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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=Zhang%2C+Z&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Zhang%2C+Z&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Zhang%2C+Z&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Zhang%2C+Z&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> <li> <a href="/search/?searchtype=author&query=Zhang%2C+Z&start=150" class="pagination-link " aria-label="Page 4" aria-current="page">4 </a> </li> <li> <a href="/search/?searchtype=author&query=Zhang%2C+Z&start=200" class="pagination-link " aria-label="Page 5" aria-current="page">5 </a> </li> <li><span class="pagination-ellipsis">…</span></li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.06127">arXiv:2411.06127</a> <span> [<a href="https://arxiv.org/pdf/2411.06127">pdf</a>, <a href="https://arxiv.org/ps/2411.06127">ps</a>, <a href="https://arxiv.org/format/2411.06127">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="Superconductivity">cond-mat.supr-con</span> </div> </div> <p class="title is-5 mathjax"> Dynamic manifestation of exception points in a non-Hermitian continuous model with an imaginary periodic potential </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y+T">Y. T. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+R">R. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X+Z">X. Z. 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="2411.06127v1-abstract-short" style="display: inline;"> Exceptional points (EPs) are distinct characteristics of non-Hermitian Hamiltonians that have no counterparts in Hermitian systems. In this study, we focus on EPs in continuous systems rather than discrete non-Hermitian systems, which are commonly investigated in both the experimental and theoretical studies. The non-Hermiticity of the system stems from the local imaginary potential, which can be… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06127v1-abstract-full').style.display = 'inline'; document.getElementById('2411.06127v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.06127v1-abstract-full" style="display: none;"> Exceptional points (EPs) are distinct characteristics of non-Hermitian Hamiltonians that have no counterparts in Hermitian systems. In this study, we focus on EPs in continuous systems rather than discrete non-Hermitian systems, which are commonly investigated in both the experimental and theoretical studies. The non-Hermiticity of the system stems from the local imaginary potential, which can be effectively achieved through particle loss in recent quantum simulation setups. Leveraging the discrete Fourier transform, the dynamics of EPs within the low-energy sector can be well modeled by a Stark ladder system under the influence of a non-Hermitian tilted potential. To illustrate this, we systematically investigate continuous systems with finite imaginary potential wells and demonstrate the distinctive EP dynamics across different orders. Our investigation sheds light on EP behaviors, potentially catalyzing further exploration of EP phenomena across a variety of quantum simulation setups. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06127v1-abstract-full').style.display = 'none'; document.getElementById('2411.06127v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.05004">arXiv:2411.05004</a> <span> [<a href="https://arxiv.org/pdf/2411.05004">pdf</a>, <a href="https://arxiv.org/format/2411.05004">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link 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="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Long-range entanglement from spontaneous non-onsite symmetry breaking </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhehao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yabo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+T">Tsung-Cheng Lu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.05004v1-abstract-short" style="display: inline;"> We explore the states of matter arising from the spontaneous symmetry breaking (SSB) of $\mathbb{Z}_2$ non-onsite symmetries. In one spatial dimension, we construct a frustration-free lattice model exhibiting SSB of a non-onsite symmetry, which features the coexistence of two ground states with distinct symmetry-protected topological (SPT) orders. We analytically prove the two-fold ground-state de… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.05004v1-abstract-full').style.display = 'inline'; document.getElementById('2411.05004v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.05004v1-abstract-full" style="display: none;"> We explore the states of matter arising from the spontaneous symmetry breaking (SSB) of $\mathbb{Z}_2$ non-onsite symmetries. In one spatial dimension, we construct a frustration-free lattice model exhibiting SSB of a non-onsite symmetry, which features the coexistence of two ground states with distinct symmetry-protected topological (SPT) orders. We analytically prove the two-fold ground-state degeneracy and the existence of a finite energy gap. Fixing the symmetry sector yields a long-range entangled ground state that features long-range correlations among non-invertible charged operators. We also present a constant-depth measurement-feedback protocol to prepare such a state with a constant success probability in the thermodynamic limit, which may be of independent interest. Under a symmetric deformation, the SSB persists up to a critical point, beyond which a gapless phase characterized by a conformal field theory emerges. In two spatial dimensions, the SSB of 1-form non-onsite symmetries leads to a long-range entangled state (SPT soup) - a condensate of 1d SPT along any closed loops. On a torus, there are four such locally indistinguishable states that exhibit algebraic correlations between local operators, which we derived via a mapping to the critical $O(2)$ loop model. This provides an intriguing example of `topological quantum criticality'. Our work reveals the exotic features of SSB of non-onsite symmetries, which may lie beyond the framework of topological holography (SymTFT). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.05004v1-abstract-full').style.display = 'none'; document.getElementById('2411.05004v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">34 pages, 14 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.21201">arXiv:2410.21201</a> <span> [<a href="https://arxiv.org/pdf/2410.21201">pdf</a>, <a href="https://arxiv.org/ps/2410.21201">ps</a>, <a href="https://arxiv.org/format/2410.21201">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="Computational Complexity">cs.CC</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Data Structures and Algorithms">cs.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> </div> </div> <p class="title is-5 mathjax"> Sample-Optimal Quantum Estimators for Pure-State Trace Distance and Fidelity via Samplizer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qisheng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhicheng 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="2410.21201v1-abstract-short" style="display: inline;"> Trace distance and infidelity (induced by square root fidelity), as basic measures of the closeness of quantum states, are commonly used in quantum state discrimination, certification, and tomography. However, the sample complexity for their estimation still remains open. In this paper, we solve this problem for pure states. We present a quantum algorithm that estimates the trace distance and squa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.21201v1-abstract-full').style.display = 'inline'; document.getElementById('2410.21201v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.21201v1-abstract-full" style="display: none;"> Trace distance and infidelity (induced by square root fidelity), as basic measures of the closeness of quantum states, are commonly used in quantum state discrimination, certification, and tomography. However, the sample complexity for their estimation still remains open. In this paper, we solve this problem for pure states. We present a quantum algorithm that estimates the trace distance and square root fidelity between pure states to within additive error $\varepsilon$, given sample access to their identical copies. Our algorithm achieves the optimal sample complexity $螛(1/\varepsilon^2)$, improving the long-standing folklore $O(1/\varepsilon^4)$. Our algorithm is composed of a samplized phase estimation of the product of two Householder reflections. Notably, an improved (multi-)samplizer for pure states is used as an algorithmic tool in our construction, through which any quantum query algorithm using $Q$ queries to the reflection operator about a pure state $|蠄\rangle$ can be converted to a $未$-close (in the diamond norm) quantum sample algorithm using $螛(Q^2/未)$ samples of $|蠄\rangle$. This samplizer for pure states is shown to be optimal. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.21201v1-abstract-full').style.display = 'none'; document.getElementById('2410.21201v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 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">24 pages, 3 figures, 1 table, 1 algorithm</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.20283">arXiv:2410.20283</a> <span> [<a href="https://arxiv.org/pdf/2410.20283">pdf</a>, <a href="https://arxiv.org/format/2410.20283">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="Optimization and Control">math.OC</span> </div> </div> <p class="title is-5 mathjax"> Efficient Frequency Allocation for Superconducting Quantum Processors Using Improved Optimization Techniques </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zewen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Gokhale%2C+P">Pranav Gokhale</a>, <a href="/search/quant-ph?searchtype=author&query=Larson%2C+J+M">Jeffrey M. Larson</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="2410.20283v1-abstract-short" style="display: inline;"> Building on previous research on frequency allocation optimization for superconducting circuit quantum processors, this work incorporates several new techniques to improve overall solution quality. New features include tightening constraints, imposing edgewise differences, including edge orientation in the optimization, and integrating multimodule designs with various boundary conditions. These en… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.20283v1-abstract-full').style.display = 'inline'; document.getElementById('2410.20283v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.20283v1-abstract-full" style="display: none;"> Building on previous research on frequency allocation optimization for superconducting circuit quantum processors, this work incorporates several new techniques to improve overall solution quality. New features include tightening constraints, imposing edgewise differences, including edge orientation in the optimization, and integrating multimodule designs with various boundary conditions. These enhancements allow for greater flexibility in processor design by eliminating the need for handpicked orientations. We support the efficient assembly of large processors with dense connectivity by choosing the best boundary conditions. Examples demonstrate that, at low computational cost, the new optimization approach finds a frequency configuration for a square chip with over 1,000 qubits and over 10% yield at much larger dispersion levels than required by previous approaches. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.20283v1-abstract-full').style.display = 'none'; document.getElementById('2410.20283v1-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 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/2410.17181">arXiv:2410.17181</a> <span> [<a href="https://arxiv.org/pdf/2410.17181">pdf</a>, <a href="https://arxiv.org/format/2410.17181">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"> Achievable Entanglement-Assisted Communication Rate using Phase-Modulated Two-Mode Squeezed Vacuum </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Su%2C+S">Shang-Jen Su</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Shi-Yuan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Bloch%2C+M+R">Matthieu R. Bloch</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zheshen 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="2410.17181v1-abstract-short" style="display: inline;"> We derive a closed-form achievable rate for entanglement-assisted classical communication over a lossy thermal-noise bosonic channel, where the entanglement is in the form of a Two-Mode Squeezed Vacuum (TMSV) modulation restricted to Phase Shift Keying (PSK). The achievable rate is non-asymptotic in terms of the mean signal photon number, mean noise photon number, and transmissivity defining the c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.17181v1-abstract-full').style.display = 'inline'; document.getElementById('2410.17181v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.17181v1-abstract-full" style="display: none;"> We derive a closed-form achievable rate for entanglement-assisted classical communication over a lossy thermal-noise bosonic channel, where the entanglement is in the form of a Two-Mode Squeezed Vacuum (TMSV) modulation restricted to Phase Shift Keying (PSK). The achievable rate is non-asymptotic in terms of the mean signal photon number, mean noise photon number, and transmissivity defining the communication channel, which provides insights into the interplay of these physical parameters and bridges recent experimental demonstrations of entanglement-assisted communications with the coding theorems used in information-theoretic proofs. The key challenge we address is deriving an analytical bound for the von Neumann entropy of the non-Gaussian mixed state resulting from the phase modulation of one arm of a TMSV. Our approach hinges on two key observations: 1) as the size of the PSK modulation increases, the resulting mixed state converges in trace distance to a diagonal state in the Fock basis; 2) the Fock-basis representation of the diagonal state involves hypergeometric functions that can be appropriately bounded to offer a tractable lower bound for the Holevo information. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.17181v1-abstract-full').style.display = 'none'; document.getElementById('2410.17181v1-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 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/2410.14286">arXiv:2410.14286</a> <span> [<a href="https://arxiv.org/pdf/2410.14286">pdf</a>, <a href="https://arxiv.org/ps/2410.14286">ps</a>, <a href="https://arxiv.org/format/2410.14286">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"> Smolyak algorithm assisted robust control of quantum systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zigui Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Miao%2C+Z">Zibo Miao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+X">Xiu-Hao Deng</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="2410.14286v2-abstract-short" style="display: inline;"> Efficient and systematic numerical methods for robust control design are crucial in quantum systems due to inevitable uncertainties or disturbances. We propose a novel approach that models uncertainties as random variables and quantifies robustness using the expectation of infidelity. By reformulating the robustness measure as a weighted tensor product quadrature, we employ the Smolyak sparse grid… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.14286v2-abstract-full').style.display = 'inline'; document.getElementById('2410.14286v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.14286v2-abstract-full" style="display: none;"> Efficient and systematic numerical methods for robust control design are crucial in quantum systems due to inevitable uncertainties or disturbances. We propose a novel approach that models uncertainties as random variables and quantifies robustness using the expectation of infidelity. By reformulating the robustness measure as a weighted tensor product quadrature, we employ the Smolyak sparse grid algorithm to develop a parametric robust quantum control scheme. This scheme significantly reduces computational cost while improving accuracy. We demonstrate the effectiveness of our Smolyak algorithm assisted gradient-based methods including smGOAT and smGRAPE in robust control problems regarding state transfer and quantum gate realization, with ultrahigh fidelity and strong robustness achieved. Our results contribute to improving the reliability and security of quantum computing and communication systems in the presence of real-world imperfections. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.14286v2-abstract-full').style.display = 'none'; document.getElementById('2410.14286v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 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/2410.12712">arXiv:2410.12712</a> <span> [<a href="https://arxiv.org/pdf/2410.12712">pdf</a>, <a href="https://arxiv.org/format/2410.12712">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="Data Structures and Algorithms">cs.