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.13598">arXiv:2307.13598</a> <span> [<a href="https://arxiv.org/pdf/2307.13598">pdf</a>, <a href="https://arxiv.org/format/2307.13598">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> </div> </div> <p class="title is-5 mathjax"> Symmetry enhanced variational quantum imaginary time evolution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiaoyang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Chai%2C+Y">Yahui Chai</a>, <a href="/search/quant-ph?searchtype=author&query=Demidik%2C+M">Maria Demidik</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xu Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Jansen%2C+K">Karl Jansen</a>, <a href="/search/quant-ph?searchtype=author&query=T%C3%BCys%C3%BCz%2C+C">Cenk T眉ys眉z</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="2307.13598v1-abstract-short" style="display: inline;"> The variational quantum imaginary time evolution (VarQITE) algorithm is a near-term method to prepare the ground state and Gibbs state of Hamiltonians. Finding an appropriate parameterization of the quantum circuit is crucial to the success of VarQITE. This work provides guidance for constructing parameterized quantum circuits according to the locality and symmetries of the Hamiltonian. Our approa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.13598v1-abstract-full').style.display = 'inline'; document.getElementById('2307.13598v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.13598v1-abstract-full" style="display: none;"> The variational quantum imaginary time evolution (VarQITE) algorithm is a near-term method to prepare the ground state and Gibbs state of Hamiltonians. Finding an appropriate parameterization of the quantum circuit is crucial to the success of VarQITE. This work provides guidance for constructing parameterized quantum circuits according to the locality and symmetries of the Hamiltonian. Our approach can be used to implement the unitary and anti-unitary symmetries of a quantum system, which significantly reduces the depth and degree of freedom of the parameterized quantum circuits. To benchmark the proposed parameterized quantum circuits, we carry out VarQITE experiments on statistical models. Numerical results confirm that the symmetry-enhanced circuits outperform the frequently-used parametrized circuits in the literature. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.13598v1-abstract-full').style.display = 'none'; document.getElementById('2307.13598v1-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">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 5 figures, 4 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.05154">arXiv:2304.05154</a> <span> [<a href="https://arxiv.org/pdf/2304.05154">pdf</a>, <a href="https://arxiv.org/ps/2304.05154">ps</a>, <a href="https://arxiv.org/format/2304.05154">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"> Sensitive detection of millimeter wave electric field by driving trapped surface-state electrons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+M">Miao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y+F">Y. F. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+X+Y">X. Y. Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X+N">X. N. Feng</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+S+R">S. R. He</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y+F">Y. F. Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+L+F">L. F. Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.05154v1-abstract-short" style="display: inline;"> Sensitive detection of electromagnetic wave electric field plays an important role for electromagnetic communication and sensing. Here, we propose a quantum sensor to sensitively detect the electric field of the millimeter (mm) wave. The quantum sensor consists of many surface-state electrons trapped individually on liquid helium by a scalable electrode-network at the bottom of the helium film. On… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.05154v1-abstract-full').style.display = 'inline'; document.getElementById('2304.05154v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.05154v1-abstract-full" style="display: none;"> Sensitive detection of electromagnetic wave electric field plays an important role for electromagnetic communication and sensing. Here, we propose a quantum sensor to sensitively detect the electric field of the millimeter (mm) wave. The quantum sensor consists of many surface-state electrons trapped individually on liquid helium by a scalable electrode-network at the bottom of the helium film. On such a chip, each of the trapped electrons can be manipulated by the biased dc-current to deliver the strong spin-orbit couplings. The mm wave signal to be detected is applied to non-dispersively drive the orbital states of the trapped electrons, just resulting in the Stark shifts of the dressed spin-orbital states. As a consequence, the electric field of the applied mm wave could be detected sensitively by using the spin-echo interferometry of the long-lived spin states of the electrons trapped on liquid helium. The reasonable accuracy of the detection and also the feasibility of the proposal are discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.05154v1-abstract-full').style.display = 'none'; document.getElementById('2304.05154v1-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 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 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/2303.06604">arXiv:2303.06604</a> <span> [<a href="https://arxiv.org/pdf/2303.06604">pdf</a>, <a href="https://arxiv.org/format/2303.06604">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.107.062411">10.1103/PhysRevA.107.062411 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Robust phase metrology with hybrid quantum interferometers against particle losses </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X+N">X. N. Feng</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+D">D. He</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+L+F">L. F. Wei</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="2303.06604v1-abstract-short" style="display: inline;"> Entanglement is an important quantum resource to achieve high sensitive quantum metrology. However, the rapid decoherence of quantum entangled states, due to the unavoidable environment noise, result in practically the unwanted sharp drop of the measurement sensitivity. To overcome such a difficulty, here we propose a spin-oscillator hybrid quantum interferometer to achieve the desirable precise e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.06604v1-abstract-full').style.display = 'inline'; document.getElementById('2303.06604v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.06604v1-abstract-full" style="display: none;"> Entanglement is an important quantum resource to achieve high sensitive quantum metrology. However, the rapid decoherence of quantum entangled states, due to the unavoidable environment noise, result in practically the unwanted sharp drop of the measurement sensitivity. To overcome such a difficulty, here we propose a spin-oscillator hybrid quantum interferometer to achieve the desirable precise estimation of the parameter encoded in the vibrations of the oscillator. Differing from the conventional two-mode quantum interferometers input by the two-mode NOON state or entangled coherent states (ECS), whose achievable sensitivities are strongly limited by the decoherence of the entangled vibrational states, we demonstrate that the present interferometer, input by a spin-dependent two-mode entangled state, possesses a manifest advantage, i.e., the measurement sensitivity of the estimated parameter is not influenced by the decoherence from the spin-oscillator entanglement. This is because that, by applying a spin-oscillator disentangled operation, the information of the estimated parameter encoded originally in the vibrational degrees can be effectively transferred into the spin degree and then can be sensitively estimated by the precise spin-state population measurements. As consequence, the proposed hybrid quantum interferometer possesses a manifest robustness against the particle losses of the vibrational modes. Interestingly, the achieved phase measurement sensitivity can still surpass the SQL obviously, even if relatively large number of particle loss occurs in one of the two modes. The potential application of the proposed spin-oscillator hybrid quantum interferometer is also discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.06604v1-abstract-full').style.display = 'none'; document.getElementById('2303.06604v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.14279">arXiv:2302.14279</a> <span> [<a href="https://arxiv.org/pdf/2302.14279">pdf</a>, <a href="https://arxiv.org/format/2302.14279">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.108.022612">10.1103/PhysRevA.108.022612 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Critical behavior of Ising model by preparing thermal state on quantum computer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiaoyang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xu Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Hartung%2C+T">Tobias Hartung</a>, <a href="/search/quant-ph?searchtype=author&query=Jansen%2C+K">Karl Jansen</a>, <a href="/search/quant-ph?searchtype=author&query=Stornati%2C+P">Paolo Stornati</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.14279v2-abstract-short" style="display: inline;"> We simulate the critical behavior of the Ising model utilizing a thermal state prepared using quantum computing techniques. The preparation of the thermal state is based on the variational quantum imaginary time evolution (QITE) algorithm. The initial state of QITE is prepared as a classical product state, and we propose a systematic method to design the variational ansatz for QITE. We calculate t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.14279v2-abstract-full').style.display = 'inline'; document.getElementById('2302.14279v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.14279v2-abstract-full" style="display: none;"> We simulate the critical behavior of the Ising model utilizing a thermal state prepared using quantum computing techniques. The preparation of the thermal state is based on the variational quantum imaginary time evolution (QITE) algorithm. The initial state of QITE is prepared as a classical product state, and we propose a systematic method to design the variational ansatz for QITE. We calculate the specific heat and susceptibility of the long-range interacting Ising model and observe indications of the Ising criticality on a small lattice size. We find the results derived by the quantum algorithm are well consistent with the ones from exact diagonalization, both in the neighbourhood of the critical temperature and the low-temperature region. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.14279v2-abstract-full').style.display = 'none'; document.getElementById('2302.14279v2-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 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">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. A 108, 022612 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.10085">arXiv:2212.10085</a> <span> [<a href="https://arxiv.org/pdf/2212.10085">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"> Temperature sensing using nitrogen-vacancy centers with multiple-poly crystal directions based on Zeeman splitting </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xing%2C+L">Li Xing</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaojuan Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jintao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zheng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.10085v1-abstract-short" style="display: inline;"> We demonstrate a novel method based on the Zeeman splitting of electronic spins to improve the performance for temperature sensing of negatively-charged nitrogen-vacancy (NV) centers in multiple-poly diamond. The theoretical model for selection principle of resonance peaks corresponding to a single NV axis for determining the temperature dependence is clarified. The spectral linewidth is effective… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.10085v1-abstract-full').style.display = 'inline'; document.getElementById('2212.10085v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.10085v1-abstract-full" style="display: none;"> We demonstrate a novel method based on the Zeeman splitting of electronic spins to improve the performance for temperature sensing of negatively-charged nitrogen-vacancy (NV) centers in multiple-poly diamond. The theoretical model for selection principle of resonance peaks corresponding to a single NV axis for determining the temperature dependence is clarified. The spectral linewidth is effectively narrowed and the thermometer is insensitive to magnetic field fluctuations. Repeatability and accuracy of the relationship calibration between the zero-field splitting (ZFS) parameter D and temperature T in the range of 298 K to 323 K is significantly improved, and the results of coefficient dD/dT is 75.33 kHz/K. Finally, this method promotes the average temperature measurement sensitivity (below 10 Hz) of our setup from 0.49 K/Hz1/2 to 0.22 K/Hz1/2. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.10085v1-abstract-full').style.display = 'none'; document.getElementById('2212.10085v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.08090">arXiv:2212.08090</a> <span> [<a href="https://arxiv.org/pdf/2212.08090">pdf</a>, <a href="https://arxiv.org/format/2212.08090">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/PhysRevB.107.094309">10.1103/PhysRevB.107.094309 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Absence of logarithmic and algebraic scaling entanglement phases due to skin effect </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xu Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Shuo Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Shu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+W">Wenan 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="2212.08090v3-abstract-short" style="display: inline;"> Measurement-induced phase transition in the presence of competition between projective measurement and random unitary evolution has attracted increasing attention due to the rich phenomenology of entanglement structures. However, in open quantum systems with free fermions, a generalized measurement with conditional feedback can induce skin effect and render the system short-range entangled without… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.08090v3-abstract-full').style.display = 'inline'; document.getElementById('2212.08090v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.08090v3-abstract-full" style="display: none;"> Measurement-induced phase transition in the presence of competition between projective measurement and random unitary evolution has attracted increasing attention due to the rich phenomenology of entanglement structures. However, in open quantum systems with free fermions, a generalized measurement with conditional feedback can induce skin effect and render the system short-range entangled without any entanglement transition, meaning the system always remains in the ``area law'' entanglement phase. In this work, we demonstrate that the power-law long-range hopping does not alter the absence of entanglement transition brought on by the measurement-induced skin effect for systems with open boundary conditions. In addition, for the finite-size systems, we discover an algebraic scaling $S(L, L/4)\sim L^{3/2-p}$ when the power-law exponent $p$ of long-range hopping is relatively small. For systems with periodic boundary conditions, we find that the measurement-induced skin effect disappears and observe entanglement phase transitions among ``algebraic law'', ``logarithmic law'', and ``area law'' phases. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.08090v3-abstract-full').style.display = 'none'; document.getElementById('2212.08090v3-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 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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+3 pages, 11+4 figures, improve Sec. IV and abstract, add figures and references</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 107, 094309 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.02695">arXiv:2212.02695</a> <span> [<a href="https://arxiv.org/pdf/2212.02695">pdf</a>, <a href="https://arxiv.org/ps/2212.02695">ps</a>, <a href="https://arxiv.org/format/2212.02695">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"> High-dimensional quantum key distribution using energy-time entanglement over 242 km partially deployed fiber </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jingyuan Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+Z">Zhihao Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+D">Dongning Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei 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="2212.02695v1-abstract-short" style="display: inline;"> Entanglement-based quantum key distribution (QKD) is an essential ingredient in quantum communication, owing to the property of source-independent security and the potential on constructing large-scale quantum communication networks. However, implementation of entanglement-based QKD over long-distance optical fiber links is still challenging, especially over deployed fibers. In this work, we repor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.02695v1-abstract-full').style.display = 'inline'; document.getElementById('2212.02695v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.02695v1-abstract-full" style="display: none;"> Entanglement-based quantum key distribution (QKD) is an essential ingredient in quantum communication, owing to the property of source-independent security and the potential on constructing large-scale quantum communication networks. However, implementation of entanglement-based QKD over long-distance optical fiber links is still challenging, especially over deployed fibers. In this work, we report an experimental QKD using energy-time entangled photon pairs that transmit over optical fibers of 242 km (including a section of 19 km deployed fibers). High-quality entanglement distribution is verified by Franson-type interference with raw fringe visibilities of 94.1$\pm$1.9% and %92.4$\pm$5.4% in two non-orthogonal bases. The QKD is realized through the protocol of dispersive-optics QKD. A high-dimensional encoding is applied to utilize coincidence counts more efficiently. Using reliable, high-accuracy time synchronization technology, the system operates continuously for more than 7 days, even without active polarization or phase calibration. We ultimately generate secure keys with secure key rates of 0.22 bps and 0.06 bps in asymptotic and finite-size regime,respectively. This system is compatible with existing telecommunication infrastructures, showing great potential on realizing large-scale quantum communication networks in future. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.02695v1-abstract-full').style.display = 'none'; document.getElementById('2212.02695v1-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> 5 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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, 4 figures, 51 references</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.07264">arXiv:2210.07264</a> <span> [<a href="https://arxiv.org/pdf/2210.07264">pdf</a>, <a href="https://arxiv.org/format/2210.07264">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="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.4.030333">10.1103/PRXQuantum.4.030333 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement-induced phase transitions on dynamical quantum trees </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaozhou Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Skinner%2C+B">Brian Skinner</a>, <a href="/search/quant-ph?searchtype=author&query=Nahum%2C+A">Adam Nahum</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="2210.07264v2-abstract-short" style="display: inline;"> Monitored many-body systems fall broadly into two dynamical phases, ``entangling'' or ``disentangling'', separated by a transition as a function of the rate at which measurements are made on the system. Producing an analytical theory of this measurement-induced transition is an outstanding challenge. Recent work made progress in the context of tree tensor networks, which can be related to all-to-a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.07264v2-abstract-full').style.display = 'inline'; document.getElementById('2210.07264v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.07264v2-abstract-full" style="display: none;"> Monitored many-body systems fall broadly into two dynamical phases, ``entangling'' or ``disentangling'', separated by a transition as a function of the rate at which measurements are made on the system. Producing an analytical theory of this measurement-induced transition is an outstanding challenge. Recent work made progress in the context of tree tensor networks, which can be related to all-to-all quantum circuit dynamics with forced (postselected) measurement outcomes. So far, however, there are no exact solutions for dynamics of spin-1/2 degrees of freedom (qubits) with ``real'' measurements, whose outcome probabilities are sampled according to the Born rule. Here we define dynamical processes for qubits, with real measurements, that have a tree-like spacetime interaction graph, either collapsing or expanding the system as a function of time. The former case yields an exactly solvable measurement transition. We explore these processes analytically and numerically, exploiting the recursive structure of the tree. We compare the case of ``real'' measurements with the case of ``forced'' measurements. Both cases show a transition at a nontrivial value of the measurement strength, with the real measurement case exhibiting a smaller entangling phase. Both exhibit exponential scaling of the entanglement near the transition, but they differ in the value of a critical exponent. An intriguing difference between the two cases is that the real measurement case lies at the boundary between two distinct types of critical scaling. On the basis of our results we propose a protocol for realizing a measurement phase transition experimentally via an expansion process. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.07264v2-abstract-full').style.display = 'none'; document.getElementById('2210.07264v2-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 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 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">27 pages, 13 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 4, 030333(2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.05184">arXiv:2210.05184</a> <span> [<a href="https://arxiv.org/pdf/2210.05184">pdf</a>, <a href="https://arxiv.org/format/2210.05184">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"> Size optimization of CNOT circuits on NISQ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+A">Anpeng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiutao Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+S">Shengyuan Xu</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="2210.05184v1-abstract-short" style="display: inline;"> Quantum computers in practice today require strict memory constraints, where 2-qubit operations can only be performed between the qubits closest to each other in a graph structure. So a quantum circuit must undergo a transformation to the graph before it can be implemented. In this paper, we study the optimization of the CNOT circuits on some noisy intermediate-scale quantum(NISQ) devices. Compare… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.05184v1-abstract-full').style.display = 'inline'; document.getElementById('2210.05184v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.05184v1-abstract-full" style="display: none;"> Quantum computers in practice today require strict memory constraints, where 2-qubit operations can only be performed between the qubits closest to each other in a graph structure. So a quantum circuit must undergo a transformation to the graph before it can be implemented. In this paper, we study the optimization of the CNOT circuits on some noisy intermediate-scale quantum(NISQ) devices. Compared with previous works, we decompose it into two sub-problems: optimization with a given initial qubit distribution and optimization without limitations of initial qubit distribution. We find that most of the previous researches focused on the first sub-problem, and ignored the influence of different distribution of qubits in the same topology structure on the optimization results. In this paper, We take both sub-problems into account and give some new optimization algorithms. In short, our method is divided into two steps: matrix optimization and routing optimization. We implement matrix optimization with the algorithm in [XZL+20] and put forward a new heuristic algorithm with MILP method which can solve the second step. We implement our algorithm on IBM20 and some other NISQ devices, the results are better than most other methods in our experiment. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.05184v1-abstract-full').style.display = 'none'; document.getElementById('2210.05184v1-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">originally announced</span> October 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.02469">arXiv:2210.02469</a> <span> [<a href="https://arxiv.org/pdf/2210.02469">pdf</a>, <a href="https://arxiv.org/format/2210.02469">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.107.045137">10.1103/PhysRevB.107.045137 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exact solution for the filling-induced thermalization transition in a 1D fracton system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pozderac%2C+C">Calvin Pozderac</a>, <a href="/search/quant-ph?searchtype=author&query=Speck%2C+S">Steven Speck</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaozhou Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Huse%2C+D+A">David A. Huse</a>, <a href="/search/quant-ph?searchtype=author&query=Skinner%2C+B">Brian Skinner</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="2210.02469v1-abstract-short" style="display: inline;"> We study a random circuit model of constrained fracton dynamics, in which particles on a one-dimensional lattice undergo random local motion subject to both charge and dipole moment conservation. The configuration space of this system exhibits a continuous phase transition between a weakly fragmented ("thermalizing") phase and a strongly fragmented ("nonthermalizing") phase as a function of the nu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.02469v1-abstract-full').style.display = 'inline'; document.getElementById('2210.02469v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.02469v1-abstract-full" style="display: none;"> We study a random circuit model of constrained fracton dynamics, in which particles on a one-dimensional lattice undergo random local motion subject to both charge and dipole moment conservation. The configuration space of this system exhibits a continuous phase transition between a weakly fragmented ("thermalizing") phase and a strongly fragmented ("nonthermalizing") phase as a function of the number density of particles. Here, by mapping to two different problems in combinatorics, we identify an exact solution for the critical density $n_c$. Specifically, when evolution proceeds by operators that act on $\ell$ contiguous sites, the critical density is given by $n_c = 1/(\ell -2)$. We identify the critical scaling near the transition, and we show that there is a universal value of the correlation length exponent $谓= 2$. We confirm our theoretical results with numeric simulations. In the thermalizing phase the dynamical exponent is subdiffusive: $z=4$, while at the critical point it increases to $z_c \gtrsim 6$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.02469v1-abstract-full').style.display = 'none'; document.getElementById('2210.02469v1-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> 5 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">17 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/2208.14639">arXiv:2208.14639</a> <span> [<a href="https://arxiv.org/pdf/2208.14639">pdf</a>, <a href="https://arxiv.org/format/2208.14639">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="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/10.1063/5.0152838">10.1063/5.0152838 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Analytical harmonic vibrational frequencies with VV10-containing density functionals: Theory, efficient implementation, and benchmark assessments </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liang%2C+J">Jiashu Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xintian Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Head-Gordon%2C+M">Martin Head-Gordon</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="2208.14639v2-abstract-short" style="display: inline;"> VV10 is a powerful nonlocal density functional for long-range correlation that is used to include dispersion effects in many modern density functionals such as the meta-generalized gradient approximation (mGGA), B97M-V, the hybrid GGA, 蠅B97X-V and the hybrid mGGA, 蠅B97M-V. While energies and analytical gradients for VV10 are already widely available, this study reports the first derivation and eff… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.14639v2-abstract-full').style.display = 'inline'; document.getElementById('2208.14639v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.14639v2-abstract-full" style="display: none;"> VV10 is a powerful nonlocal density functional for long-range correlation that is used to include dispersion effects in many modern density functionals such as the meta-generalized gradient approximation (mGGA), B97M-V, the hybrid GGA, 蠅B97X-V and the hybrid mGGA, 蠅B97M-V. While energies and analytical gradients for VV10 are already widely available, this study reports the first derivation and efficient implementation of the analytical second derivatives of the VV10 energy. The additional compute cost of the VV10 contributions to analytical frequencies is shown to be small in all but the smallest basis sets for recommended grid sizes. This study also reports the assessment of VV10-containing functionals for predicting harmonic frequencies using the analytical second derivative code. The contribution of VV10 to simulating harmonic frequencies is shown to be small for small molecules but important for systems where weak interactions are important, such as water clusters. In the latter cases, B97M-V, 蠅B97M-V, and 蠅B97X-V perform very well. The convergence of frequencies with respect to grid size and atomic orbital basis set size is studied and recommendations reported. Finally, scaling factors to allow comparison of scaled harmonic frequencies with experimental fundamental frequencies and to predict zero-point vibrational energy are presented for some recently developed functionals (including r2SCAN, B97M-V, 蠅B97X-V, M06-SX, and 蠅B97M-V). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.14639v2-abstract-full').style.display = 'none'; document.getElementById('2208.14639v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 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">Comments:</span> <span class="has-text-grey-dark mathjax">30 pages, 5 figures, 4 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.12467">arXiv:2208.12467</a> <span> [<a href="https://arxiv.org/pdf/2208.12467">pdf</a>, <a href="https://arxiv.org/format/2208.12467">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link 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="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.106.125102">10.1103/PhysRevB.106.125102 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Periodic Clifford symmetry algebras on flux lattices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yue-Xin Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z+Y">Z. Y. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaolong Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S+A">Shengyuan A. Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y+X">Y. X. Zhao</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="2208.12467v1-abstract-short" style="display: inline;"> Real Clifford algebras play a fundamental role in the eight real Altland-Zirnbauer symmetry classes and the classification tables of topological phases. Here, we present another elegant realization of real Clifford algebras in the $d$-dimensional spinless rectangular lattices with $蟺$ flux per plaquette. Due to the $T$-invariant flux configuration, real Clifford algebras are realized as projective… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.12467v1-abstract-full').style.display = 'inline'; document.getElementById('2208.12467v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.12467v1-abstract-full" style="display: none;"> Real Clifford algebras play a fundamental role in the eight real Altland-Zirnbauer symmetry classes and the classification tables of topological phases. Here, we present another elegant realization of real Clifford algebras in the $d$-dimensional spinless rectangular lattices with $蟺$ flux per plaquette. Due to the $T$-invariant flux configuration, real Clifford algebras are realized as projective symmetry algebras of lattice symmetries. Remarkably, $d$ mod $8$ exactly corresponds to the eight Morita equivalence classes of real Clifford algebras with eightfold Bott periodicity, resembling the eight real Altland-Zirnbauer classes. The representation theory of Clifford algebras determines the degree of degeneracy of band structures, both at generic $k$ points and at high-symmetry points of the Brillouin zone. Particularly, we demonstrate that the large degeneracy at high-symmetry points offers a rich resource for forming novel topological states by various dimerization patterns, including a $3$D higher-order semimetal state with double-charged bulk nodal loops and hinge modes, a $4$D nodal surface semimetal with $3$D surface solid-ball zero modes, and $4$D M枚bius topological insulators with a eightfold surface nodal point or a fourfold surface nodal ring. Our theory can be experimentally realized in artificial crystals by their engineerable $\mathbb{Z}_2$ gauge fields and capability to simulate higher dimensional systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.12467v1-abstract-full').style.display = 'none'; document.getElementById('2208.12467v1-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 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">Comments:</span> <span class="has-text-grey-dark mathjax">8 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/2207.10935">arXiv:2207.10935</a> <span> [<a href="https://arxiv.org/pdf/2207.10935">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"> Controllable Entanglement Distribution Network Based on Silicon Quantum Photonics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+D">Dongning Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jingyuan Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+X">Xiaosong Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei 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="2207.10935v1-abstract-short" style="display: inline;"> The entanglement distribution network connects remote users through sharing entanglement resources, which is essential for realizing quantum internet. We proposed a controllable entanglement distribution network (c-EDN) based on a silicon quantum photonic chip. The entanglement resources were generated by a quantum light source array based on spontaneous four-wave mixing (SFWM) in silicon waveguid… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.10935v1-abstract-full').style.display = 'inline'; document.getElementById('2207.10935v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.10935v1-abstract-full" style="display: none;"> The entanglement distribution network connects remote users through sharing entanglement resources, which is essential for realizing quantum internet. We proposed a controllable entanglement distribution network (c-EDN) based on a silicon quantum photonic chip. The entanglement resources were generated by a quantum light source array based on spontaneous four-wave mixing (SFWM) in silicon waveguides and distributed to different users through time-reversed Hong-Ou-Mandel interferences in on-chip Mach-Zehnder interferometers with thermal phase shifters. A chip sample was designed and fabricated, supporting a c-EDN with 3 subnets and 24 users. The network topology of entanglement distributions could be reconfigured in three network states by controlling the quantum interferences through the phase shifters, which was demonstrated experimentally. Furthermore, a reconfigurable entanglement-based QKD network was realized as an application of the c-EDN. The reconfigurable network topology makes the c-EDN suitable for future quantum networks requiring complicated network control and management. Moreover, it is also shows that silicon quantum photonic chips have great potential for large-scale c-EDN, thanks to their capacities on generating and manipulating plenty of entanglement resources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.10935v1-abstract-full').style.display = 'none'; document.getElementById('2207.10935v1-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 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.12221">arXiv:2206.12221</a> <span> [<a href="https://arxiv.org/pdf/2206.12221">pdf</a>, <a href="https://arxiv.org/format/2206.12221">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/PhysRevResearch.5.023005">10.1103/PhysRevResearch.5.023005 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Vibration-Assisted Multi-Photon Resonance and Multi-Ion Excitation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Shao%2C+W">Wenjun Shao</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xun-Li Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Jian Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+L">Liang-Liang Wang</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="2206.12221v1-abstract-short" style="display: inline;"> We investigate the multi-photon resonance and multi-ion excitation in a single-mode cavity with identical vibrating ion-qubits, which enables the tripartite interaction among the internal states of ions, the cavity mode and the ions' vibrational motion. Under particular resonant conditions, we derive effective Hamiltonians for the three-photon and the three-excitation cases, respectively, and find… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.12221v1-abstract-full').style.display = 'inline'; document.getElementById('2206.12221v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.12221v1-abstract-full" style="display: none;"> We investigate the multi-photon resonance and multi-ion excitation in a single-mode cavity with identical vibrating ion-qubits, which enables the tripartite interaction among the internal states of ions, the cavity mode and the ions' vibrational motion. Under particular resonant conditions, we derive effective Hamiltonians for the three-photon and the three-excitation cases, respectively, and find that the magnitude of the effective coupling energy can be tuned through the vibration mode, allowing for manipulations of ion-photon coupling in experiments. Furthermore, we analyze the system dynamics of our proposed setups and demonstrate the Rabi oscillation behaviors in these systems with dissipation effects. We propose our system as a versatile platform for the exploration of entangled multi-qubit physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.12221v1-abstract-full').style.display = 'none'; document.getElementById('2206.12221v1-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 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">25 pages, 18 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Research 5, 023005 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.13208">arXiv:2202.13208</a> <span> [<a href="https://arxiv.org/pdf/2202.13208">pdf</a>, <a href="https://arxiv.org/format/2202.13208">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="Other Condensed Matter">cond-mat.other</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 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.2c00160">10.1021/acs.jctc.2c00160 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Revisiting the performance of time-dependent density functional theory for electronic excitations: Assessment of 43 popular and recently developed functionals from rungs one to four </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liang%2C+J">Jiashu Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xintian Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Hait%2C+D">Diptarka Hait</a>, <a href="/search/quant-ph?searchtype=author&query=Head-Gordon%2C+M">Martin Head-Gordon</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="2202.13208v3-abstract-short" style="display: inline;"> In this paper, the performance of more than 40 popular or recently developed density functionals is assessed for the calculation of 463 vertical excitation energies against the large and accurate QuestDB benchmark set. For this purpose, the Tamm-Dancoff approximation offers a good balance between performance and accuracy. The functionals $蠅$B97X-D and BMK are found to offer the best performance ov… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.13208v3-abstract-full').style.display = 'inline'; document.getElementById('2202.13208v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.13208v3-abstract-full" style="display: none;"> In this paper, the performance of more than 40 popular or recently developed density functionals is assessed for the calculation of 463 vertical excitation energies against the large and accurate QuestDB benchmark set. For this purpose, the Tamm-Dancoff approximation offers a good balance between performance and accuracy. The functionals $蠅$B97X-D and BMK are found to offer the best performance overall with a Root-Mean Square Error (RMSE) of 0.28 eV, better than the computationally more demanding CIS(D) wavefunction method with a RMSE of 0.36 eV. The results also suggest that Jacob's ladder still holds for TDDFT excitation energies, though hybrid meta-GGAs are not generally better than hybrid GGAs. Effects of basis set convergence, gauge invariance correction to meta-GGAs, and nonlocal correlation (VV10) are also studied, and practical basis set recommendations are provided. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.13208v3-abstract-full').style.display = 'none'; document.getElementById('2202.13208v3-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 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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, 8 figures; 8 pages, 7 figures for supporting info</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.13154">arXiv:2202.13154</a> <span> [<a href="https://arxiv.org/pdf/2202.13154">pdf</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="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.abp8892">10.1126/sciadv.abp8892 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> On-chip mechanical exceptional points based on an optomechanical zipper cavity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+N">Ning Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Q">Qiancheng Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong 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="2202.13154v1-abstract-short" style="display: inline;"> Exceptional points (EPs) represent a distinct type of spectral singularity in non-Hermitian systems, and intriguing physics concepts have been studied with optical EPs recently. As a system beyond photonics, the mechanical oscillators coupling with many physical systems are expected to be further exploited EPs for mechanical sensing, topology energy transfer, nonreciprocal dynamics etc. In this st… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.13154v1-abstract-full').style.display = 'inline'; document.getElementById('2202.13154v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.13154v1-abstract-full" style="display: none;"> Exceptional points (EPs) represent a distinct type of spectral singularity in non-Hermitian systems, and intriguing physics concepts have been studied with optical EPs recently. As a system beyond photonics, the mechanical oscillators coupling with many physical systems are expected to be further exploited EPs for mechanical sensing, topology energy transfer, nonreciprocal dynamics etc. In this study, we demonstrated on-chip mechanical EPs with a silicon optomechanical zipper cavity, wherein two near-degenerate mechanical breathing modes are coupled via a single co-localized optical mode. By tailoring the dissipative and coherent couplings between two mechanical oscillators, the spectral splitting with 1/2 order response, a distinctive feature of EP, was observed successfully. Our work provides an integrated platform for investigating the physics related to mechanical EPs on silicon chips and suggests their possible applications for ultrasensitive measurements. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.13154v1-abstract-full').style.display = 'none'; document.getElementById('2202.13154v1-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 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.15522">arXiv:2111.15522</a> <span> [<a href="https://arxiv.org/pdf/2111.15522">pdf</a>, <a href="https://arxiv.org/format/2111.15522">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> </div> <p class="title is-5 mathjax"> Model-Independent Error Mitigation in Parametric Quantum Circuits and Depolarizing Projection of Quantum Noise </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiaoyang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xu Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Funcke%2C+L">Lena Funcke</a>, <a href="/search/quant-ph?searchtype=author&query=Hartung%2C+T">Tobias Hartung</a>, <a href="/search/quant-ph?searchtype=author&query=Jansen%2C+K">Karl Jansen</a>, <a href="/search/quant-ph?searchtype=author&query=K%C3%BChn%2C+S">Stefan K眉hn</a>, <a href="/search/quant-ph?searchtype=author&query=Polykratis%2C+G">Georgios Polykratis</a>, <a href="/search/quant-ph?searchtype=author&query=Stornati%2C+P">Paolo Stornati</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="2111.15522v1-abstract-short" style="display: inline;"> Finding ground states and low-lying excitations of a given Hamiltonian is one of the most important problems in many fields of physics. As a novel approach, quantum computing on Noisy Intermediate-Scale Quantum (NISQ) devices offers the prospect to efficiently perform such computations and may eventually outperform classical computers. However, current quantum devices still suffer from inherent qu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.15522v1-abstract-full').style.display = 'inline'; document.getElementById('2111.15522v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.15522v1-abstract-full" style="display: none;"> Finding ground states and low-lying excitations of a given Hamiltonian is one of the most important problems in many fields of physics. As a novel approach, quantum computing on Noisy Intermediate-Scale Quantum (NISQ) devices offers the prospect to efficiently perform such computations and may eventually outperform classical computers. However, current quantum devices still suffer from inherent quantum noise. In this work, we propose an error mitigation scheme suitable for parametric quantum circuits. This scheme is based on projecting a general quantum noise channel onto depolarization errors. Our method can efficiently reduce errors in quantum computations, which we demonstrate by carrying out simulations both on classical and IBM's quantum devices. In particular, we test the performance of the method by computing the mass gap of the transverse-field Ising model using the variational quantum eigensolver algorithm. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.15522v1-abstract-full').style.display = 'none'; document.getElementById('2111.15522v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 4 figures, Proceedings of the 38th International Symposium on Lattice Field Theory, 26th-30th July 2021, Zoom/Gather@Massachusetts Institute of Technology</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> MIT-CTP/5354 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.05594">arXiv:2111.05594</a> <span> [<a href="https://arxiv.org/pdf/2111.05594">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="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/10.1002/lpor.202200388">10.1002/lpor.202200388 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Room-temperature on-chip generation of heralded single photons with switchable orbital angular momentum </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong 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="2111.05594v2-abstract-short" style="display: inline;"> In quantum optics, orbital angular momentum (OAM) is very promising to achieve high-dimensional quantum states due to the nature of infinite and discrete eigenvalue, which is quantized by the topological charge of l. Here, a heralded single-photon source with switchable OAM modes is proposed and demonstrated on silicon chip. At room-temperature, the heralded single photons with 11 OAM modes (l=2~6… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.05594v2-abstract-full').style.display = 'inline'; document.getElementById('2111.05594v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.05594v2-abstract-full" style="display: none;"> In quantum optics, orbital angular momentum (OAM) is very promising to achieve high-dimensional quantum states due to the nature of infinite and discrete eigenvalue, which is quantized by the topological charge of l. Here, a heralded single-photon source with switchable OAM modes is proposed and demonstrated on silicon chip. At room-temperature, the heralded single photons with 11 OAM modes (l=2~6, -6~-1) have been successfully generated and switched through thermo-optical effect. We believe that such an integrated quantum source with multiple OAM modes and operating at room-temperature would provide a practical platform for high-dimensional quantum information processing. Moreover, our proposed architecture can also be extended to other material systems to further improve the performance of OAM quantum source. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.05594v2-abstract-full').style.display = 'none'; document.getElementById('2111.05594v2-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 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Laser Photonics Rev.2022, 2200388 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.13812">arXiv:2109.13812</a> <span> [<a href="https://arxiv.org/pdf/2109.13812">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Biological Physics">physics.bio-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"> Measurement of single-cell elasticity by nanodiamond-sensing of non-local deformation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cui%2C+Y">Yue Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Leong%2C+W">Weng-Hang Leong</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+C">Chu-Feng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Xia%2C+K">Kangwei Xia</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xi Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Gergely%2C+C">Csilla Gergely</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Ren-Bao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Quan 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="2109.13812v1-abstract-short" style="display: inline;"> Nano-indentation based on, e.g., atomic force microscopy (AFM), can measure single cell elasticity with high spatial resolution and sensitivity, but relating the data to cell mechanical properties depends on modeling that requires knowledge about the local contact between the indentation tip and the material, which is unclear in most cases. Here we use the orientation sensing by nitrogen-vacancy c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.13812v1-abstract-full').style.display = 'inline'; document.getElementById('2109.13812v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.13812v1-abstract-full" style="display: none;"> Nano-indentation based on, e.g., atomic force microscopy (AFM), can measure single cell elasticity with high spatial resolution and sensitivity, but relating the data to cell mechanical properties depends on modeling that requires knowledge about the local contact between the indentation tip and the material, which is unclear in most cases. Here we use the orientation sensing by nitrogen-vacancy centers in nanodiamonds to chart the non-local deformation of fixed HeLa cells induced by AFM indentation, providing data for studying cell mechanics without requiring detailed knowledge about the local contact. The competition between the elasticity and capillarity on the cells is observed. We show that the apparent elastic moduli of the cells would have been overestimated if the capillarity is not considered (as in most previous studies using local depth-loading data). We also find reduction of both elastic moduli and surface tensions due to depolymerization of the actin cytoskeleton structure. This work demonstrates that, under shallow indentation, the nanodiamond sensing of non-local deformation with nanometer precision is particularly suitable for studying mechanics of cells. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.13812v1-abstract-full').style.display = 'none'; document.getElementById('2109.13812v1-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, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">28 pages (4 figures) + 12 pages (10 figures)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.05445">arXiv:2109.05445</a> <span> [<a href="https://arxiv.org/pdf/2109.05445">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link 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"> Zero-field magnetometry using hyperfine-biased nitrogen-vacancy centers near diamond surfaces </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+N">Ning Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+C">Chu-Feng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+J">Jing-Wei Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xi Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Leong%2C+W">Weng-Hang Leong</a>, <a href="/search/quant-ph?searchtype=author&query=Finkler%2C+A">Amit Finkler</a>, <a href="/search/quant-ph?searchtype=author&query=Denisenko%2C+A">Andrej Denisenko</a>, <a href="/search/quant-ph?searchtype=author&query=Wrachtrup%2C+J">J枚rg Wrachtrup</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Quan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Ren-Bao 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="2109.05445v1-abstract-short" style="display: inline;"> Shallow nitrogen-vacancy (NV) centers in diamond are promising for nano-magnetometry for they can be placed proximate to targets. To study the intrinsic magnetic properties, zero-field magnetometry is desirable. However, for shallow NV centers under zero field, the strain near diamond surfaces would cause level anti-crossing between the spin states, leading to clock transitions whose frequencies a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.05445v1-abstract-full').style.display = 'inline'; document.getElementById('2109.05445v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.05445v1-abstract-full" style="display: none;"> Shallow nitrogen-vacancy (NV) centers in diamond are promising for nano-magnetometry for they can be placed proximate to targets. To study the intrinsic magnetic properties, zero-field magnetometry is desirable. However, for shallow NV centers under zero field, the strain near diamond surfaces would cause level anti-crossing between the spin states, leading to clock transitions whose frequencies are insensitive to magnetic signals. Furthermore, the charge noises from the surfaces would induce extra spin decoherence and hence reduce the magnetic sensitivity. Here we demonstrate that the relatively strong hyperfine coupling (130 MHz) from a first-shell 13C nuclear spin can provide an effective bias field to an NV center spin so that the clock-transition condition is broken and the charge noises are suppressed. The hyperfine bias enhances the dc magnetic sensitivity by a factor of 22 in our setup. With the charge noises suppressed by the strong hyperfine field, the ac magnetometry under zero field also reaches the limit set by decoherence due to the nuclear spin bath. In addition, the 130 MHz splitting of the NV center spin transitions allows relaxometry of magnetic noises simultaneously at two well-separated frequencies (~2.870 +/- 0.065 GHz), providing (low-resolution) spectral information of high-frequency noises under zero field. The hyperfine-bias enhanced zero-field magnetometry can be combined with dynamical decoupling to enhance single-molecule magnetic resonance spectroscopy and to improve the frequency resolution in nanoscale magnetic resonance imaging. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.05445v1-abstract-full').style.display = 'none'; document.getElementById('2109.05445v1-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 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.02975">arXiv:2106.02975</a> <span> [<a href="https://arxiv.org/pdf/2106.02975">pdf</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 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/10.1063/5.0046080">10.1063/5.0046080 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cavity Quantum Electrodynamics Design with Single Photon Emitters in Hexagonal Boron Nitride </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yanan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+J">Jaesung Lee</a>, <a href="/search/quant-ph?searchtype=author&query=Berezovsky%2C+J">Jesse Berezovsky</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+P+X+-">Philip X. -L. Feng</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.02975v1-abstract-short" style="display: inline;"> Hexagonal boron nitride (h-BN), a prevalent insulating crystal for dielectric and encapsulation layers in two-dimensional (2D) nanoelectronics and a structural material in 2D nanoelectromechanical systems (NEMS), has also rapidly emerged as a promising platform for quantum photonics with the recent discovery of optically active defect centers and associated spin states. Combined with measured emis… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.02975v1-abstract-full').style.display = 'inline'; document.getElementById('2106.02975v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.02975v1-abstract-full" style="display: none;"> Hexagonal boron nitride (h-BN), a prevalent insulating crystal for dielectric and encapsulation layers in two-dimensional (2D) nanoelectronics and a structural material in 2D nanoelectromechanical systems (NEMS), has also rapidly emerged as a promising platform for quantum photonics with the recent discovery of optically active defect centers and associated spin states. Combined with measured emission characteristics, here we propose and numerically investigate the cavity quantum electrodynamics (cavity-QED) scheme incorporating these defect-enabled single photon emitters (SPEs) in h-BN microdisk resonators. The whispering-gallery nature of microdisks can support multiple families of cavity resonances with different radial and azimuthal mode indices simultaneously, overcoming the challenges in coinciding a single point defect with the maximum electric field of an optical mode both spatially and spectrally. The excellent characteristics of h-BN SPEs, including exceptional emission rate, considerably high Debye-Waller factor, and Fourier transform limited linewidth at room temperature, render strong coupling with the ratio of coupling to decay rates g/max(纬,\k{appa}) predicated as high as 500. This study not only provides insight into the emitter-cavity interaction, but also contributes toward realizing h-BN photonic components, such as low-threshold microcavity lasers and high-purity single photon sources, critical for linear optics quantum computing and quantum networking applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.02975v1-abstract-full').style.display = 'none'; document.getElementById('2106.02975v1-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> 5 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 Pages, 5 Figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Applied Physics Letters (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.11465">arXiv:2105.11465</a> <span> [<a href="https://arxiv.org/pdf/2105.11465">pdf</a>, <a href="https://arxiv.org/format/2105.11465">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="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.4.013053">10.1103/PhysRevResearch.4.013053 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Hilbert space fragmentation produces a "fracton Casimir effect" </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaozhou Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Skinner%2C+B">Brian Skinner</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.11465v3-abstract-short" style="display: inline;"> Fracton systems exhibit restricted mobility of their excitations due to the presence of higher-order conservation laws. Here we study the time evolution of a one-dimensional fracton system with charge and dipole moment conservation using a random unitary circuit description. Previous work has shown that when the random unitary operators act on four or more sites, an arbitrary initial state eventua… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.11465v3-abstract-full').style.display = 'inline'; document.getElementById('2105.11465v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.11465v3-abstract-full" style="display: none;"> Fracton systems exhibit restricted mobility of their excitations due to the presence of higher-order conservation laws. Here we study the time evolution of a one-dimensional fracton system with charge and dipole moment conservation using a random unitary circuit description. Previous work has shown that when the random unitary operators act on four or more sites, an arbitrary initial state eventually thermalizes via a universal subdiffusive dynamics. In contrast, a system evolving under three-site gates fails to thermalize due to strong "fragmentation" of the Hilbert space. Here we show that three-site gate dynamics causes a given initial state to evolve toward a highly nonthermal state on a time scale consistent with Brownian diffusion. Strikingly, the dynamics produces an effective attraction between isolated fractons or between a single fracton and the boundaries of the system, in analogy with the Casimir effect in quantum electrodynamics. We show how this attraction can be understood by exact mapping to a simple classical statistical mechanics problem, which we solve exactly for the case of an initial state with either one or two fractons. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.11465v3-abstract-full').style.display = 'none'; document.getElementById('2105.11465v3-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8+3 pages,8 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys.Rev.Research 4, 013053(2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.04914">arXiv:2105.04914</a> <span> [<a href="https://arxiv.org/pdf/2105.04914">pdf</a>, <a href="https://arxiv.org/format/2105.04914">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"> Implementation of hybridly protected quantum gates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+C">Chunfeng Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+C">Chunfang Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+G">Gangcheng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xun-Li Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Yi%2C+X">Xuexi Yi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.04914v1-abstract-short" style="display: inline;"> We explore the implementation of hybridly protected quantum operations combining the merits of holonomy, dynamical decoupling approach and dephasing-free feature based on a simple and experimentally achievable spin model. The implementation of the quantum operations can be achieved in different physical systems with controllable parameters. The protected quantum operations are hence controllable,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.04914v1-abstract-full').style.display = 'inline'; document.getElementById('2105.04914v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.04914v1-abstract-full" style="display: none;"> We explore the implementation of hybridly protected quantum operations combining the merits of holonomy, dynamical decoupling approach and dephasing-free feature based on a simple and experimentally achievable spin model. The implementation of the quantum operations can be achieved in different physical systems with controllable parameters. The protected quantum operations are hence controllable, well-suited for resolving various quantum computation tasks, such as executing quantum error-correction codes or quantum error mitigation. Our scheme is based on experimentally achievable Hamiltonian with reduced requirement of computational resources and thus, it brings us closer towards realizing protected quantum operations for resolving quantum computation tasks in near-term quantum devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.04914v1-abstract-full').style.display = 'none'; document.getElementById('2105.04914v1-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 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 1 figure</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2103.07740">arXiv:2103.07740</a> <span> [<a href="https://arxiv.org/pdf/2103.07740">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"> Generation and dynamical manipulation of polarization entangled Bell states by a silicon quantum photonic circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+D">Dongning Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+J">Jingyuan Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+L">Lingjie Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei 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="2103.07740v1-abstract-short" style="display: inline;"> A silicon quantum photonic circuit was proposed and demonstrated as an integrated quantum light source for telecom band polarization entangled Bell state generation and dynamical manipulation. Biphoton states were firstly generated in four silicon waveguides by spontaneous four wave mixing. They were transformed to polarization entangled Bell states through on-chip quantum interference and quantum… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.07740v1-abstract-full').style.display = 'inline'; document.getElementById('2103.07740v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2103.07740v1-abstract-full" style="display: none;"> A silicon quantum photonic circuit was proposed and demonstrated as an integrated quantum light source for telecom band polarization entangled Bell state generation and dynamical manipulation. Biphoton states were firstly generated in four silicon waveguides by spontaneous four wave mixing. They were transformed to polarization entangled Bell states through on-chip quantum interference and quantum superposition, and then coupled to optical fibers. The property of polarization entanglement in generated photon pairs was demonstrated by two-photon interferences under two non-orthogonal polarization bases. The output state could be dynamically switched between two polarization entangled Bell states, which was demonstrated by the experiment of simplified Bell state measurement. The experiment results indicate that its manipulation speed supported a modulation rate of several tens kHz, showing its potential on applications of quantum communication and quantum information processing requiring dynamical quantum entangled Bell state control. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.07740v1-abstract-full').style.display = 'none'; document.getElementById('2103.07740v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.00833">arXiv:2101.00833</a> <span> [<a href="https://arxiv.org/pdf/2101.00833">pdf</a>, <a href="https://arxiv.org/format/2101.00833">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"> Expectation Synchronization Synthesis in Non-Markovian Open Quantum Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shikun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+K">Kun Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+D">Daoyi Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaoxue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+F">Feng Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.00833v2-abstract-short" style="display: inline;"> In this article, we investigate the problem of engineering synchronization in non-Markovian quantum systems. First, a time-convoluted linear quantum stochastic differential equation is derived which describes the Heisenberg evolution of a localized quantum system driven by multiple colored noise inputs. Then, we define quantum expectation synchronization in an augmented system consisting of two su… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.00833v2-abstract-full').style.display = 'inline'; document.getElementById('2101.00833v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.00833v2-abstract-full" style="display: none;"> In this article, we investigate the problem of engineering synchronization in non-Markovian quantum systems. First, a time-convoluted linear quantum stochastic differential equation is derived which describes the Heisenberg evolution of a localized quantum system driven by multiple colored noise inputs. Then, we define quantum expectation synchronization in an augmented system consisting of two subsystems. We prove that, for two homogenous subsystems, synchronization can always be synthesized without designing direct Hamiltonian coupling given that the degree of non-Markovianity is below a certain threshold. System parameters are explicitly designed to achieve quantum synchronization. Also, a numerical example is presented to illustrate our results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.00833v2-abstract-full').style.display = 'none'; document.getElementById('2101.00833v2-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 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2011.11319">arXiv:2011.11319</a> <span> [<a href="https://arxiv.org/pdf/2011.11319">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"> Fully connected entanglement-based quantum communication network without trusted node </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xu Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Xue%2C+R">Rong Xue</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Heqing Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei 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="2011.11319v1-abstract-short" style="display: inline;"> Quantum communication is developed owing to the theoretically proven security of quantum mechanics, which may become the main technique in future information security. However, most studies and implementations are limited to two or several parties. Herein, we propose a fully connected quantum communication network without a trusted node for a large number of users. Using flexible wavelength demult… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.11319v1-abstract-full').style.display = 'inline'; document.getElementById('2011.11319v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2011.11319v1-abstract-full" style="display: none;"> Quantum communication is developed owing to the theoretically proven security of quantum mechanics, which may become the main technique in future information security. However, most studies and implementations are limited to two or several parties. Herein, we propose a fully connected quantum communication network without a trusted node for a large number of users. Using flexible wavelength demultiplex/multiplex and space multiplex technologies, 40 users are fully connected simultaneously without a trusted node by a broadband energy-time entangled photon pair source. This network architecture may be widely deployed in real scenarios such as companies, schools, and communities owing to its simplicity, scalability, and high efficiency. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.11319v1-abstract-full').style.display = 'none'; document.getElementById('2011.11319v1-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 November, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2011.03250">arXiv:2011.03250</a> <span> [<a href="https://arxiv.org/pdf/2011.03250">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="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/10.1360/nso/20220019">10.1360/nso/20220019 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Programmable Unitary Operations for Orbital Angular Momentum Encoded States </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shikang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong 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="2011.03250v2-abstract-short" style="display: inline;"> We have proposed and demonstrated a scalable and efficient scheme for programmable unitary operations in orbital angular momentum (OAM) domain. Based on matrix decomposition into diagonal and Fourier factors, arbitrary matrix operators can be implemented only by diagonal matrices alternately acting on orbital angular momentum domain and azimuthal angle domain, which are linked by Fourier transform… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.03250v2-abstract-full').style.display = 'inline'; document.getElementById('2011.03250v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2011.03250v2-abstract-full" style="display: none;"> We have proposed and demonstrated a scalable and efficient scheme for programmable unitary operations in orbital angular momentum (OAM) domain. Based on matrix decomposition into diagonal and Fourier factors, arbitrary matrix operators can be implemented only by diagonal matrices alternately acting on orbital angular momentum domain and azimuthal angle domain, which are linked by Fourier transform. With numerical simulations, unitary matrices with dimensionality of 3*3 are designed and discussed for OAM domain. Meanwhile, the parallelism of our proposed scheme is also presented with two 3*3 matrices. Furthermore, as an alternative to verify our proposal, proof of principle experiments have been performed on path domain with the same matrix decomposition method, in which an average fidelity of 0.97 is evaluated through 80 experimental results with dimensionality of 3*3. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.03250v2-abstract-full').style.display = 'none'; document.getElementById('2011.03250v2-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 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 November, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">The manuscript includes abstract (about 150 words), text part (about 4700 words), 7 figures and 42 references</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> National Science Open, Volume 1, Issue 2: 20220019 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.06166">arXiv:2009.06166</a> <span> [<a href="https://arxiv.org/pdf/2009.06166">pdf</a>, <a href="https://arxiv.org/ps/2009.06166">ps</a>, <a href="https://arxiv.org/format/2009.06166">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.14.064023">10.1103/PhysRevApplied.14.064023 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Atom-light hybrid quantum gyroscope </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yuan Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+J">Jinxian Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaotian Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L+Q">L. Q. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+C">Chun-Hua Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weiping 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="2009.06166v1-abstract-short" style="display: inline;"> A new type of atom-light hybrid quantum gyroscope (ALHQG) is proposed due to its high rotation sensitivity. It consists of an optical Sagnac loop to couple rotation rate and an atomic ensemble as quantum beam splitter/recombiner (QBS/C) based on atomic Raman amplification process to realize the splitting and recombination of the optical wave and the atomic spin wave. The rotation sensitivity can b… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.06166v1-abstract-full').style.display = 'inline'; document.getElementById('2009.06166v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.06166v1-abstract-full" style="display: none;"> A new type of atom-light hybrid quantum gyroscope (ALHQG) is proposed due to its high rotation sensitivity. It consists of an optical Sagnac loop to couple rotation rate and an atomic ensemble as quantum beam splitter/recombiner (QBS/C) based on atomic Raman amplification process to realize the splitting and recombination of the optical wave and the atomic spin wave. The rotation sensitivity can be enhanced by the quantum correlation between Sagnac loop and QBS/C. The optimal working condition is investigated to achieve the best sensitivity. The numerical results show that the rotation sensitivity can beat the standard quantum limit (SQL) in ideal condition. Even in the presence of the attenuation under practical condition, the best sensitivity of the ALHQG can still beat the SQL and is better than that of a fiber optic gyroscope (FOG). Such an ALHQG could be practically applied for modern inertial navigation system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.06166v1-abstract-full').style.display = 'none'; document.getElementById('2009.06166v1-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 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">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. Applied 14, 064023 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2005.06783">arXiv:2005.06783</a> <span> [<a href="https://arxiv.org/pdf/2005.06783">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="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/PhysRevApplied.14.024027">10.1103/PhysRevApplied.14.024027 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Programmable coherent linear quantum operations with high-dimensional optical spatial modes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shikang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+S+Z+X">Shan Zhang Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Barnett%2C+S+M">Stephen M. Barnett</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong 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="2005.06783v1-abstract-short" style="display: inline;"> A simple and flexible scheme for high-dimensional linear quantum operations on optical transverse spatial modes is demonstrated. The quantum Fourier transformation (QFT) and quantum state tomography (QST) via symmetric informationally complete positive operator-valued measures (SIC POVMs) are implemented with dimensionality of 15. The matrix fidelity of QFT is 0.85, while the statistical fidelity… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.06783v1-abstract-full').style.display = 'inline'; document.getElementById('2005.06783v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2005.06783v1-abstract-full" style="display: none;"> A simple and flexible scheme for high-dimensional linear quantum operations on optical transverse spatial modes is demonstrated. The quantum Fourier transformation (QFT) and quantum state tomography (QST) via symmetric informationally complete positive operator-valued measures (SIC POVMs) are implemented with dimensionality of 15. The matrix fidelity of QFT is 0.85, while the statistical fidelity of SIC POVMs and fidelity of QST are ~0.97 and up to 0.853, respectively. We believe that our device has the potential for further exploration of high-dimensional spatial entanglement provided by spontaneous parametric down conversion in nonlinear crystals. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.06783v1-abstract-full').style.display = 'none'; document.getElementById('2005.06783v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 May, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 14, 024027 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.12097">arXiv:1912.12097</a> <span> [<a href="https://arxiv.org/pdf/1912.12097">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> </div> <p class="title is-5 mathjax"> Ultra-sensitive hybrid diamond nanothermometer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+C">Chu-Feng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Leong%2C+W">Weng-Hang Leong</a>, <a href="/search/quant-ph?searchtype=author&query=Xia%2C+K">Kangwei Xia</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xi Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Finkler%2C+A">Amit Finkler</a>, <a href="/search/quant-ph?searchtype=author&query=Denisenko%2C+A">Andrej Denisenko</a>, <a href="/search/quant-ph?searchtype=author&query=Wrachtrup%2C+J">J枚rg Wrachtrup</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Quan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Ren-Bao 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="1912.12097v1-abstract-short" style="display: inline;"> Nitrogen-vacancy (NV) centers in diamond are promising quantum sensors for their long spin coherence time under ambient conditions. However, their spin resonances are relatively insensitive to non-magnetic parameters such as temperature. A magnetic-nanoparticle-nanodiamond hybrid thermometer, where the temperature change is converted to the magnetic field variation near the Curie temperature, was… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.12097v1-abstract-full').style.display = 'inline'; document.getElementById('1912.12097v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.12097v1-abstract-full" style="display: none;"> Nitrogen-vacancy (NV) centers in diamond are promising quantum sensors for their long spin coherence time under ambient conditions. However, their spin resonances are relatively insensitive to non-magnetic parameters such as temperature. A magnetic-nanoparticle-nanodiamond hybrid thermometer, where the temperature change is converted to the magnetic field variation near the Curie temperature, was demonstrated to have enhanced temperature sensitivity (11 mK Hz^{-1/2}) [Phys. Rev. X 8, 011042 (2018)], but the sensitivity was limited by the large spectral broadening of ensemble spins in nanodiamonds. To overcome this limitation, here we showed an improved design of a hybrid nanothermometer using a single NV center in a diamond nanopillar coupled with a single magnetic nanoparticle of copper-nickel alloy, and demonstrated a temperature sensitivity of 76 uK Hz^{-1/2}. This hybrid design enabled detection of 2 millikelvins temperature changes with temporal resolution of 5 milliseconds. The ultra-sensitive nanothermometer offers a new tool to investigate thermal processes in nanoscale systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.12097v1-abstract-full').style.display = 'none'; document.getElementById('1912.12097v1-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 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </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, 11 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/1910.13743">arXiv:1910.13743</a> <span> [<a href="https://arxiv.org/pdf/1910.13743">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"> An entanglement-based quantum network based on symmetric dispersive optics quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xu Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+X">Xin Yao</a>, <a href="/search/quant-ph?searchtype=author&query=Xue%2C+R">Rong Xue</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Heqing Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei 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="1910.13743v3-abstract-short" style="display: inline;"> Quantum key distribution (QKD) is a crucial technology for information security in the future. Developing simple and efficient ways to establish QKD among multiple users are important to extend the applications of QKD in communication networks. Herein, we proposed a scheme of symmetric dispersive optics QKD (DO-QKD) and demonstrated an entanglement-based quantum network based on it. In the experim… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.13743v3-abstract-full').style.display = 'inline'; document.getElementById('1910.13743v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.13743v3-abstract-full" style="display: none;"> Quantum key distribution (QKD) is a crucial technology for information security in the future. Developing simple and efficient ways to establish QKD among multiple users are important to extend the applications of QKD in communication networks. Herein, we proposed a scheme of symmetric dispersive optics QKD (DO-QKD) and demonstrated an entanglement-based quantum network based on it. In the experiment, a broadband entanglement photon pair source was shared by end users via wavelength and space division multiplexing. The wide spectrum of generated entangled photon pairs was divided into 16 combinations of frequency-conjugate channels. Photon pairs in each channel combination supported a fully-connected subnet with 8 users by a passive beam splitter. Eventually, it showed that an entanglement-based QKD network over 100 users could be supported by one entangled photon pair source in this architecture. It has great potential on applications of local quantum networks with large user number. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.13743v3-abstract-full').style.display = 'none'; document.getElementById('1910.13743v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2019. </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=Feng%2C+X&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a 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