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> </div> </div> <p class="title is-5 mathjax"> On the sample complexity of purity and inner product estimation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gong%2C+W">Weiyuan Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Haferkamp%2C+J">Jonas Haferkamp</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Q">Qi Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhihan 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="2410.12712v1-abstract-short" style="display: inline;"> We study the sample complexity of the prototypical tasks quantum purity estimation and quantum inner product estimation. In purity estimation, we are to estimate $tr(蟻^2)$ of an unknown quantum state $蟻$ to additive error $蔚$. Meanwhile, for quantum inner product estimation, Alice and Bob are to estimate $tr(蟻蟽)$ to additive error $蔚$ given copies of unknown quantum state $蟻$ and $蟽$ using classic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.12712v1-abstract-full').style.display = 'inline'; document.getElementById('2410.12712v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.12712v1-abstract-full" style="display: none;"> We study the sample complexity of the prototypical tasks quantum purity estimation and quantum inner product estimation. In purity estimation, we are to estimate $tr(蟻^2)$ of an unknown quantum state $蟻$ to additive error $蔚$. Meanwhile, for quantum inner product estimation, Alice and Bob are to estimate $tr(蟻蟽)$ to additive error $蔚$ given copies of unknown quantum state $蟻$ and $蟽$ using classical communication and restricted quantum communication. In this paper, we show a strong connection between the sample complexity of purity estimation with bounded quantum memory and inner product estimation with bounded quantum communication and unentangled measurements. We propose a protocol that solves quantum inner product estimation with $k$-qubit one-way quantum communication and unentangled local measurements using $O(median\{1/蔚^2,2^{n/2}/蔚,2^{n-k}/蔚^2\})$ copies of $蟻$ and $蟽$. Our protocol can be modified to estimate the purity of an unknown quantum state $蟻$ using $k$-qubit quantum memory with the same complexity. We prove that arbitrary protocols with $k$-qubit quantum memory that estimate purity to error $蔚$ require $惟(median\{1/蔚^2,2^{n/2}/\sqrt蔚,2^{n-k}/蔚^2\})$ copies of $蟻$. This indicates the same lower bound for quantum inner product estimation with one-way $k$-qubit quantum communication and classical communication, and unentangled local measurements. For purity estimation, we further improve the lower bound to $惟(\max\{1/蔚^2,2^{n/2}/蔚\})$ for any protocols using an identical single-copy projection-valued measurement. Additionally, we investigate a decisional variant of quantum distributed inner product estimation without quantum communication for mixed state and provide a lower bound on the sample complexity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.12712v1-abstract-full').style.display = 'none'; document.getElementById('2410.12712v1-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">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">33 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/2410.09028">arXiv:2410.09028</a> <span> [<a href="https://arxiv.org/pdf/2410.09028">pdf</a>, <a href="https://arxiv.org/format/2410.09028">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Anomalously extended Floquet prethermal lifetimes and applications to long-time quantum sensing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Harkins%2C+K+A">Kieren A. Harkins</a>, <a href="/search/quant-ph?searchtype=author&query=Selco%2C+C">Cooper Selco</a>, <a href="/search/quant-ph?searchtype=author&query=Bengs%2C+C">Christian Bengs</a>, <a href="/search/quant-ph?searchtype=author&query=Marchiori%2C+D">David Marchiori</a>, <a href="/search/quant-ph?searchtype=author&query=Moon%2C+L+J+I">Leo Joon Il Moon</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhuo-Rui Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+A">Aristotle Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Singh%2C+A">Angad Singh</a>, <a href="/search/quant-ph?searchtype=author&query=Druga%2C+E">Emanuel Druga</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yi-Qiao Song</a>, <a href="/search/quant-ph?searchtype=author&query=Ajoy%2C+A">Ashok Ajoy</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="2410.09028v1-abstract-short" style="display: inline;"> Floquet prethermalization is observed in periodically driven quantum many-body systems where the system avoids heating and maintains a stable, non-equilibrium state, for extended periods. Here we introduce a novel quantum control method using off-resonance and short-angle excitation to significantly extend Floquet prethermal lifetimes. This is demonstrated on randomly positioned, dipolar-coupled,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.09028v1-abstract-full').style.display = 'inline'; document.getElementById('2410.09028v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.09028v1-abstract-full" style="display: none;"> Floquet prethermalization is observed in periodically driven quantum many-body systems where the system avoids heating and maintains a stable, non-equilibrium state, for extended periods. Here we introduce a novel quantum control method using off-resonance and short-angle excitation to significantly extend Floquet prethermal lifetimes. This is demonstrated on randomly positioned, dipolar-coupled, 13C nuclear spins in diamond, but the methodology is broadly applicable. We achieve a lifetime $T_2'~800 s at 100 K while tracking the transition to the prethermal state quasi-continuously. This corresponds to a >533,000-fold extension over the bare spin lifetime without prethermalization, and constitutes a new record both in terms of absolute lifetime as well as the total number of Floquet pulses applied (here exceeding 7 million). Using Laplace inversion, we develop a new form of noise spectroscopy that provides insights into the origin of the lifetime extension. Finally, we demonstrate applications of these extended lifetimes in long-time, reinitialization-free quantum sensing of time-varying magnetic fields continuously for ~10 minutes at room temperature. Our work facilitates new opportunities for stabilizing driven quantum systems through Floquet control, and opens novel applications for continuously interrogated, long-time responsive quantum sensors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.09028v1-abstract-full').style.display = 'none'; document.getElementById('2410.09028v1-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, 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">6 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.07544">arXiv:2410.07544</a> <span> [<a href="https://arxiv.org/pdf/2410.07544">pdf</a>, <a href="https://arxiv.org/format/2410.07544">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"> Entanglement-Enhanced Neyman-Pearson Target Detection </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ward%2C+W">William Ward</a>, <a href="/search/quant-ph?searchtype=author&query=Hariri%2C+A">Abdulkarim Hariri</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zheshen 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="2410.07544v1-abstract-short" style="display: inline;"> Quantum illumination (QI) provides entanglement-enabled target-detection enhancement, despite operating in an entanglement-breaking environment. Existing experimental studies of QI have utilized a Bayesian approach, assuming that the target is equally likely to be present or absent before detection, to demonstrate an advantage over classical target detection. However, such a premise breaks down in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.07544v1-abstract-full').style.display = 'inline'; document.getElementById('2410.07544v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.07544v1-abstract-full" style="display: none;"> Quantum illumination (QI) provides entanglement-enabled target-detection enhancement, despite operating in an entanglement-breaking environment. Existing experimental studies of QI have utilized a Bayesian approach, assuming that the target is equally likely to be present or absent before detection, to demonstrate an advantage over classical target detection. However, such a premise breaks down in practical operational scenarios in which the prior probability is unknown, thereby hindering QI's applicability to real-world target-detection scenarios. In this work, we adopt the Neyman-Pearson criterion in lieu of the error probability for equally likely target absence or presence as our figure of merit for QI. We demonstrate an unconditional quantum advantage over the optimal classical-illumination protocol as benchmarked by the receiver operating characteristic, which examines detection probability versus false-alarm probability without resorting to known prior probabilities. Our work represents a critical advancement in adapting quantum-enhanced sensing to practical operational settings. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.07544v1-abstract-full').style.display = 'none'; document.getElementById('2410.07544v1-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 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">12 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.06047">arXiv:2410.06047</a> <span> [<a href="https://arxiv.org/pdf/2410.06047">pdf</a>, <a href="https://arxiv.org/format/2410.06047">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Observation of Higgs and Goldstone modes in U(1) symmetry-broken Rydberg atomic systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Li-Hua Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Ya-Jun Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qi-Feng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yu Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+T">Tian-Yu Han</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zheng-Yuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Shao%2C+S">Shi-Yao Shao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qing Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Han-Chao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Nan%2C+J">Jia-Dou Nan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+D">Dong-Yang Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+Y">Yi-Ming Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+B">Bao-Sen Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+D">Dong-Sheng Ding</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="2410.06047v1-abstract-short" style="display: inline;"> Higgs and Goldstone modes manifest as fluctuations in the order parameter of system, offering insights into its phase transitions and symmetry properties. Exploring the dynamics of these collective excitations in a Rydberg atoms system advances various branches of condensed matter, particle physics, and cosmology. Here, we report an experimental signature of Higgs and Goldstone modes in a U(1) sym… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.06047v1-abstract-full').style.display = 'inline'; document.getElementById('2410.06047v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.06047v1-abstract-full" style="display: none;"> Higgs and Goldstone modes manifest as fluctuations in the order parameter of system, offering insights into its phase transitions and symmetry properties. Exploring the dynamics of these collective excitations in a Rydberg atoms system advances various branches of condensed matter, particle physics, and cosmology. Here, we report an experimental signature of Higgs and Goldstone modes in a U(1) symmetry-broken Rydberg atomic gases. By constructing two probe fields to excite atoms, we observe the distinct phase and amplitude fluctuations of Rydberg atoms collective excitations under the particle-hole symmetry. Due to the van der Waals interactions between the Rydberg atoms, we detect a symmetric variance spectrum divided by the divergent regime and phase boundary, capturing the full dynamics of the additional Higgs and Goldstone modes. Studying the Higgs and Goldstone modes in Rydberg atoms allows us to explore fundamental aspects of quantum phase transitions and symmetry breaking phenomena, while leveraging the unique properties of these highly interacting systems to uncover new physics and potential applications in quantum simulation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.06047v1-abstract-full').style.display = 'none'; document.getElementById('2410.06047v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 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/2410.05625">arXiv:2410.05625</a> <span> [<a href="https://arxiv.org/pdf/2410.05625">pdf</a>, <a href="https://arxiv.org/format/2410.05625">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> </div> <p class="title is-5 mathjax"> Discrete Time Crystal Sensing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Moon%2C+L+J+I">Leo Joon Il Moon</a>, <a href="/search/quant-ph?searchtype=author&query=Schindler%2C+P+M">Paul M. Schindler</a>, <a href="/search/quant-ph?searchtype=author&query=Smith%2C+R+J">Ryan J. Smith</a>, <a href="/search/quant-ph?searchtype=author&query=Druga%2C+E">Emanuel Druga</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhuo-Rui Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Bukov%2C+M">Marin Bukov</a>, <a href="/search/quant-ph?searchtype=author&query=Ajoy%2C+A">Ashok Ajoy</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="2410.05625v1-abstract-short" style="display: inline;"> Prethermal discrete time crystals (PDTCs) are a nonequilibrium state of matter characterized by long-range spatiotemporal order, and exhibiting a subharmonic response stabilized by many-body interactions under periodic driving. The inherent robustness of time crystalline order to perturbations in the drive protocol makes DTCs promising for applications in quantum technologies. We exploit the susce… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.05625v1-abstract-full').style.display = 'inline'; document.getElementById('2410.05625v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.05625v1-abstract-full" style="display: none;"> Prethermal discrete time crystals (PDTCs) are a nonequilibrium state of matter characterized by long-range spatiotemporal order, and exhibiting a subharmonic response stabilized by many-body interactions under periodic driving. The inherent robustness of time crystalline order to perturbations in the drive protocol makes DTCs promising for applications in quantum technologies. We exploit the susceptibility of PDTC order to deviations in its order parameter to devise highly frequency-selective quantum sensors for time-varying (AC) magnetic fields in a system of strongly-driven, dipolar-coupled 13C nuclear spins in diamond. Integrating a time-varying AC field into the PDTC allows us to exponentially increase its lifetime, measuring improvement of up to three orders of magnitude (44,204 cycles), and results in a strong resonant response in the time crystalline order parameter. The linewidth of our sensor is limited by the PDTC lifetime alone, as strong interspin interactions help stabilize DTC order. The sensor operates in the 0.5-50 kHz range - a blind spot for sensors based on atomic vapor or electronic spins - and attains a competitive sensitivity. PDTC sensors are resilient to errors in the drive protocol and sample inhomogeneities, and are agnostic to the macroscopic details of the physical platform: the underlying physical principle applies equally to superconducting qubits, neutral atoms, and trapped ions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.05625v1-abstract-full').style.display = 'none'; document.getElementById('2410.05625v1-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 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">7+16 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/2410.03906">arXiv:2410.03906</a> <span> [<a href="https://arxiv.org/pdf/2410.03906">pdf</a>, <a href="https://arxiv.org/format/2410.03906">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mathematical Physics">math-ph</span> </div> </div> <p class="title is-5 mathjax"> Efficient self-consistent learning of gate set Pauli noise </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Senrui Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhihan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Flammia%2C+S+T">Steven T. Flammia</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="2410.03906v1-abstract-short" style="display: inline;"> Understanding quantum noise is an essential step towards building practical quantum information processing systems. Pauli noise is a useful model that has been widely applied in quantum benchmarking, error mitigation, and error correction. Despite intensive study, most existing works focus on learning Pauli noise channels associated with some specific gates rather than treating the gate set as a w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.03906v1-abstract-full').style.display = 'inline'; document.getElementById('2410.03906v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.03906v1-abstract-full" style="display: none;"> Understanding quantum noise is an essential step towards building practical quantum information processing systems. Pauli noise is a useful model that has been widely applied in quantum benchmarking, error mitigation, and error correction. Despite intensive study, most existing works focus on learning Pauli noise channels associated with some specific gates rather than treating the gate set as a whole. A learning algorithm that is self-consistent, complete, and efficient at the same time is yet to be established. In this work, we study the task of gate set Pauli noise learning, where a set of quantum gates, state preparation, and measurements all suffer from unknown Pauli noise channels with a customized noise ansatz. Using tools from algebraic graph theory, we analytically characterize the self-consistently learnable degrees of freedom for Pauli noise models with arbitrary linear ansatz, and design experiments to efficiently learn all the learnable information. Specifically, we show that all learnable information about the gate noise can be learned to relative precision, under mild assumptions on the noise ansatz. We then demonstrate the flexibility of our theory by applying it to concrete physically motivated ansatzs (such as spatially local or quasi-local noise) and experimentally relevant gate sets (such as parallel CZ gates). These results not only enhance the theoretical understanding of quantum noise learning, but also provide a feasible recipe for characterizing existing and near-future quantum information processing devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.03906v1-abstract-full').style.display = 'none'; document.getElementById('2410.03906v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 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">44 + 12 pages, 14 figures, comments welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.02452">arXiv:2410.02452</a> <span> [<a href="https://arxiv.org/pdf/2410.02452">pdf</a>, <a href="https://arxiv.org/format/2410.02452">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Motion-Insensitive Time-Optimal Control of Optical Qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Van+Damme%2C+L">L茅o Van Damme</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Devra%2C+A">Amit Devra</a>, <a href="/search/quant-ph?searchtype=author&query=Glaser%2C+S+J">Steffen J. Glaser</a>, <a href="/search/quant-ph?searchtype=author&query=Alberti%2C+A">Andrea Alberti</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="2410.02452v1-abstract-short" style="display: inline;"> In trapped-atom quantum computers, high-fidelity control of optical qubits is challenging due to the motion of atoms in the trap. If not corrected, the atom motion gets entangled with the qubit degrees of freedom through two fundamental mechanisms, (i) photon recoil and (ii) thermal motion, both leading to a reduction of the gate fidelity. We develop motion-insensitive pulses that suppress both so… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.02452v1-abstract-full').style.display = 'inline'; document.getElementById('2410.02452v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.02452v1-abstract-full" style="display: none;"> In trapped-atom quantum computers, high-fidelity control of optical qubits is challenging due to the motion of atoms in the trap. If not corrected, the atom motion gets entangled with the qubit degrees of freedom through two fundamental mechanisms, (i) photon recoil and (ii) thermal motion, both leading to a reduction of the gate fidelity. We develop motion-insensitive pulses that suppress both sources of infidelity by modulating the phase of the driving laser field in time. To eliminate photon recoil, we use bang-bang pulses$-$derived using time-optimal control$-$which shorten the gate duration by about 20 times compared to conventional pulses. However, even when photon recoil is eliminated, we find that the gate error does not vanish, but is rather limited by a bound arising from thermal motion-induced entanglement. Remarkably, this bound is independent of the Rabi frequency, meaning that, unlike for photon recoil, operating in the resolved sideband regime does not mitigate this source of infidelity. To overcome this bound, we derive smooth-phase pulses, which allow for a further reduction of the gate error by more than an order of magnitude for typical thermal atoms. Motion-insensitive pulses can be refined to compensate for laser inhomogeneities, enhancing the gate performance in practical situations. Our results are validated through simulations of one-qubit gates operating on the optical clock transition of ${}^{88}$Sr atoms trapped in an optical tweezers array. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.02452v1-abstract-full').style.display = 'none'; document.getElementById('2410.02452v1-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 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">22 pages, 10 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">MSC Class:</span> 81Q93 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.19699">arXiv:2409.19699</a> <span> [<a href="https://arxiv.org/pdf/2409.19699">pdf</a>, <a href="https://arxiv.org/format/2409.19699">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mathematical Physics">math-ph</span> </div> </div> <p class="title is-5 mathjax"> Efficient Verification of Stabilizer Code Subspaces with Local Measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+C">Congcong Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+X">Xutao Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zaichen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+P">Ping Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+K">Kun 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="2409.19699v1-abstract-short" style="display: inline;"> We address the task of verifying whether a quantum computer, designed to be protected by a specific stabilizer code, correctly encodes the corresponding logical qubits. To achieve this, we develop a general framework for subspace verification and explore several stabilizer code subspaces of practical significance. First, we present two efficient verification strategies for general stabilizer code… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.19699v1-abstract-full').style.display = 'inline'; document.getElementById('2409.19699v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.19699v1-abstract-full" style="display: none;"> We address the task of verifying whether a quantum computer, designed to be protected by a specific stabilizer code, correctly encodes the corresponding logical qubits. To achieve this, we develop a general framework for subspace verification and explore several stabilizer code subspaces of practical significance. First, we present two efficient verification strategies for general stabilizer code subspaces, utilizing measurements of their stabilizer generators and stabilizer groups, respectively. Then, building on the observation that certain tests can be conducted in parallel when the subspace exhibits specific structural properties, we propose a coloring strategy tailored to graph code subspaces and an XZ strategy tailored to Calderbank-Shor-Steane (CSS) code subspaces. Compared to stabilizer-based strategies, these new strategies require significantly fewer measurement settings and consume fewer state copies, approaching near-global optimality. Notably, all the strategies employ a limited number of Pauli measurements, are non-adaptive, and work on mixed states, enabling efficient experimental certification of both logical qubits and logical operations in noisy quantum computers. This work contributes to the first systematic study of efficient verification of stabilizer code subspaces with local measurements. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.19699v1-abstract-full').style.display = 'none'; document.getElementById('2409.19699v1-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Comments are welcome!</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.11035">arXiv:2409.11035</a> <span> [<a href="https://arxiv.org/pdf/2409.11035">pdf</a>, <a href="https://arxiv.org/format/2409.11035">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Dynamical topological phase transition in cold Rydberg quantum gases </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Ya-Jun Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Li-Hua Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zheng-Yuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Shao%2C+S">Shi-Yao Shao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qing Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Han-Chao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yu Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+T">Tian-Yu Han</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qi-Feng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Nan%2C+J">Jia-Dou Nan</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+Y">Yi-Ming Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+D">Dong-Yang Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+B">Bao-Sen Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+D">Dong-Sheng Ding</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.11035v1-abstract-short" style="display: inline;"> Study of phase transitions provide insights into how a many-body system behaves under different conditions, enabling us to understand the symmetry breaking, critical phenomena, and topological properties. Strong long-range interactions in highly excited Rydberg atoms create a versatile platform for exploring exotic emergent topological phases. Here, we report the experimental observation of dynami… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.11035v1-abstract-full').style.display = 'inline'; document.getElementById('2409.11035v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.11035v1-abstract-full" style="display: none;"> Study of phase transitions provide insights into how a many-body system behaves under different conditions, enabling us to understand the symmetry breaking, critical phenomena, and topological properties. Strong long-range interactions in highly excited Rydberg atoms create a versatile platform for exploring exotic emergent topological phases. Here, we report the experimental observation of dynamical topological phase transitions in cold Rydberg atomic gases under a microwave field driving. By measuring the system transmission curves while varying the probe intensity, we observe complex hysteresis trajectories characterized by distinct winding numbers as they cross the critical point. At the transition state, where the winding number flips, the topology of these hysteresis trajectories evolves into more non-trivial structures. The topological trajectories are shown to be robust against noise, confirming their rigidity in dynamic conditions. These findings contribute to the insights of emergence of complex dynamical topological phases in many-body systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.11035v1-abstract-full').style.display = 'none'; document.getElementById('2409.11035v1-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.10626">arXiv:2409.10626</a> <span> [<a href="https://arxiv.org/pdf/2409.10626">pdf</a>, <a href="https://arxiv.org/format/2409.10626">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> </div> <p class="title is-5 mathjax"> Observation of Interface Piezoelectricity in Superconducting Devices on Silicon </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+H">Haoxin Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+E">Eric Li</a>, <a href="/search/quant-ph?searchtype=author&query=Godeneli%2C+K">Kadircan Godeneli</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zi-Huai Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jahanbani%2C+S">Shahin Jahanbani</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+K">Kangdi Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Odeh%2C+M">Mutasem Odeh</a>, <a href="/search/quant-ph?searchtype=author&query=Aloni%2C+S">Shaul Aloni</a>, <a href="/search/quant-ph?searchtype=author&query=Griffin%2C+S">Sin茅ad Griffin</a>, <a href="/search/quant-ph?searchtype=author&query=Sipahigil%2C+A">Alp Sipahigil</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.10626v1-abstract-short" style="display: inline;"> The evolution of superconducting quantum processors is driven by the need to reduce errors and scale for fault-tolerant computation. Reducing physical qubit error rates requires further advances in the microscopic modeling and control of decoherence mechanisms in superconducting qubits. Piezoelectric interactions contribute to decoherence by mediating energy exchange between microwave photons and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.10626v1-abstract-full').style.display = 'inline'; document.getElementById('2409.10626v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.10626v1-abstract-full" style="display: none;"> The evolution of superconducting quantum processors is driven by the need to reduce errors and scale for fault-tolerant computation. Reducing physical qubit error rates requires further advances in the microscopic modeling and control of decoherence mechanisms in superconducting qubits. Piezoelectric interactions contribute to decoherence by mediating energy exchange between microwave photons and acoustic phonons. Centrosymmetric materials like silicon and sapphire do not display piezoelectricity and are the preferred substrates for superconducting qubits. However, the broken centrosymmetry at material interfaces may lead to piezoelectric losses in qubits. While this loss mechanism was predicted two decades ago, interface piezoelectricity has not been experimentally observed in superconducting devices. Here, we report the observation of interface piezoelectricity at an aluminum-silicon junction and show that it constitutes an important loss channel for superconducting devices. We fabricate aluminum interdigital surface acoustic wave transducers on silicon and demonstrate piezoelectric transduction from room temperature to millikelvin temperatures. We find an effective electromechanical coupling factor of $K^2\approx 2 \times 10^{-5}\%$ comparable to weakly piezoelectric substrates. We model the impact of the measured interface piezoelectric response on superconducting qubits and find that the piezoelectric surface loss channel limits qubit quality factors to $Q\sim10^4-10^8$ for designs with different surface participation ratios and electromechanical mode matching. These results identify electromechanical surface losses as a significant dissipation channel for superconducting qubits, and show the need for heterostructure and phononic engineering to minimize errors in next-generation superconducting qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.10626v1-abstract-full').style.display = 'none'; document.getElementById('2409.10626v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.01862">arXiv:2409.01862</a> <span> [<a href="https://arxiv.org/pdf/2409.01862">pdf</a>, <a href="https://arxiv.org/format/2409.01862">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> On-the-Fly Ab Initio Hagedorn Wavepacket Dynamics: Single Vibronic Level Fluorescence Spectra of Difluorocarbene </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z+T">Zhan Tong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Visegr%C3%A1di%2C+M">M谩t茅 Visegr谩di</a>, <a href="/search/quant-ph?searchtype=author&query=Van%C3%AD%C4%8Dek%2C+J+J+L">Ji艡铆 J. L. Van铆膷ek</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.01862v1-abstract-short" style="display: inline;"> Hagedorn wavepackets have been used with local harmonic approximation to partially capture the anharmonic effects on single vibronic level (SVL) spectra in model potentials. To make the Hagedorn approach practical for realistic anharmonic polyatomic molecules, here we combine local harmonic Hagedorn wavepacket dynamics with on-the-fly ab initio dynamics. We then test this method by computing the S… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.01862v1-abstract-full').style.display = 'inline'; document.getElementById('2409.01862v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.01862v1-abstract-full" style="display: none;"> Hagedorn wavepackets have been used with local harmonic approximation to partially capture the anharmonic effects on single vibronic level (SVL) spectra in model potentials. To make the Hagedorn approach practical for realistic anharmonic polyatomic molecules, here we combine local harmonic Hagedorn wavepacket dynamics with on-the-fly ab initio dynamics. We then test this method by computing the SVL fluorescence spectra of difluorocarbene, a small, floppy molecule with a very anharmonic potential energy surface. Our time-dependent approach obtains the emission spectra of all initial vibrational levels from a single anharmonic semiclassical wavepacket trajectory without the need to fit individual anharmonic vibrational wavefunctions and to calculate the Franck--Condon factors for all vibronic transitions. We show that, whereas global harmonic models are inadequate for CF$_2$, the spectra computed with the on-the-fly local harmonic Hagedorn wavepacket dynamics agree well with experimental data, especially for low initial excitations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.01862v1-abstract-full').style.display = 'none'; document.getElementById('2409.01862v1-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.13817">arXiv:2408.13817</a> <span> [<a href="https://arxiv.org/pdf/2408.13817">pdf</a>, <a href="https://arxiv.org/format/2408.13817">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum-enhanced weak absorption estimation with correlated photons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhucheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xue Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jing Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+H">Hui Dong</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="2408.13817v1-abstract-short" style="display: inline;"> Absorption estimation, the base of spectroscopy, is crucial for probing the composition and dynamics of matter. Conventional methods of estimation rely on coherent laser sources, and in turn suffer from inherent limitations in estimating weak absorption. Here we propose a new measurement strategy with correlated photons to determine the weak absorption by distinguishing the output with and without… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13817v1-abstract-full').style.display = 'inline'; document.getElementById('2408.13817v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.13817v1-abstract-full" style="display: none;"> Absorption estimation, the base of spectroscopy, is crucial for probing the composition and dynamics of matter. Conventional methods of estimation rely on coherent laser sources, and in turn suffer from inherent limitations in estimating weak absorption. Here we propose a new measurement strategy with correlated photons to determine the weak absorption by distinguishing the output with and without photons, dubbed as the on-off measurement. Our implementation within the strategy allows the estimation precision to reach the ultimate quantum limit. We demonstrate that absorption spectroscopy that incorporates quantum correlations is capable of estimating weak absorption down to a single-photon level, even in noisy environments, achieving a precision comparable to that obtained through several hundred photons in conventional absorption spectroscopy. By introducing the quantum correlations, our work avoids the occurrence of light-induced damage while breaking the classical inherent limitations in spectroscopy. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13817v1-abstract-full').style.display = 'none'; document.getElementById('2408.13817v1-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, 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">7 pages, 3 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.11991">arXiv:2408.11991</a> <span> [<a href="https://arxiv.org/pdf/2408.11991">pdf</a>, <a href="https://arxiv.org/format/2408.11991">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> <p class="title is-5 mathjax"> Capturing anharmonic effects in single vibronic level fluorescence spectra using local harmonic Hagedorn wavepacket dynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z+T">Zhan Tong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Visegr%C3%A1di%2C+M">M谩t茅 Visegr谩di</a>, <a href="/search/quant-ph?searchtype=author&query=Van%C3%AD%C4%8Dek%2C+J+J+L">Ji艡铆 J. L. Van铆膷ek</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="2408.11991v1-abstract-short" style="display: inline;"> Hagedorn wavepacket dynamics yields exact single vibronic level (SVL) fluorescence spectra from any initial vibrational level in displaced, squeezed, and Duschinsky-rotated global harmonic models. Real molecules, however, have anharmonic potential energy surfaces. To partially describe effects of anharmonicity on the spectra, we combine the Hagedorn approach to spectroscopy with the local harmonic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.11991v1-abstract-full').style.display = 'inline'; document.getElementById('2408.11991v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.11991v1-abstract-full" style="display: none;"> Hagedorn wavepacket dynamics yields exact single vibronic level (SVL) fluorescence spectra from any initial vibrational level in displaced, squeezed, and Duschinsky-rotated global harmonic models. Real molecules, however, have anharmonic potential energy surfaces. To partially describe effects of anharmonicity on the spectra, we combine the Hagedorn approach to spectroscopy with the local harmonic approximation of the potential. We compute the SVL spectra for several anharmonic Morse-type potentials in one, two, and twenty dimensions and compare them to the results of global harmonic approximations and, where possible, of exact quantum calculations. We show that the local harmonic approach yields more accurate results than global harmonic approximations, especially for the emission spectra from higher initial vibrational levels. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.11991v1-abstract-full').style.display = 'none'; document.getElementById('2408.11991v1-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 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">7 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.11226">arXiv:2408.11226</a> <span> [<a href="https://arxiv.org/pdf/2408.11226">pdf</a>, <a href="https://arxiv.org/format/2408.11226">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"> Optimizing Quantum Fourier Transformation (QFT) Kernels for Modern NISQ and FT Architectures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Jin%2C+Y">Yuwei Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+X">Xiangyu Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+M">Minghao Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Henry Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+F">Fei Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+E+Z">Eddy Z. 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="2408.11226v1-abstract-short" style="display: inline;"> Rapid development in quantum computing leads to the appearance of several quantum applications. Quantum Fourier Transformation (QFT) sits at the heart of many of these applications. Existing work leverages SAT solver or heuristics to generate a hardware-compliant circuit for QFT by inserting SWAP gates to remap logical qubits to physical qubits. However, they might face problems such as long compi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.11226v1-abstract-full').style.display = 'inline'; document.getElementById('2408.11226v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.11226v1-abstract-full" style="display: none;"> Rapid development in quantum computing leads to the appearance of several quantum applications. Quantum Fourier Transformation (QFT) sits at the heart of many of these applications. Existing work leverages SAT solver or heuristics to generate a hardware-compliant circuit for QFT by inserting SWAP gates to remap logical qubits to physical qubits. However, they might face problems such as long compilation time due to the huge search space for SAT solver or suboptimal outcome in terms of the number of cycles to finish all gate operations. In this paper, we propose a domain-specific hardware mapping approach for QFT. We unify our insight of relaxed ordering and unit exploration in QFT to search for a qubit mapping solution with the help of program synthesis tools. Our method is the first one that guarantees linear-depth QFT circuits for Google Sycamore, IBM heavy-hex, and the lattice surgery, with respect to the number of qubits. Compared with state-of-the-art approaches, our method can save up to 53% in SWAP gate and 92% in depth. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.11226v1-abstract-full').style.display = 'none'; document.getElementById('2408.11226v1-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 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">arXiv admin note: text overlap with arXiv:2312.16114</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.10514">arXiv:2408.10514</a> <span> [<a href="https://arxiv.org/pdf/2408.10514">pdf</a>, <a href="https://arxiv.org/format/2408.10514">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Folded multistability and hidden critical point in microwave-driven Rydberg atoms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yu Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Li-Hua Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Ya-Jun Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zheng-Yuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Shao%2C+S">Shi-Yao Shao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qing Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Han-Chao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+T">Tian-Yu Han</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qi-Feng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Nan%2C+J">Jia-Dou Nan</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+Y">Yi-Ming Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+D">Dong-Yang Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+B">Bao-Sen Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+D">Dong-Sheng Ding</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="2408.10514v2-abstract-short" style="display: inline;"> The interactions between Rydberg atoms and microwave fields provide a valuable framework for studying the complex dynamics out of equilibrium, exotic phases, and critical phenomena in many-body physics. This unique interplay allows us to explore various regimes of nonlinearity and phase transitions. Here, we observe a phase transition from the state in the regime of bistability to that in multista… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.10514v2-abstract-full').style.display = 'inline'; document.getElementById('2408.10514v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.10514v2-abstract-full" style="display: none;"> The interactions between Rydberg atoms and microwave fields provide a valuable framework for studying the complex dynamics out of equilibrium, exotic phases, and critical phenomena in many-body physics. This unique interplay allows us to explore various regimes of nonlinearity and phase transitions. Here, we observe a phase transition from the state in the regime of bistability to that in multistability in strongly interacting Rydberg atoms by varying the microwave field intensity, accompanying with the breaking of Z3-symmetry. During the phase transition, the system experiences a hidden critical point, in which the multistable states are difficult to be identified. Through changing the initial state of system, we can identify a hidden multistable state and reveal a hidden trajectory of phase transition, allowing us to track to a hidden critical point. In addition, we observe multiple phase transitions in spectra, suggesting higher-order symmetry breaking. The reported results shed light on manipulating multistability in dissipative Rydberg atoms systems and hold promise in the applications of non-equilibrium many-body physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.10514v2-abstract-full').style.display = 'none'; document.getElementById('2408.10514v2-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 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">10 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.10054">arXiv:2408.10054</a> <span> [<a href="https://arxiv.org/pdf/2408.10054">pdf</a>, <a href="https://arxiv.org/format/2408.10054">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="Hardware Architecture">cs.AR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Programming Languages">cs.PL</span> </div> </div> <p class="title is-5 mathjax"> Quantum Register Machine: Efficient Implementation of Quantum Recursive Programs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhicheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</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="2408.10054v2-abstract-short" style="display: inline;"> Quantum recursive programming has been recently introduced for describing sophisticated and complicated quantum algorithms in a compact and elegant way. However, implementation of quantum recursion involves intricate interplay between quantum control flows and recursive procedure calls. In this paper, we aim at resolving this fundamental challenge and develop a series of techniques to efficiently… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.10054v2-abstract-full').style.display = 'inline'; document.getElementById('2408.10054v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.10054v2-abstract-full" style="display: none;"> Quantum recursive programming has been recently introduced for describing sophisticated and complicated quantum algorithms in a compact and elegant way. However, implementation of quantum recursion involves intricate interplay between quantum control flows and recursive procedure calls. In this paper, we aim at resolving this fundamental challenge and develop a series of techniques to efficiently implement quantum recursive programs. Our main contributions include: 1. We propose a notion of quantum register machine, the first purely quantum architecture (including an instruction set) that supports quantum control flows and recursive procedure calls at the same time. 2. Based on quantum register machine, we describe the first comprehensive implementation process of quantum recursive programs, including the compilation, the partial evaluation of quantum control flows, and the execution on the quantum register machine. 3. As a bonus, our efficient implementation of quantum recursive programs also offers automatic parallelisation of quantum algorithms. For implementing certain quantum algorithmic subroutine, like the widely used quantum multiplexor, we can even obtain exponential parallel speed-up (over the straightforward implementation) from this automatic parallelisation. This demonstrates that quantum recursive programming can be win-win for both modularity of programs and efficiency of their implementation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.10054v2-abstract-full').style.display = 'none'; document.getElementById('2408.10054v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 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">Minor revision. 72 pages, 26 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.08415">arXiv:2408.08415</a> <span> [<a href="https://arxiv.org/pdf/2408.08415">pdf</a>, <a href="https://arxiv.org/format/2408.08415">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Dynamics of the unitary Bose gas near a narrow Feshbach resonance: universal coherent atom-molecule oscillations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+K">Ke Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhendong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Nagata%2C+S">Shu Nagata</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhiqiang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Levin%2C+K">K. Levin</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="2408.08415v1-abstract-short" style="display: inline;"> Quench experiments on a unitary Bose gas around a broad Feshbach resonance have led to the discovery of universal dynamics. This universality is manifested in the measured atomic momentum distributions where, asymptotically, a quasi-equilibrated metastable state is found in which both the momentum distribution and the time scales are determined by the particle density. In this paper we present cou… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08415v1-abstract-full').style.display = 'inline'; document.getElementById('2408.08415v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.08415v1-abstract-full" style="display: none;"> Quench experiments on a unitary Bose gas around a broad Feshbach resonance have led to the discovery of universal dynamics. This universality is manifested in the measured atomic momentum distributions where, asymptotically, a quasi-equilibrated metastable state is found in which both the momentum distribution and the time scales are determined by the particle density. In this paper we present counterpart studies but for the case of a very narrow Feshbach resonance of $^{133}$Cs atoms having a width of 8.3 mG. In dramatic contrast to the behavior reported earlier, a rapid quench of an atomic condensate to unitarity is observed to ultimately lead to coherent oscillations involving dynamically produced condensed and non-condensed molecules and atoms. The same characteristic frequency, determined by the Feshbach coupling, is observed in all types of particles. To understand these quench dynamics and how these different particle species are created, we develop a beyond Hartree-Fock-Bogoliubov dynamical framework including a new type of cross correlation between atoms and molecules. This leads to a quantitative consistency with the measured frequency. Our results, which can be applied to the general class of bosonic superfluids associated with narrow Feshbach resonances, establish a new paradigm for universal dynamics dominated by quantum many-body interactions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08415v1-abstract-full').style.display = 'none'; document.getElementById('2408.08415v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 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">11 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.07342">arXiv:2408.07342</a> <span> [<a href="https://arxiv.org/pdf/2408.07342">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Evidence of P-wave Pairing in K2Cr3As3 Superconductors from Phase-sensitive Measurement </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhiyuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Dou%2C+Z">Ziwei Dou</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+A">Anqi Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Cuiwei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+Y">Yu Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Lei%2C+X">Xincheng Lei</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+Y">Yue Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Z">Zhongchen Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Z">Zhipeng Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yupeng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+G">Guoan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+X">Xiaofan Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+X">Xingchen Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+X">Xiao Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Lyu%2C+Z">Zhaozheng Lyu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+P">Peiling Li</a>, <a href="/search/quant-ph?searchtype=author&query=Qu%2C+F">Faming Qu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Guangtong Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+D">Dong Su</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+K">Kun Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+Y">Youguo Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+L">Li Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+J">Jie Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+J">Jiangping Hu</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="2408.07342v1-abstract-short" style="display: inline;"> P-wave superconductors hold immense promise for both fundamental physics and practical applications due to their unusual pairing symmetry and potential topological superconductivity. However, the exploration of the p-wave superconductors has proved to be a complex endeavor. Not only are they rare in nature but also the identification of p-wave superconductors has been an arduous task in history. F… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.07342v1-abstract-full').style.display = 'inline'; document.getElementById('2408.07342v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.07342v1-abstract-full" style="display: none;"> P-wave superconductors hold immense promise for both fundamental physics and practical applications due to their unusual pairing symmetry and potential topological superconductivity. However, the exploration of the p-wave superconductors has proved to be a complex endeavor. Not only are they rare in nature but also the identification of p-wave superconductors has been an arduous task in history. For example, phase-sensitive measurement, an experimental technique which can provide conclusive evidence for unconventional pairing, has not been implemented successfully to identify p-wave superconductors. Here, we study a recently discovered family of superconductors, A2Cr3As3 (A = K, Rb, Cs), which were proposed theoretically to be a candidate of p-wave superconductors. We fabricate superconducting quantum interference devices (SQUIDs) on exfoliated K2Cr3As3, and perform the phase-sensitive measurement. We observe that such SQUIDs exhibit a pronounced second-order harmonic component sin(2蠁) in the current-phase relation, suggesting the admixture of 0- and 蟺-phase. By carefully examining the magnetic field dependence of the oscillation patterns of critical current and Shapiro steps under microwave irradiation, we reveal a crossover from 0- to 蟺-dominating phase state and conclude that the existence of the 蟺-phase is in favor of the p-wave pairing symmetry in K2Cr3As3. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.07342v1-abstract-full').style.display = 'none'; document.getElementById('2408.07342v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.06967">arXiv:2408.06967</a> <span> [<a href="https://arxiv.org/pdf/2408.06967">pdf</a>, <a href="https://arxiv.org/ps/2408.06967">ps</a>, <a href="https://arxiv.org/format/2408.06967">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="Computational Complexity">cs.CC</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Data Structures and Algorithms">cs.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> </div> </div> <p class="title is-5 mathjax"> Stabilizer bootstrapping: A recipe for efficient agnostic tomography and magic estimation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Sitan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+W">Weiyuan Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Q">Qi Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhihan 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="2408.06967v2-abstract-short" style="display: inline;"> We study the task of agnostic tomography: given copies of an unknown $n$-qubit state $蟻$ which has fidelity $蟿$ with some state in a given class $C$, find a state which has fidelity $\ge 蟿- 蔚$ with $蟻$. We give a new framework, stabilizer bootstrapping, for designing computationally efficient protocols for this task, and use this to get new agnostic tomography protocols for the following classes:… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.06967v2-abstract-full').style.display = 'inline'; document.getElementById('2408.06967v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.06967v2-abstract-full" style="display: none;"> We study the task of agnostic tomography: given copies of an unknown $n$-qubit state $蟻$ which has fidelity $蟿$ with some state in a given class $C$, find a state which has fidelity $\ge 蟿- 蔚$ with $蟻$. We give a new framework, stabilizer bootstrapping, for designing computationally efficient protocols for this task, and use this to get new agnostic tomography protocols for the following classes: Stabilizer states: We give a protocol that runs in time $\mathrm{poly}(n,1/蔚)\cdot (1/蟿)^{O(\log(1/蟿))}$, answering an open question posed by Grewal, Iyer, Kretschmer, Liang [43] and Anshu and Arunachalam [6]. Previous protocols ran in time $\mathrm{exp}(螛(n))$ or required $蟿>\cos^2(蟺/8)$. States with stabilizer dimension $n - t$: We give a protocol that runs in time $n^3\cdot(2^t/蟿)^{O(\log(1/蔚))}$, extending recent work on learning quantum states prepared by circuits with few non-Clifford gates, which only applied in the realizable setting where $蟿= 1$ [33, 40, 49, 66]. Discrete product states: If $C = K^{\otimes n}$ for some $渭$-separated discrete set $K$ of single-qubit states, we give a protocol that runs in time $(n/渭)^{O((1 + \log (1/蟿))/渭)}/蔚^2$. This strictly generalizes a prior guarantee which applied to stabilizer product states [42]. For stabilizer product states, we give a further improved protocol that runs in time $(n^2/蔚^2)\cdot (1/蟿)^{O(\log(1/蟿))}$. As a corollary, we give the first protocol for estimating stabilizer fidelity, a standard measure of magic for quantum states, to error $蔚$ in $n^3 \mathrm{quasipoly}(1/蔚)$ time. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.06967v2-abstract-full').style.display = 'none'; document.getElementById('2408.06967v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 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">68 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/2408.04622">arXiv:2408.04622</a> <span> [<a href="https://arxiv.org/pdf/2408.04622">pdf</a>, <a href="https://arxiv.org/format/2408.04622">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Recoil-free Quantum Gates with Optical Qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Van+Damme%2C+L">L茅o Van Damme</a>, <a href="/search/quant-ph?searchtype=author&query=Rossignolo%2C+M">Marco Rossignolo</a>, <a href="/search/quant-ph?searchtype=author&query=Festa%2C+L">Lorenzo Festa</a>, <a href="/search/quant-ph?searchtype=author&query=Melchner%2C+M">Max Melchner</a>, <a href="/search/quant-ph?searchtype=author&query=Eberhard%2C+R">Robin Eberhard</a>, <a href="/search/quant-ph?searchtype=author&query=Tsevas%2C+D">Dimitrios Tsevas</a>, <a href="/search/quant-ph?searchtype=author&query=Mours%2C+K">Kevin Mours</a>, <a href="/search/quant-ph?searchtype=author&query=Reches%2C+E">Eran Reches</a>, <a href="/search/quant-ph?searchtype=author&query=Zeiher%2C+J">Johannes Zeiher</a>, <a href="/search/quant-ph?searchtype=author&query=Blatt%2C+S">Sebastian Blatt</a>, <a href="/search/quant-ph?searchtype=author&query=Bloch%2C+I">Immanuel Bloch</a>, <a href="/search/quant-ph?searchtype=author&query=Glaser%2C+S+J">Steffen J. Glaser</a>, <a href="/search/quant-ph?searchtype=author&query=Alberti%2C+A">Andrea Alberti</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="2408.04622v1-abstract-short" style="display: inline;"> We propose a scheme to perform optical pulses that suppress the effect of photon recoil by three orders of magnitude compared to ordinary pulses in the Lamb-Dicke regime. We derive analytical insight about the fundamental limits to the fidelity of optical qubits for trapped atoms and ions. This paves the way towards applications in quantum computing for realizing $>1000$ of gates with an overall f… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04622v1-abstract-full').style.display = 'inline'; document.getElementById('2408.04622v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.04622v1-abstract-full" style="display: none;"> We propose a scheme to perform optical pulses that suppress the effect of photon recoil by three orders of magnitude compared to ordinary pulses in the Lamb-Dicke regime. We derive analytical insight about the fundamental limits to the fidelity of optical qubits for trapped atoms and ions. This paves the way towards applications in quantum computing for realizing $>1000$ of gates with an overall fidelity above 99\%. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04622v1-abstract-full').style.display = 'none'; document.getElementById('2408.04622v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <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 plus appendices and bibliography, 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/2408.03109">arXiv:2408.03109</a> <span> [<a href="https://arxiv.org/pdf/2408.03109">pdf</a>, <a href="https://arxiv.org/format/2408.03109">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Exceptional point and hysteresis trajectories in cold Rydberg atomic gases </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+E">En-Ze Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Ya-Jun Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Li-Hua Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zheng-Yuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Shao%2C+S">Shi-Yao Shao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qing Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Han-Chao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yu Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+T">Tian-Yu Han</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qi-Feng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Nan%2C+J">Jia-Dou Nan</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+Y">Yi-Ming Ying</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+D">Dong-Yang Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+B">Bao-Sen Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+D">Dong-Sheng Ding</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="2408.03109v1-abstract-short" style="display: inline;"> The interplay between strong long-range interactions and the coherent driving contribute to the formation of complex patterns, symmetry, and novel phases of matter in many-body systems. However, long-range interactions may induce an additional dissipation channel, resulting in non-Hermitian many-body dynamics and the emergence of exceptional points in spectrum. Here, we report experimental observa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.03109v1-abstract-full').style.display = 'inline'; document.getElementById('2408.03109v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.03109v1-abstract-full" style="display: none;"> The interplay between strong long-range interactions and the coherent driving contribute to the formation of complex patterns, symmetry, and novel phases of matter in many-body systems. However, long-range interactions may induce an additional dissipation channel, resulting in non-Hermitian many-body dynamics and the emergence of exceptional points in spectrum. Here, we report experimental observation of interaction-induced exceptional points in cold Rydberg atomic gases, revealing the breaking of charge-conjugation parity symmetry. By measuring the transmission spectrum under increasing and decreasing probe intensity, the interaction-induced hysteresis trajectories are observed, which give rise to non-Hermitian dynamics. We record the area enclosed by hysteresis loops and investigate the dynamics of hysteresis loops. The reported exceptional points and hysteresis trajectories in cold Rydberg atomic gases provide valuable insights into the underlying non-Hermitian physics in many-body systems, allowing us to study the interplay between long-range interactions and non-Hermiticity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.03109v1-abstract-full').style.display = 'none'; document.getElementById('2408.03109v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.00464">arXiv:2408.00464</a> <span> [<a href="https://arxiv.org/pdf/2408.00464">pdf</a>, <a href="https://arxiv.org/format/2408.00464">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"> Optimally robust shortcuts to population inversion in cat-state qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+S">Shao-Wei Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhong-Zheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yue-Ying Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Ye-Hong Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Xia%2C+Y">Yan Xia</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="2408.00464v1-abstract-short" style="display: inline;"> Cat-state qubits formed by photonic coherent states are a promising candidate for realizing fault-tolerant quantum computing. Such logic qubits have a biased noise channel that the bit-flip error dominates over all the other errors. In this manuscript, we propose an optimally robust protocol using the control method of shortcuts to adiabaticity to realize a nearly perfect population inversion in a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.00464v1-abstract-full').style.display = 'inline'; document.getElementById('2408.00464v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.00464v1-abstract-full" style="display: none;"> Cat-state qubits formed by photonic coherent states are a promising candidate for realizing fault-tolerant quantum computing. Such logic qubits have a biased noise channel that the bit-flip error dominates over all the other errors. In this manuscript, we propose an optimally robust protocol using the control method of shortcuts to adiabaticity to realize a nearly perfect population inversion in a cat-state qubit. We construct a shortcut based on the Lewis-Riesenfeld invariant and examine the stability versus different types of perturbations for the fast and robust population inversion. Numerical simulations demonstrate that the population inversion can be mostly insensitive to systematic errors in our protocol. Even when the parameter imperfection rate for bit-flip control is $20\%$, the final population of the target state can still reach $\geq 99\%$. The optimally robust control provides a feasible method for fault-tolerant and scalable quantum computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.00464v1-abstract-full').style.display = 'none'; document.getElementById('2408.00464v1-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 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">9 pages, 8 figures, comments are welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.20298">arXiv:2407.20298</a> <span> [<a href="https://arxiv.org/pdf/2407.20298">pdf</a>, <a href="https://arxiv.org/format/2407.20298">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"> Efficient Circuit-Based Quantum State Tomography via Sparse Entry Optimization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chi-Kwong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+K+Y">Kevin Yipu Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zherui 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="2407.20298v1-abstract-short" style="display: inline;"> We propose an efficient circuit-based quantum state tomography (QST) scheme to reconstruct $n$-qubit states with $k$ nonzero entries using measurements of $|蠄\rangle$ and $U_1|蠄\rangle, \dots, U_{2m}|蠄\rangle$, where $m \le k$. Each $U_j$ involves CNOT gates followed by a single-qubit gate, either Hadamard $H$ or $HD$, where $D = {\rm diag}(1,i)$, targeting a specific qubit. We provide an upper li… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.20298v1-abstract-full').style.display = 'inline'; document.getElementById('2407.20298v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.20298v1-abstract-full" style="display: none;"> We propose an efficient circuit-based quantum state tomography (QST) scheme to reconstruct $n$-qubit states with $k$ nonzero entries using measurements of $|蠄\rangle$ and $U_1|蠄\rangle, \dots, U_{2m}|蠄\rangle$, where $m \le k$. Each $U_j$ involves CNOT gates followed by a single-qubit gate, either Hadamard $H$ or $HD$, where $D = {\rm diag}(1,i)$, targeting a specific qubit. We provide an upper limit on the number of CNOT gates based on the nonzero entries' positions in $|蠄\rangle$. This approach, applied to both state and process tomography, was tested using the Qiskit simulator. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.20298v1-abstract-full').style.display = 'none'; document.getElementById('2407.20298v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 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">23 page, 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/2407.15438">arXiv:2407.15438</a> <span> [<a href="https://arxiv.org/pdf/2407.15438">pdf</a>, <a href="https://arxiv.org/format/2407.15438">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Integrated Mode-Hop-Free Tunable Lasers at 780 nm for Chip-Scale Classical and Quantum Photonic Applications </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Castro%2C+J+E">Joshua E. Castro</a>, <a href="/search/quant-ph?searchtype=author&query=Nolasco-Martinez%2C+E">Eber Nolasco-Martinez</a>, <a href="/search/quant-ph?searchtype=author&query=Pintus%2C+P">Paolo Pintus</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zeyu Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+B">Boqiang Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Morin%2C+T">Theodore Morin</a>, <a href="/search/quant-ph?searchtype=author&query=Thiel%2C+L">Lillian Thiel</a>, <a href="/search/quant-ph?searchtype=author&query=Steiner%2C+T+J">Trevor J. Steiner</a>, <a href="/search/quant-ph?searchtype=author&query=Lewis%2C+N">Nicholas Lewis</a>, <a href="/search/quant-ph?searchtype=author&query=Patel%2C+S+D">Sahil D. Patel</a>, <a href="/search/quant-ph?searchtype=author&query=Bowers%2C+J+E">John E. Bowers</a>, <a href="/search/quant-ph?searchtype=author&query=Weld%2C+D+M">David M. Weld</a>, <a href="/search/quant-ph?searchtype=author&query=Moody%2C+G">Galan Moody</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="2407.15438v1-abstract-short" style="display: inline;"> In the last decade, remarkable advances in integrated photonic technologies have enabled table-top experiments and instrumentation to be scaled down to compact chips with significant reduction in size, weight, power consumption, and cost. Here, we demonstrate an integrated continuously tunable laser in a heterogeneous gallium arsenide-on-silicon nitride (GaAs-on-SiN) platform that emits in the far… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15438v1-abstract-full').style.display = 'inline'; document.getElementById('2407.15438v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.15438v1-abstract-full" style="display: none;"> In the last decade, remarkable advances in integrated photonic technologies have enabled table-top experiments and instrumentation to be scaled down to compact chips with significant reduction in size, weight, power consumption, and cost. Here, we demonstrate an integrated continuously tunable laser in a heterogeneous gallium arsenide-on-silicon nitride (GaAs-on-SiN) platform that emits in the far-red radiation spectrum near 780 nm, with 20 nm tuning range, <6 kHz intrinsic linewidth, and a >40 dB side-mode suppression ratio. The GaAs optical gain regions are heterogeneously integrated with low-loss SiN waveguides. The narrow linewidth lasing is achieved with an extended cavity consisting of a resonator-based Vernier mirror and a phase shifter. Utilizing synchronous tuning of the integrated heaters, we show mode-hop-free wavelength tuning over a range larger than 100 GHz (200 pm). To demonstrate the potential of the device, we investigate two illustrative applications: (i) the linear characterization of a silicon nitride microresonator designed for entangled-photon pair generation, and (ii) the absorption spectroscopy and locking to the D1 and D2 transition lines of 87-Rb. The performance of the proposed integrated laser holds promise for a broader spectrum of both classical and quantum applications in the visible range, encompassing communication, control, sensing, and computing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15438v1-abstract-full').style.display = 'none'; document.getElementById('2407.15438v1-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, 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/2407.15387">arXiv:2407.15387</a> <span> [<a href="https://arxiv.org/pdf/2407.15387">pdf</a>, <a href="https://arxiv.org/format/2407.15387">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> A Nanomechanical Atomic Force Qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Jahanbani%2C+S">Shahin Jahanbani</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zi-Huai Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+B">Binhan Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Godeneli%2C+K">Kadircan Godeneli</a>, <a href="/search/quant-ph?searchtype=author&query=M%C3%BCllendorff%2C+B">Boris M眉llendorff</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xueyue Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+H">Haoxin Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Sipahigil%2C+A">Alp Sipahigil</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="2407.15387v1-abstract-short" style="display: inline;"> Silicon nanomechanical resonators display ultra-long lifetimes at cryogenic temperatures and microwave frequencies. Achieving quantum control of single-phonons in these devices has so far relied on nonlinearities enabled by coupling to ancillary qubits. In this work, we propose using atomic forces to realize a silicon nanomechanical qubit without coupling to an ancillary qubit. The proposed qubit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15387v1-abstract-full').style.display = 'inline'; document.getElementById('2407.15387v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.15387v1-abstract-full" style="display: none;"> Silicon nanomechanical resonators display ultra-long lifetimes at cryogenic temperatures and microwave frequencies. Achieving quantum control of single-phonons in these devices has so far relied on nonlinearities enabled by coupling to ancillary qubits. In this work, we propose using atomic forces to realize a silicon nanomechanical qubit without coupling to an ancillary qubit. The proposed qubit operates at 60 MHz with a single-phonon level anharmonicity of 5 MHz. We present a circuit quantum acoustodynamics architecture where electromechanical resonators enable dispersive state readout and multi-qubit operations. The combination of strong anharmonicity, ultrahigh mechanical quality factors, and small footprints achievable in this platform could enable quantum-nonlinear phononics for quantum information processing and transduction. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15387v1-abstract-full').style.display = 'none'; document.getElementById('2407.15387v1-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, 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/2407.09932">arXiv:2407.09932</a> <span> [<a href="https://arxiv.org/pdf/2407.09932">pdf</a>, <a href="https://arxiv.org/format/2407.09932">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum Clock Synchronization Network with Silicon-chip Dual-Pumped Entangled Photon Source </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+J+A">J. A. Li</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+H">H. Han</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+X+P">X. P. Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+B+Y">B. Y. Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+K">K. Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+J+Q">J. Q. Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Xiong%2C+S+Y">S. Y. Xiong</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+W+R">W. R. Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z+J">Z. J. Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+J+B">J. B. Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">B. Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">H. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Z+K">Z. K. Lu</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="2407.09932v1-abstract-short" style="display: inline;"> In this paper, we propose a quantum clock synchronization (QCS) network scheme with silicon-chip dual-pumped entangled photon source. This scheme couples two pump beams into the silicon-based waveguide, where degenerate and non-degenerate spontaneous four-wave mixing (SFWM) occurs, generating entanglement between one signal channel and three idler channels. The entangled photons are distributed to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.09932v1-abstract-full').style.display = 'inline'; document.getElementById('2407.09932v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.09932v1-abstract-full" style="display: none;"> In this paper, we propose a quantum clock synchronization (QCS) network scheme with silicon-chip dual-pumped entangled photon source. This scheme couples two pump beams into the silicon-based waveguide, where degenerate and non-degenerate spontaneous four-wave mixing (SFWM) occurs, generating entanglement between one signal channel and three idler channels. The entangled photons are distributed to remote users through the wavelength division multiplexing strategy to construct an entanglement distribution network, and the round-trip QCS is adopted to realize a QCS network that can serve multiple users. A proof-of-principle QCS network experiment is implemented among the server and multiple users (Alice, Bob, and Charlie) for 11.1 hours, where Alice and Charlie are 10 km away from the server and Bob is 25 km away from the server. The lowest time deviations (TDEV) between the server and each user (Alice, Bob, and Charlie) are 1.57 ps, 0.82 ps and 2.57 ps at the average time of 8000 s, 8000 s and 800 s respectively. The results show that the QCS network scheme with dual-pumped SFWM photon source proposed by us achieves high accuracy, and the channel resources used by n users are reduced by about 30% compared with other round-trip QCS schemes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.09932v1-abstract-full').style.display = 'none'; document.getElementById('2407.09932v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 July, 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/2407.07513">arXiv:2407.07513</a> <span> [<a href="https://arxiv.org/pdf/2407.07513">pdf</a>, <a href="https://arxiv.org/format/2407.07513">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-rate quantum digital signatures network with integrated silicon photonics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Du%2C+Y">Yongqiang Du</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bing-Hong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+X">Xin Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+X">Xiao-Yu Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Z">Zhengeng Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+F">Feng Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+X">Xi Xiao</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin 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="2407.07513v1-abstract-short" style="display: inline;"> The development of quantum networks is paramount towards practical and secure communications. Quantum digital signatures (QDS) offer an information-theoretically secure solution for ensuring data integrity, authenticity, and non-repudiation, rapidly growing from proof-of-concept to robust demonstrations. However, previous QDS systems relied on expensive and bulky optical equipment, limiting large-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.07513v1-abstract-full').style.display = 'inline'; document.getElementById('2407.07513v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.07513v1-abstract-full" style="display: none;"> The development of quantum networks is paramount towards practical and secure communications. Quantum digital signatures (QDS) offer an information-theoretically secure solution for ensuring data integrity, authenticity, and non-repudiation, rapidly growing from proof-of-concept to robust demonstrations. However, previous QDS systems relied on expensive and bulky optical equipment, limiting large-scale deployment and reconfigurable networking construction. Here, we introduce and verify a chip-based QDS network, placing the complicated and expensive measurement devices in the central relay while each user needs only a low-cost transmitter. We demonstrate the network with a three-node setup using an integrated encoder chip and decoder chip. By developing a 1-decoy-state one-time universal hash-QDS protocol, we achieve a maximum signature rate of 0.0414 times per second for a 1 Mbit file over fiber distances up to 200 km, surpassing all current state-of-the-art QDS experiments. This study validates the feasibility of chip-based QDS, paving the way for large-scale deployment and integration with existing fiber infrastructure. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.07513v1-abstract-full').style.display = 'none'; document.getElementById('2407.07513v1-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.06534">arXiv:2407.06534</a> <span> [<a href="https://arxiv.org/pdf/2407.06534">pdf</a>, <a href="https://arxiv.org/format/2407.06534">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"> Lamb Shift Breaks the Heat Current Limit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zi-chen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+C">Chang-shui Yu</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="2407.06534v1-abstract-short" style="display: inline;"> We study the Lamb shift by considering the steady-state heat current through two coupled two-level atoms, which, respectively, interact with a heat reservoir at a certain temperature. It is found that the Lamb shift significantly alters the energy levels. In particular, it is shown that the heat current will approach an upper bound if the Lamb shift isn't considered, while the heat current will br… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06534v1-abstract-full').style.display = 'inline'; document.getElementById('2407.06534v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.06534v1-abstract-full" style="display: none;"> We study the Lamb shift by considering the steady-state heat current through two coupled two-level atoms, which, respectively, interact with a heat reservoir at a certain temperature. It is found that the Lamb shift significantly alters the energy levels. In particular, it is shown that the heat current will approach an upper bound if the Lamb shift isn't considered, while the heat current will break the upper bound if the Lamb shift is considered. This finding can deepen our understanding of Lamb shift in the quantum thermodynamic field. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06534v1-abstract-full').style.display = 'none'; document.getElementById('2407.06534v1-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 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/2407.06012">arXiv:2407.06012</a> <span> [<a href="https://arxiv.org/pdf/2407.06012">pdf</a>, <a href="https://arxiv.org/ps/2407.06012">ps</a>, <a href="https://arxiv.org/format/2407.06012">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="Computational Complexity">cs.CC</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.110.012422">10.1103/PhysRevA.110.012422 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tight Quantum Depth Lower Bound for Solving Systems of Linear Equations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qisheng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhicheng 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="2407.06012v2-abstract-short" style="display: inline;"> Since Harrow, Hassidim, and Lloyd (2009) showed that a system of linear equations with $N$ variables and condition number $魏$ can be solved on a quantum computer in $\operatorname{poly}(\log(N), 魏)$ time, exponentially faster than any classical algorithms, its improvements and applications have been extensively investigated. The state-of-the-art quantum algorithm for this problem is due to Costa,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06012v2-abstract-full').style.display = 'inline'; document.getElementById('2407.06012v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.06012v2-abstract-full" style="display: none;"> Since Harrow, Hassidim, and Lloyd (2009) showed that a system of linear equations with $N$ variables and condition number $魏$ can be solved on a quantum computer in $\operatorname{poly}(\log(N), 魏)$ time, exponentially faster than any classical algorithms, its improvements and applications have been extensively investigated. The state-of-the-art quantum algorithm for this problem is due to Costa, An, Sanders, Su, Babbush, and Berry (2022), with optimal query complexity $螛(魏)$. An important question left is whether parallelism can bring further optimization. In this paper, we study the limitation of parallel quantum computing on this problem. We show that any quantum algorithm for solving systems of linear equations with time complexity $\operatorname{poly}(\log(N), 魏)$ has a lower bound of $惟(魏)$ on the depth of queries, which is tight up to a constant factor. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06012v2-abstract-full').style.display = 'none'; document.getElementById('2407.06012v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 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">Minor corrections to references in [v1]. 22 pages, 1 table. Close to the official version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review A, 110(1): 012422, 2024 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.03980">arXiv:2407.03980</a> <span> [<a href="https://arxiv.org/pdf/2407.03980">pdf</a>, <a href="https://arxiv.org/format/2407.03980">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"> Practical asynchronous measurement-device-independent quantum key distribution with advantage distillation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Luo%2C+D">Di Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+K">Kaibiao Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin 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="2407.03980v1-abstract-short" style="display: inline;"> The advantage distillation (AD) method has proven effective in improving the performance of quantum key distribution (QKD). In this paper, we introduce the AD method into a recently proposed asynchronous measurement-device-independent (AMDI) QKD protocol, taking finite-key effects into account. Simulation results show that the AD method significantly enhances AMDIQKD, e.g., extending the transmiss… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.03980v1-abstract-full').style.display = 'inline'; document.getElementById('2407.03980v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.03980v1-abstract-full" style="display: none;"> The advantage distillation (AD) method has proven effective in improving the performance of quantum key distribution (QKD). In this paper, we introduce the AD method into a recently proposed asynchronous measurement-device-independent (AMDI) QKD protocol, taking finite-key effects into account. Simulation results show that the AD method significantly enhances AMDIQKD, e.g., extending the transmission distance by 16 km with a total pulse count of N = 7.24*10^13, and enables AMDI-QKD, previously unable to generate keys, to generate keys with a misalignment error rate of 10%. As the AD method can be directly integrated into the current system through refined post-processing, our results facilitate the practical implementation of AMDI-QKD in various applications, particularly in scenarios with high channel losses and misalignment errors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.03980v1-abstract-full').style.display = 'none'; document.getElementById('2407.03980v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 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">13 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.00363">arXiv:2407.00363</a> <span> [<a href="https://arxiv.org/pdf/2407.00363">pdf</a>, <a href="https://arxiv.org/format/2407.00363">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"> Goos-H{盲}nchen Shift for Relativistic Particles Based on Dirac's Equation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+J">Jiang-Lin Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhen-Xiao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+X">Xing-Yan Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jing-Ling 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="2407.00363v1-abstract-short" style="display: inline;"> The Goos-H{盲}nchen (GH) shift is a specifical optical phenomenon that describes a shift parallel to the reflected light inside the plane of incidence, when a finite-width light undergoes total internal reflection at the interface of medium. Although the GH shift in optics has been widely observed experimentally, its generalization remains uncovered completely in relativistic quantum mechanics for… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.00363v1-abstract-full').style.display = 'inline'; document.getElementById('2407.00363v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.00363v1-abstract-full" style="display: none;"> The Goos-H{盲}nchen (GH) shift is a specifical optical phenomenon that describes a shift parallel to the reflected light inside the plane of incidence, when a finite-width light undergoes total internal reflection at the interface of medium. Although the GH shift in optics has been widely observed experimentally, its generalization remains uncovered completely in relativistic quantum mechanics for the existence of Klein's paradox. Recently, Wang has solved Klein's paradox based on the different solutions adpoted for Dirac's equation with step potential in corresponding energy regions \href{https://dx.doi.org/10.1088/2399-6528/abd340}{[J. Phys. Commun. {\bf 4}, 125010 (2020)]}. In the light of Wang's method, we calculate the GH shift for Dirac fermions under relativistic conditions when they are incident obliquely on a three-dimensional infinite potential barrier. Furthermore, we find that the relativistic quantum GH shift can be negative, which is different from the non-relativistic case. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.00363v1-abstract-full').style.display = 'none'; document.getElementById('2407.00363v1-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 June, 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">9 pages, 2 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.17178">arXiv:2406.17178</a> <span> [<a href="https://arxiv.org/pdf/2406.17178">pdf</a>, <a href="https://arxiv.org/format/2406.17178">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum illumination networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+X">Xiaobin Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zheshen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhuang%2C+Q">Quntao Zhuang</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="2406.17178v1-abstract-short" style="display: inline;"> Quantum illumination is an entanglement-based target detection protocol that provides quantum advantages despite the presence of entanglement-breaking noise. However, the advantage of traditional quantum illumination protocols is limited to impractical scenarios with low transmitted power and simple target configurations. In this work, we propose a quantum illumination network to overcome the limi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.17178v1-abstract-full').style.display = 'inline'; document.getElementById('2406.17178v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.17178v1-abstract-full" style="display: none;"> Quantum illumination is an entanglement-based target detection protocol that provides quantum advantages despite the presence of entanglement-breaking noise. However, the advantage of traditional quantum illumination protocols is limited to impractical scenarios with low transmitted power and simple target configurations. In this work, we propose a quantum illumination network to overcome the limitations, via designing a transmitter array and a single receiver antenna. Thanks to multiple transmitters, quantum advantage is achieved even with a high total transmitted power. Moreover, for single-parameter estimation, the advantage of network over a single transmitter case increases with the number of transmitters before saturation. At the same time, complex target configurations with multiple unknown transmissivity or phase parameters can be resolved. Despite the interference of different returning signals at the single antenna and photon-loss due to multiple-access channel, we provide two types of measurement design, one based on parametric-amplification and one based on the correlation-to-displacement conversion (CtoD) to achieve a quantum advantage in estimating all unknown parameters. We also generalize the parameter estimation scenario to a general hypothesis testing scenario, where the six-decibel quantum illumination advantage is achieved at a much greater total probing power. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.17178v1-abstract-full').style.display = 'none'; document.getElementById('2406.17178v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.11953">arXiv:2406.11953</a> <span> [<a href="https://arxiv.org/pdf/2406.11953">pdf</a>, <a href="https://arxiv.org/format/2406.11953">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> </div> <p class="title is-5 mathjax"> Intrinsic high-fidelity spin polarization of charged vacancies in hexagonal boron nitride </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lee%2C+W">Wonjae Lee</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+V+S">Vincent S. Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhelun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+S">Sangha Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+R">Ruotian Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+X">Xinyi Du</a>, <a href="/search/quant-ph?searchtype=author&query=Pham%2C+K">Khanh Pham</a>, <a href="/search/quant-ph?searchtype=author&query=Poirier%2C+T">Thomas Poirier</a>, <a href="/search/quant-ph?searchtype=author&query=Hao%2C+Z">Zeyu Hao</a>, <a href="/search/quant-ph?searchtype=author&query=Edgar%2C+J+H">James H. Edgar</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+P">Philip Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Zu%2C+C">Chong Zu</a>, <a href="/search/quant-ph?searchtype=author&query=Davis%2C+E+J">Emily J. Davis</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+N+Y">Norman Y. Yao</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.11953v1-abstract-short" style="display: inline;"> The negatively charged boron vacancy ($\mathrm{V}_{\mathrm{B}}^-$) in hexagonal boron nitride (hBN) has garnered significant attention among defects in two-dimensional materials. This owes, in part, to its deterministic generation, well-characterized atomic structure, and optical polarizability at room temperature. We investigate the latter through extensive measurements probing both the ground an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.11953v1-abstract-full').style.display = 'inline'; document.getElementById('2406.11953v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.11953v1-abstract-full" style="display: none;"> The negatively charged boron vacancy ($\mathrm{V}_{\mathrm{B}}^-$) in hexagonal boron nitride (hBN) has garnered significant attention among defects in two-dimensional materials. This owes, in part, to its deterministic generation, well-characterized atomic structure, and optical polarizability at room temperature. We investigate the latter through extensive measurements probing both the ground and excited state polarization dynamics. We develop a semiclassical model based on these measurements that predicts a near-unity degree of spin polarization, surpassing other solid-state spin defects under ambient conditions. Building upon our model, we include the presence of nuclear spin degrees of freedom adjacent to the $\mathrm{V}_{\mathrm{B}}^-$ and perform a comprehensive set of Lindbladian numerics to investigate the hyperfine-induced polarization of the nuclear spins. Our simulations predict a number of important features that emerge as a function of magnetic field which are borne out by experiment. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.11953v1-abstract-full').style.display = 'none'; document.getElementById('2406.11953v1-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> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.02669">arXiv:2406.02669</a> <span> [<a href="https://arxiv.org/pdf/2406.02669">pdf</a>, <a href="https://arxiv.org/format/2406.02669">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"> A generalized cycle benchmarking algorithm for characterizing mid-circuit measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhihan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Senrui Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yunchao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.02669v2-abstract-short" style="display: inline;"> Mid-circuit measurements (MCMs) are crucial ingredients in the development of fault-tolerant quantum computation. While there have been rapid experimental progresses in realizing MCMs, a systematic method for characterizing noisy MCMs is still under exploration. In this work we develop a cycle benchmarking (CB)-type algorithm to characterize noisy MCMs. The key idea is to use a joint Fourier trans… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.02669v2-abstract-full').style.display = 'inline'; document.getElementById('2406.02669v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.02669v2-abstract-full" style="display: none;"> Mid-circuit measurements (MCMs) are crucial ingredients in the development of fault-tolerant quantum computation. While there have been rapid experimental progresses in realizing MCMs, a systematic method for characterizing noisy MCMs is still under exploration. In this work we develop a cycle benchmarking (CB)-type algorithm to characterize noisy MCMs. The key idea is to use a joint Fourier transform on the classical and quantum registers and then estimate parameters in the Fourier space, analogous to Pauli fidelities used in CB-type algorithms for characterizing the Pauli noise channel of Clifford gates. Furthermore, we develop a theory of the noise learnability of MCMs, which determines what information can be learned about the noise model (in the presence of state preparation and terminating measurement (SPAM) noise) and what cannot, which shows that all learnable information can be learned using our algorithm. As an application, we show how to use the learned information to test the independence between measurement noise and state preparation noise in an MCM. Finally, we conduct numerical simulations to illustrate the practical applicability of the algorithm. Similar to other CB-type algorithms, we expect the algorithm to provide a useful toolkit that is of experimental interest. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.02669v2-abstract-full').style.display = 'none'; document.getElementById('2406.02669v2-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 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">30 pages, 9 figures, 1 table</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.00268">arXiv:2406.00268</a> <span> [<a href="https://arxiv.org/pdf/2406.00268">pdf</a>, <a href="https://arxiv.org/format/2406.00268">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.109.184314">10.1103/PhysRevB.109.184314 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Magnetization in a non-equilibrium quantum spin system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X+Z">X. Z. 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="2406.00268v1-abstract-short" style="display: inline;"> The dynamics described by the non-Hermitian Hamiltonian typically capture the short-term behavior of open quantum systems before quantum jumps occur. In contrast, the long-term dynamics, characterized by the Lindblad master equation (LME), drive the system towards a non-equilibrium steady state (NESS), which is an eigenstate with zero energy of the Liouvillian superoperator, denoted as… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.00268v1-abstract-full').style.display = 'inline'; document.getElementById('2406.00268v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.00268v1-abstract-full" style="display: none;"> The dynamics described by the non-Hermitian Hamiltonian typically capture the short-term behavior of open quantum systems before quantum jumps occur. In contrast, the long-term dynamics, characterized by the Lindblad master equation (LME), drive the system towards a non-equilibrium steady state (NESS), which is an eigenstate with zero energy of the Liouvillian superoperator, denoted as $\mathcal{L}$. Conventionally, these two types of evolutions exhibit distinct dynamical behaviors. However, in this study, we challenge this common belief and demonstrate that the effective non-Hermitian Hamiltonian can accurately represent the long-term dynamics of a critical two-level open quantum system. The criticality of the system arises from the exceptional point (EP) of the effective non-Hermitian Hamiltonian. Additionally, the NESS is identical to the coalescent state of the effective non-Hermitian Hamiltonian. We apply this finding to a series of critical open quantum systems and show that a local dissipation channel can induce collective alignment of all spins in the same direction. This direction can be well controlled by modulating the quantum jump operator. The corresponding NESS is a product state and maintains long-time coherence, facilitating quantum control in open many-body systems. This discovery paves the way for a better understanding of the long-term dynamics of critical open quantum systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.00268v1-abstract-full').style.display = 'none'; document.getElementById('2406.00268v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 May, 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">13 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 109, 184314 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.16558">arXiv:2405.16558</a> <span> [<a href="https://arxiv.org/pdf/2405.16558">pdf</a>, <a href="https://arxiv.org/format/2405.16558">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Experimental Refrence-Frame-Independent Quantum Key Distribution over 250 km of Optical Fiber </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+D">Di Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+Z">Zhicheng Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shizhuo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin 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="2405.16558v1-abstract-short" style="display: inline;"> The reference-frame-independent quantum key distribution (RFI-QKD) protocol enables QKD systems to function effectively despite slowly varying reference frames, offering a distinct advantage in practical scenarios, particularly in mobile platforms. In this study, we successfully distribute secure key bits over a 250 km optical fiber distance by developing an RFI-QKD system with a repetition rate o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.16558v1-abstract-full').style.display = 'inline'; document.getElementById('2405.16558v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.16558v1-abstract-full" style="display: none;"> The reference-frame-independent quantum key distribution (RFI-QKD) protocol enables QKD systems to function effectively despite slowly varying reference frames, offering a distinct advantage in practical scenarios, particularly in mobile platforms. In this study, we successfully distribute secure key bits over a 250 km optical fiber distance by developing an RFI-QKD system with a repetition rate of 150 MHz. Benefiting from high repetition rate, we achieve a finite-key secret key rate of 49.65 bit/s at a distance of 200 km, which is more than three times higher than state-of-the-art systems. Our work dramatically extends the transmission distance and enhances the secret key rate of RFI-QKD, significantly promoting its practical application. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.16558v1-abstract-full').style.display = 'none'; document.getElementById('2405.16558v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 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">9 pages,4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.12102">arXiv:2405.12102</a> <span> [<a href="https://arxiv.org/pdf/2405.12102">pdf</a>, <a href="https://arxiv.org/format/2405.12102">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="Chemical Physics">physics.chem-ph</span> </div> </div> <p class="title is-5 mathjax"> Collective Quantum Entanglement in Molecular Cavity Optomechanics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+J">Jian Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Lei%2C+D">Dangyuan Lei</a>, <a href="/search/quant-ph?searchtype=author&query=Agarwal%2C+G+S">Girish S. Agarwal</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhedong 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="2405.12102v3-abstract-short" style="display: inline;"> We propose an optomechanical scheme for reaching quantum entanglement in vibration polaritons. The system involves $N$ molecules, whose vibrations can be fairly entangled with plasmonic cavities. We find that the vibration-photon entanglement can exist at room temperature and is robust against thermal noise. We further demonstrate the quantum entanglement between the vibrational modes through the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.12102v3-abstract-full').style.display = 'inline'; document.getElementById('2405.12102v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.12102v3-abstract-full" style="display: none;"> We propose an optomechanical scheme for reaching quantum entanglement in vibration polaritons. The system involves $N$ molecules, whose vibrations can be fairly entangled with plasmonic cavities. We find that the vibration-photon entanglement can exist at room temperature and is robust against thermal noise. We further demonstrate the quantum entanglement between the vibrational modes through the plasmonic cavities, which shows a delocalized nature and an incredible enhancement with the number of molecules. The underlying mechanism for the entanglement is attributed to the strong vibration-cavity coupling which possesses collectivity. Our results provide a molecular optomechanical scheme which offers a promising platform for the study of noise-free quantum resources and macroscopic quantum phenomena. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.12102v3-abstract-full').style.display = 'none'; document.getElementById('2405.12102v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 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">10 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.10151">arXiv:2405.10151</a> <span> [<a href="https://arxiv.org/pdf/2405.10151">pdf</a>, <a href="https://arxiv.org/format/2405.10151">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-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"> Relativistic EELS scattering cross-sections for microanalysis based on Dirac solutions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zezhong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Lobato%2C+I">Ivan Lobato</a>, <a href="/search/quant-ph?searchtype=author&query=Brown%2C+H">Hamish Brown</a>, <a href="/search/quant-ph?searchtype=author&query=Lamoen%2C+D">Dirk Lamoen</a>, <a href="/search/quant-ph?searchtype=author&query=Jannis%2C+D">Daen Jannis</a>, <a href="/search/quant-ph?searchtype=author&query=Verbeeck%2C+J">Johan Verbeeck</a>, <a href="/search/quant-ph?searchtype=author&query=Van+Aert%2C+S">Sandra Van Aert</a>, <a href="/search/quant-ph?searchtype=author&query=Nellist%2C+P+D">Peter D. Nellist</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="2405.10151v1-abstract-short" style="display: inline;"> The rich information of electron energy-loss spectroscopy (EELS) comes from the complex inelastic scattering process whereby fast electrons transfer energy and momentum to atoms, exciting bound electrons from their ground states to higher unoccupied states. To quantify EELS, the common practice is to compare the cross-sections integrated within an energy window or fit the observed spectrum with th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.10151v1-abstract-full').style.display = 'inline'; document.getElementById('2405.10151v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.10151v1-abstract-full" style="display: none;"> The rich information of electron energy-loss spectroscopy (EELS) comes from the complex inelastic scattering process whereby fast electrons transfer energy and momentum to atoms, exciting bound electrons from their ground states to higher unoccupied states. To quantify EELS, the common practice is to compare the cross-sections integrated within an energy window or fit the observed spectrum with theoretical differential cross-sections calculated from a generalized oscillator strength (GOS) database with experimental parameters. The previous Hartree-Fock-based and DFT-based GOS are calculated from Schr枚dinger's solution of atomic orbitals, which does not include the full relativistic effects. Here, we attempt to go beyond the limitations of the Schr枚dinger solution in the GOS tabulation by including the full relativistic effects using the Dirac equation within the local density approximation, which is particularly important for core-shell electrons of heavy elements with strong spin-orbit coupling. This has been done for all elements in the periodic table (up to Z = 118) for all possible excitation edges using modern computing capabilities and parallelization algorithms. The relativistic effects of fast incoming electrons were included to calculate cross-sections that are specific to the acceleration voltage. We make these tabulated GOS available under an open-source license to the benefit of both academic users as well as allowing integration into commercial solutions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.10151v1-abstract-full').style.display = 'none'; document.getElementById('2405.10151v1-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 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">52 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/2405.09116">arXiv:2405.09116</a> <span> [<a href="https://arxiv.org/pdf/2405.09116">pdf</a>, <a href="https://arxiv.org/format/2405.09116">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"> Atomic transport dynamics in crossed optical dipole trap </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Peng%2C+P">Peng Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhengxi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+Y">Yaoyuan Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+G">Guoling Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Mao%2C+D">Dekai Mao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+X">Xuzong Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Xiong%2C+W">Wei Xiong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+X">Xiaoji Zhou</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.09116v1-abstract-short" style="display: inline;"> We study the dynamical evolution of cold atoms in crossed optical dipole trap theoretically and experimentally. The atomic transport process is accompanied by two competitive kinds of physical mechanics, atomic loading and atomic loss. The loading process normally is negligible in the evaporative cooling experiment on the ground, while it is significant in the preparation of ultra-cold atoms in th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.09116v1-abstract-full').style.display = 'inline'; document.getElementById('2405.09116v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.09116v1-abstract-full" style="display: none;"> We study the dynamical evolution of cold atoms in crossed optical dipole trap theoretically and experimentally. The atomic transport process is accompanied by two competitive kinds of physical mechanics, atomic loading and atomic loss. The loading process normally is negligible in the evaporative cooling experiment on the ground, while it is significant in the preparation of ultra-cold atoms in the space station. Normally, the atomic loading process is much weaker than the atomic loss process, and the atomic number in the center region of the trap decreases monotonically, as reported in previous research. However, when the atomic loading process is comparable to the atomic loss process, the atomic number in the center region of the trap will initially increase to a maximum value and then slowly decrease, and we have observed the phenomenon first. The increase of atomic number in the center region of the trap shows the presence of the loading process, and this will be significant especially under microgravity conditions. We build a theoretical model to analyze the competitive relationship, which coincides with the experimental results well. Furthermore, we have also given the predicted evolutionary behaviors under different conditions. This research provides a solid foundation for further understanding of the atomic transport process in traps. The analysis of loading process is of significant importance for the preparation of ultra-cold atoms in a crossed optical dipole trap under microgravity conditions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.09116v1-abstract-full').style.display = 'none'; document.getElementById('2405.09116v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 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/2405.07880">arXiv:2405.07880</a> <span> [<a href="https://arxiv.org/pdf/2405.07880">pdf</a>, <a href="https://arxiv.org/ps/2405.07880">ps</a>, <a href="https://arxiv.org/format/2405.07880">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mathematical Physics">math-ph</span> <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"> On Hagedorn wavepackets associated with different Gaussians </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Van%C3%AD%C4%8Dek%2C+J+J+L">Ji艡铆 J. L. Van铆膷ek</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z+T">Zhan Tong 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="2405.07880v4-abstract-short" style="display: inline;"> Hagedorn functions are carefully constructed generalizations of Hermite functions to the setting of many-dimensional squeezed and coupled harmonic systems. Wavepackets formed by superpositions of Hagedorn functions have been successfully used to solve the time-dependent Schr枚dinger equation exactly in harmonic systems and variationally in anharmonic systems. For evaluating typical observables, suc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07880v4-abstract-full').style.display = 'inline'; document.getElementById('2405.07880v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.07880v4-abstract-full" style="display: none;"> Hagedorn functions are carefully constructed generalizations of Hermite functions to the setting of many-dimensional squeezed and coupled harmonic systems. Wavepackets formed by superpositions of Hagedorn functions have been successfully used to solve the time-dependent Schr枚dinger equation exactly in harmonic systems and variationally in anharmonic systems. For evaluating typical observables, such as position or kinetic energy, it is sufficient to consider orthonormal Hagedorn functions with a single Gaussian center. Here, we instead derive various relations between Hagedorn bases associated with different Gaussians, including their overlaps, which are necessary for evaluating quantities nonlocal in time, such as time correlation functions needed for computing spectra. First, we use the Bogoliubov transformation to obtain commutation relations between the ladder operators associated with different Gaussians. Then, instead of using numerical quadrature, we employ these commutation relations to derive exact recurrence relations for the overlap integrals between Hagedorn functions with different Gaussian centers. Finally, we present numerical experiments that demonstrate the accuracy and efficiency of our algebraic method as well as its suitability to treat problems in spectroscopy and chemical dynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07880v4-abstract-full').style.display = 'none'; document.getElementById('2405.07880v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 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">26 pages, 2 figures; corrected the prefactor in eqs. 43, 65 and 66</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.07469">arXiv:2405.07469</a> <span> [<a href="https://arxiv.org/pdf/2405.07469">pdf</a>, <a href="https://arxiv.org/format/2405.07469">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="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Phase coding semi-quantum key distribution system based on the Single-state protocol </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hou%2C+Q">Qincheng Hou</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+S">Siying Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Mo%2C+N">Naida Mo</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Jindong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+Z">Zhengjun Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+Y">Yafei Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+T">Tianming Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhiming 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="2405.07469v1-abstract-short" style="display: inline;"> Semi-quantum key distribution (SQKD) allows sharing random keys between a quantum user and a classical user. However, implementing classical user operations is challenging, posing a hurdle to achieving the Single-state protocol. By using the "selective modulation" method, the feasibility of SQKD is verified in principle. The proposal of the selective modulation method enables the realization of ot… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07469v1-abstract-full').style.display = 'inline'; document.getElementById('2405.07469v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.07469v1-abstract-full" style="display: none;"> Semi-quantum key distribution (SQKD) allows sharing random keys between a quantum user and a classical user. However, implementing classical user operations is challenging, posing a hurdle to achieving the Single-state protocol. By using the "selective modulation" method, the feasibility of SQKD is verified in principle. The proposal of the selective modulation method enables the realization of other protocols for SQKD. To advance experimental progress in SQKD, we propose and implement a phase-encoded semi-quantum key distribution system based on the Single-state protocol and the "selective modulation" method. The system operates at a frequency of 100MHz and an average photon number of 0.1. The interference contrast achieved 96.52%, the average quantum bit error rate was 1.19%, and the raw key rate reached 88Kbps. Our experimental results demonstrate the feasibility and stability of the proposed phase-encoded semi-quantum key distribution system. Furthermore, by leveraging the "selective modulation" scheme proposed in this paper, we develop a comprehensive theoretical description of selective modulation. Through an analysis of quantum state evolution, we assess the security of our system, ultimately demonstrating its resilience against attacks targeting quantum states. The classical user of our system requires only two optical devices, significantly reducing the equipment requirements and enhancing its application potential. This work validates the feasibility of semi-quantum key distribution experiments and provides ideas for future research on semi-quantum key distribution experiments and security studies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07469v1-abstract-full').style.display = 'none'; document.getElementById('2405.07469v1-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 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/2405.07462">arXiv:2405.07462</a> <span> [<a href="https://arxiv.org/pdf/2405.07462">pdf</a>, <a href="https://arxiv.org/format/2405.07462">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Feynman Paradox about the Josephson effect and a sawtooth current in the double junction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhi-Lei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Qiao%2C+G">Guo-Jian Qiao</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+C+P">C. P. Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.07462v2-abstract-short" style="display: inline;"> We revisit the Feynman approach to the Josephson effect, which employs a pair of linear coupling equations for its modeling. It is found that while the exact solutions can account for the AC Josephson effect when the coupling strength is significantly less than the voltage, they fail to produce the DC Josephson effect in any practical scenario. To address this fundamental discrepancy, we derive th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07462v2-abstract-full').style.display = 'inline'; document.getElementById('2405.07462v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.07462v2-abstract-full" style="display: none;"> We revisit the Feynman approach to the Josephson effect, which employs a pair of linear coupling equations for its modeling. It is found that while the exact solutions can account for the AC Josephson effect when the coupling strength is significantly less than the voltage, they fail to produce the DC Josephson effect in any practical scenario. To address this fundamental discrepancy, we derive the coupled Ginzburg-Landau (GL) equations for two interconnected superconductors based on BCS theory. These equations reveal that the nonlinear coupling, which is overlooked in the Feynman method, is crucial in describing the spontaneous symmetry breaking in superconductors, a critical factor for achieving the DC Josephson effect. When the coupled GL equations are applied to a double junction, a sawtooth current pattern emerges, a result unattainable via the Feynman approach. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07462v2-abstract-full').style.display = 'none'; document.getElementById('2405.07462v2-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 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">9 pages, 3 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.06255">arXiv:2405.06255</a> <span> [<a href="https://arxiv.org/pdf/2405.06255">pdf</a>, <a href="https://arxiv.org/ps/2405.06255">ps</a>, <a href="https://arxiv.org/format/2405.06255">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"> Sharing Asymmetric Einstein-Podolsky-Rosen Steering with Projective Measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Rong%2C+Y">Yan-Xin Rong</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Shuo Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhen-Fei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Gu%2C+Y">Yong-Jian Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+Y">Ya Xiao</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="2405.06255v1-abstract-short" style="display: inline;"> Recently, both global and local classical randomness-assisted projective measurement protocols have been employed to share Bell nonlocality of an entangled state among multiple sequential parties. Unlike Bell nonlocality, Einstein-Podolsky-Rosen (EPR) steering exhibits distinct asymmetric characteristics and serves as the necessary quantum resource for one-sided device-independent quantum informat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.06255v1-abstract-full').style.display = 'inline'; document.getElementById('2405.06255v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.06255v1-abstract-full" style="display: none;"> Recently, both global and local classical randomness-assisted projective measurement protocols have been employed to share Bell nonlocality of an entangled state among multiple sequential parties. Unlike Bell nonlocality, Einstein-Podolsky-Rosen (EPR) steering exhibits distinct asymmetric characteristics and serves as the necessary quantum resource for one-sided device-independent quantum information tasks. In this work, we propose a projective measurement protocol and investigate the shareability of EPR steering with steering radius criterion theoretically and experimentally. Our results reveal that arbitrarily many independent parties can share one-way steerability using projective measurements, even when no shared randomness is available. Furthermore, by leveraging only local randomness, asymmetric two-way steerability can also be shared. Our work not only deepens the understanding of the role of projective measurements in sharing quantum correlations but also opens up a new avenue for reutilizing asymmetric quantum correlations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.06255v1-abstract-full').style.display = 'none'; document.getElementById('2405.06255v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 May, 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">13 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/2405.05965">arXiv:2405.05965</a> <span> [<a href="https://arxiv.org/pdf/2405.05965">pdf</a>, <a href="https://arxiv.org/format/2405.05965">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Quantum Communication and Mixed-State Order in Decohered Symmetry-Protected Topological States </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhehao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Agrawal%2C+U">Utkarsh Agrawal</a>, <a href="/search/quant-ph?searchtype=author&query=Vijay%2C+S">Sagar Vijay</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="2405.05965v1-abstract-short" style="display: inline;"> Certain pure-state symmetry-protected topological orders (SPT) can be used as a resource for transmitting quantum information. Here, we investigate the ability to transmit quantum information using decohered SPT states, and relate this property to the "strange correlation functions" which diagnose quantum many-body orders in these mixed-states. This perspective leads to the identification of a cla… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.05965v1-abstract-full').style.display = 'inline'; document.getElementById('2405.05965v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.05965v1-abstract-full" style="display: none;"> Certain pure-state symmetry-protected topological orders (SPT) can be used as a resource for transmitting quantum information. Here, we investigate the ability to transmit quantum information using decohered SPT states, and relate this property to the "strange correlation functions" which diagnose quantum many-body orders in these mixed-states. This perspective leads to the identification of a class of quantum channels -- termed symmetry-decoupling channels -- which do not necessarily preserve any weak or strong symmetries of the SPT state, but nevertheless protect quantum many-body order in the decohered mixed-state. We quantify the ability to transmit quantum information in decohered SPT states through the coherent quantum information, whose behavior is generally related to a decoding problem, whereby local measurements in the system are used to attempt to "learn" the symmetry charge of the SPT state before decoherence. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.05965v1-abstract-full').style.display = 'none'; document.getElementById('2405.05965v1-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 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">27 pages, 8 figures</span> </p> </li> </ol> <nav class="pagination is-small is-centered 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