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name="searchtype"><option value="all">All fields</option><option value="title">Title</option><option selected value="author">Author(s)</option><option value="abstract">Abstract</option><option value="comments">Comments</option><option value="journal_ref">Journal reference</option><option value="acm_class">ACM classification</option><option value="msc_class">MSC classification</option><option value="report_num">Report number</option><option value="paper_id">arXiv identifier</option><option value="doi">DOI</option><option value="orcid">ORCID</option><option value="license">License (URI)</option><option value="author_id">arXiv author ID</option><option value="help">Help pages</option><option value="full_text">Full text</option></select> <input id="query" name="query" type="text" value="Cao, S"> <ul id="abstracts"><li><input checked id="abstracts-0" name="abstracts" type="radio" value="show"> <label for="abstracts-0">Show abstracts</label></li><li><input id="abstracts-1" name="abstracts" 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is-link">Go</button> </div> </div> </form> </div> </div> <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/2410.10416">arXiv:2410.10416</a> <span> [<a href="https://arxiv.org/pdf/2410.10416">pdf</a>, <a href="https://arxiv.org/ps/2410.10416">ps</a>, <a href="https://arxiv.org/format/2410.10416">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"> Complementing the transmon by integrating a geometric shunt inductor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Fasciati%2C+S+D">Simone D. Fasciati</a>, <a href="/search/quant-ph?searchtype=author&query=Shteynas%2C+B">Boris Shteynas</a>, <a href="/search/quant-ph?searchtype=author&query=Campanaro%2C+G">Giulio Campanaro</a>, <a href="/search/quant-ph?searchtype=author&query=Bakr%2C+M">Mustafa Bakr</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Chidambaram%2C+V">Vivek Chidambaram</a>, <a href="/search/quant-ph?searchtype=author&query=Wills%2C+J">James Wills</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P+J">Peter J. Leek</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="2410.10416v1-abstract-short" style="display: inline;"> We realize a single-Josephson-junction transmon qubit shunted by a simple geometric inductor. We couple it capacitively to a conventional transmon and show that the ZZ interaction between the two qubits is completely suppressed when they are flux-biased to have opposite-sign anharmonicities. Away from the flux sweet spot of the inductively-shunted transmon, we demonstrate fast two-qubit interactio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.10416v1-abstract-full').style.display = 'inline'; document.getElementById('2410.10416v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.10416v1-abstract-full" style="display: none;"> We realize a single-Josephson-junction transmon qubit shunted by a simple geometric inductor. We couple it capacitively to a conventional transmon and show that the ZZ interaction between the two qubits is completely suppressed when they are flux-biased to have opposite-sign anharmonicities. Away from the flux sweet spot of the inductively-shunted transmon, we demonstrate fast two-qubit interactions using first-order sideband transitions. The simplicity of this two-qubit-species circuit makes it promising for building large lattices of superconducting qubits with low coherent error and a rich gate set. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.10416v1-abstract-full').style.display = 'none'; document.getElementById('2410.10416v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.09055">arXiv:2408.09055</a> <span> [<a href="https://arxiv.org/pdf/2408.09055">pdf</a>, <a href="https://arxiv.org/format/2408.09055">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Distributed, Parallel, and Cluster Computing">cs.DC</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"> Atlas: Hierarchical Partitioning for Quantum Circuit Simulation on GPUs (Extended Version) </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+M">Mingkuan Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shiyi Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Miao%2C+X">Xupeng Miao</a>, <a href="/search/quant-ph?searchtype=author&query=Acar%2C+U+A">Umut A. Acar</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+Z">Zhihao Jia</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="2408.09055v2-abstract-short" style="display: inline;"> This paper presents techniques for theoretically and practically efficient and scalable Schr枚dinger-style quantum circuit simulation. Our approach partitions a quantum circuit into a hierarchy of subcircuits and simulates the subcircuits on multi-node GPUs, exploiting available data parallelism while minimizing communication costs. To minimize communication costs, we formulate an Integer Linear Pr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.09055v2-abstract-full').style.display = 'inline'; document.getElementById('2408.09055v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.09055v2-abstract-full" style="display: none;"> This paper presents techniques for theoretically and practically efficient and scalable Schr枚dinger-style quantum circuit simulation. Our approach partitions a quantum circuit into a hierarchy of subcircuits and simulates the subcircuits on multi-node GPUs, exploiting available data parallelism while minimizing communication costs. To minimize communication costs, we formulate an Integer Linear Program that rewards simulation of "nearby" gates on "nearby" GPUs. To maximize throughput, we use a dynamic programming algorithm to compute the subcircuit simulated by each kernel at a GPU. We realize these techniques in Atlas, a distributed, multi-GPU quantum circuit simulator. Our evaluation on a variety of quantum circuits shows that Atlas outperforms state-of-the-art GPU-based simulators by more than 2$\times$ on average and is able to run larger circuits via offloading to DRAM, outperforming other large-circuit simulators by two orders of magnitude. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.09055v2-abstract-full').style.display = 'none'; document.getElementById('2408.09055v2-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 37 figures, extended version of the paper presented in SC24</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.08460">arXiv:2408.08460</a> <span> [<a href="https://arxiv.org/pdf/2408.08460">pdf</a>, <a href="https://arxiv.org/ps/2408.08460">ps</a>, <a href="https://arxiv.org/format/2408.08460">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> </div> </div> <p class="title is-5 mathjax"> Field mixing in a thermal medium: A quantum master equation approach </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuyang Cao</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="2408.08460v2-abstract-short" style="display: inline;"> We studied the nonequilibrium dynamics of the indirect mixing of two (pseudo-)scalar fields induced by their couplings to common decay channels in a medium. The effective non-Markovian quantum master equation (QME) for the two fields' reduced density matrix is derived to leading order in the couplings of the two fields with the medium, but to all orders of the couplings among degrees of freedom in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08460v2-abstract-full').style.display = 'inline'; document.getElementById('2408.08460v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.08460v2-abstract-full" style="display: none;"> We studied the nonequilibrium dynamics of the indirect mixing of two (pseudo-)scalar fields induced by their couplings to common decay channels in a medium. The effective non-Markovian quantum master equation (QME) for the two fields' reduced density matrix is derived to leading order in the couplings of the two fields with the medium, but to all orders of the couplings among degrees of freedom in the medium. The self-energy and noise-kernel in the QME satisfy a fluctuation-dissipation relation. The solutions show that an initial expectation value (condensate) of one field induces a condensate of the other field through the indirect mixing and that the populations and coherence of the two fields thermalize and approach to non-vanishing values asymptotically. The nearly-degenerate field masses and coupling strengths resonantly enhance the quantum beats and asymptotic coherence, and induce a prominent dynamics of the vacuum after the switch-on of the couplings. We argue that a time-dependent definitions of particles due to the changing vacuum must be introduced so as to obtain results consistent with the calculations of equilibrium states in the asymptotic limit. A coupling strength hierarchy breaks down the resonant enhancement in the nearly-degenerate case but leads to different power countings of the coupling strengths in the magnitudes of the observables and time-scales in the evolution, suggesting the possibility of detecting extremely long-lived particles using prepared short-lived particles within a practical experimental period. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08460v2-abstract-full').style.display = 'none'; document.getElementById('2408.08460v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 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">69 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/2407.21415">arXiv:2407.21415</a> <span> [<a href="https://arxiv.org/pdf/2407.21415">pdf</a>, <a href="https://arxiv.org/format/2407.21415">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"> In situ Qubit Frequency Tuning Circuit for Scalable Superconducting Quantum Computing: Scheme and Experiment </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Lei Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+Z">Zhiguang Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+M">Ming Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Rong%2C+T">Tao Rong</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+C">Chenyin Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+T">Tianzuo Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+T">Tao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+H">Hui Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Zha%2C+C">Chen Zha</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fusheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Q">Qingling Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Y">Yangsen Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Rong%2C+H">Hao Rong</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+K">Kai Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Sirui Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shaojun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+H">Haoran Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+Y">Yisen Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yulin Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuhuai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+G">Gang Wu</a> , et al. (8 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.21415v1-abstract-short" style="display: inline;"> Frequency tunable qubit plays a significant role for scalable superconducting quantum processors. The state-of-the-art room-temperature electronics for tuning qubit frequency suffers from unscalable limit, such as heating problem, linear growth of control cables, etc. Here we propose a scalable scheme to tune the qubit frequency by using in situ superconducting circuit, which is based on radio fre… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.21415v1-abstract-full').style.display = 'inline'; document.getElementById('2407.21415v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.21415v1-abstract-full" style="display: none;"> Frequency tunable qubit plays a significant role for scalable superconducting quantum processors. The state-of-the-art room-temperature electronics for tuning qubit frequency suffers from unscalable limit, such as heating problem, linear growth of control cables, etc. Here we propose a scalable scheme to tune the qubit frequency by using in situ superconducting circuit, which is based on radio frequency superconducting quantum interference device (rf-SQUID). We demonstrate both theoretically and experimentally that the qubit frequency could be modulated by inputting several single pulses into rf-SQUID. Compared with the traditional scheme, our scheme not only solves the heating problem, but also provides the potential to exponentially reduce the number of cables inside the dilute refrigerator and the room-temperature electronics resource for tuning qubit frequency, which is achieved by a time-division-multiplex (TDM) scheme combining rf-SQUID with switch arrays. With such TDM scheme, the number of cables could be reduced from the usual $\sim 3n$ to $\sim \log_2{(3n)} + 1$ for two-dimensional quantum processors comprising $n$ qubits and $\sim 2n$ couplers. Our work paves the way for large-scale control of superconducting quantum processor. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.21415v1-abstract-full').style.display = 'none'; document.getElementById('2407.21415v1-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 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">9 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/2405.00478">arXiv:2405.00478</a> <span> [<a href="https://arxiv.org/pdf/2405.00478">pdf</a>, <a href="https://arxiv.org/ps/2405.00478">ps</a>, <a href="https://arxiv.org/format/2405.00478">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="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"> Dual-frequency optical-microwave atomic clocks based on cesium atoms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Shi%2C+T">Tiantian Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+Q">Qiang Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+X">Xiaomin Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Z">Zhenfeng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+K">Kunkun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shiying Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+H">Hangbo Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Z">Zijie Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jingbiao 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="2405.00478v1-abstract-short" style="display: inline;"> $^{133}$Cs, which is the only stable cesium (Cs) isotope, is one of the most investigated elements in atomic spectroscopy and was used to realize the atomic clock in 1955. Among all atomic clocks, the cesium atomic clock has a special place, since the current unit of time is based on a microwave transition in the Cs atom. In addition, the long lifetime of the $6{\text{P}}_{3/2}… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.00478v1-abstract-full').style.display = 'inline'; document.getElementById('2405.00478v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.00478v1-abstract-full" style="display: none;"> $^{133}$Cs, which is the only stable cesium (Cs) isotope, is one of the most investigated elements in atomic spectroscopy and was used to realize the atomic clock in 1955. Among all atomic clocks, the cesium atomic clock has a special place, since the current unit of time is based on a microwave transition in the Cs atom. In addition, the long lifetime of the $6{\text{P}}_{3/2}$ state and simple preparation technique of Cs vapor cells have great relevance to quantum and atom optics experiments, which suggests the use of the $6{\text{S}} - 6{\text{P}}$ D2 transition as an optical frequency standard. In this work, using one laser as the local oscillator and Cs atoms as the quantum reference, we realized two atomic clocks in the optical and microwave frequencies, respectively. Both clocks could be freely switched or simultaneously output. The optical clock based on the vapor cell continuously operated with a frequency stability of $3.89 \times {10^{ - 13}}$ at 1 s, decreasing to $2.17 \times {10^{ - 13}}$ at 32 s, which was frequency stabilized by modulation transfer spectroscopy and estimated by an optical comb. Then, applying this stabilized laser for an optically pumped Cs beam atomic clock to reduce the laser frequency noise, we obtained a microwave clock with a frequency stability of $1.84 \times {10^{ - 12}}/\sqrt 蟿$, reaching $5.99 \times {10^{ - 15}}$ at $10^5$ s. This study demonstrates an attractive feature for the commercialization and deployment of optical and microwave clocks and will guide further development of integrated atomic clocks with better stability. Thus, this study lays the groundwork for future quantum metrology and laser physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.00478v1-abstract-full').style.display = 'none'; document.getElementById('2405.00478v1-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 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">8 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/2403.07084">arXiv:2403.07084</a> <span> [<a href="https://arxiv.org/pdf/2403.07084">pdf</a>, <a href="https://arxiv.org/ps/2403.07084">ps</a>, <a href="https://arxiv.org/format/2403.07084">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</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 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/PhysRevD.109.105021">10.1103/PhysRevD.109.105021 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Is the effective potential, effective for dynamics? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Herring%2C+N">Nathan Herring</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuyang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Boyanovsky%2C+D">Daniel Boyanovsky</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.07084v2-abstract-short" style="display: inline;"> We critically examine the applicability of the effective potential within dynamical situations and find, in short, that the answer is negative. An important caveat of the use of an effective potential in dynamical equations of motion is an explicit violation of energy conservation. An \emph{adiabatic} effective potential is introduced in a consistent quasi-static approximation, and its narrow re… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.07084v2-abstract-full').style.display = 'inline'; document.getElementById('2403.07084v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.07084v2-abstract-full" style="display: none;"> We critically examine the applicability of the effective potential within dynamical situations and find, in short, that the answer is negative. An important caveat of the use of an effective potential in dynamical equations of motion is an explicit violation of energy conservation. An \emph{adiabatic} effective potential is introduced in a consistent quasi-static approximation, and its narrow regime of validity is discussed. Two ubiquitous instances in which even the adiabatic effective potential is not valid in dynamics are studied in detail: parametric amplification in the case of oscillating mean fields, and spinodal instabilities associated with spontaneous symmetry breaking. In both cases profuse particle production is directly linked to the failure of the effective potential to describe the dynamics. We introduce a consistent, renormalized, energy conserving dynamical framework that is amenable to numerical implementation. Energy conservation leads to the emergence of asymptotic highly excited, entangled stationary states from the dynamical evolution. As a corollary, decoherence via dephasing of the density matrix in the adiabatic basis is argued to lead to an emergent entropy, formally equivalent to the entanglement entropy. The results suggest novel characterization of asymptotic equilibrium states in terms of order parameter vs. energy density. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.07084v2-abstract-full').style.display = 'none'; document.getElementById('2403.07084v2-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">v1</span> submitted 11 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">51 pages, 5 figures, more references and discussions</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. D 109, 105021 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.09532">arXiv:2402.09532</a> <span> [<a href="https://arxiv.org/pdf/2402.09532">pdf</a>, <a href="https://arxiv.org/format/2402.09532">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 state discrimination enhanced by path signature </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Shao%2C+Z">Zhen Shao</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+J">Jian-Qing Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Alghadeer%2C+M">Mohammed Alghadeer</a>, <a href="/search/quant-ph?searchtype=author&query=Fasciati%2C+S+D">Simone D Fasciati</a>, <a href="/search/quant-ph?searchtype=author&query=Piscitelli%2C+M">Michele Piscitelli</a>, <a href="/search/quant-ph?searchtype=author&query=Taravati%2C+S">Sajjad Taravati</a>, <a href="/search/quant-ph?searchtype=author&query=Bakr%2C+M">Mustafa Bakr</a>, <a href="/search/quant-ph?searchtype=author&query=Lyons%2C+T">Terry Lyons</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P">Peter Leek</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.09532v1-abstract-short" style="display: inline;"> Quantum state discrimination plays an essential role in quantum technology, crucial for quantum error correction, metrology, and sensing. While conventional methods rely on integrating readout signals or classifying raw signals, we developed a method to extract information about state transitions during readout, based on the path signature method, a tool for analyzing stochastic time series. The h… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.09532v1-abstract-full').style.display = 'inline'; document.getElementById('2402.09532v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.09532v1-abstract-full" style="display: none;"> Quantum state discrimination plays an essential role in quantum technology, crucial for quantum error correction, metrology, and sensing. While conventional methods rely on integrating readout signals or classifying raw signals, we developed a method to extract information about state transitions during readout, based on the path signature method, a tool for analyzing stochastic time series. The hardware experiments demonstrate an improvement in transmon qutrit state readout fidelity from 85.9 $\pm$ 1.0% to 91.0 $\pm$ 0.5%, without the need for additional hardware. This method has the potential to become a foundational tool for quantum technology. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.09532v1-abstract-full').style.display = 'none'; document.getElementById('2402.09532v1-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 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.01873">arXiv:2401.01873</a> <span> [<a href="https://arxiv.org/pdf/2401.01873">pdf</a>, <a href="https://arxiv.org/format/2401.01873">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Observation of the Magnonic Dicke Superradiant Phase Transition </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kim%2C+D">Dasom Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Dasgupta%2C+S">Sohail Dasgupta</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiaoxuan Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Park%2C+J">Joong-Mok Park</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+H">Hao-Tian Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+L">Liang Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Doumani%2C+J">Jacques Doumani</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xinwei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+W">Wanting Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+D">Di Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+R+H+J">Richard H. J. Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Everitt%2C+H+O">Henry O. Everitt</a>, <a href="/search/quant-ph?searchtype=author&query=Kimura%2C+S">Shojiro Kimura</a>, <a href="/search/quant-ph?searchtype=author&query=Nojiri%2C+H">Hiroyuki Nojiri</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Jigang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shixun Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Bamba%2C+M">Motoaki Bamba</a>, <a href="/search/quant-ph?searchtype=author&query=Hazzard%2C+K+R+A">Kaden R. A. Hazzard</a>, <a href="/search/quant-ph?searchtype=author&query=Kono%2C+J">Junichiro Kono</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.01873v1-abstract-short" style="display: inline;"> Two-level atoms coupled with single-mode cavity photons are predicted to exhibit a quantum phase transition when the coupling strength exceeds a critical value, entering a phase in which atomic polarization and photonic field are finite even at zero temperature and without external driving. However, this phenomenon, the superradiant phase transition (SRPT), is forbidden by a no-go theorem due to t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.01873v1-abstract-full').style.display = 'inline'; document.getElementById('2401.01873v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.01873v1-abstract-full" style="display: none;"> Two-level atoms coupled with single-mode cavity photons are predicted to exhibit a quantum phase transition when the coupling strength exceeds a critical value, entering a phase in which atomic polarization and photonic field are finite even at zero temperature and without external driving. However, this phenomenon, the superradiant phase transition (SRPT), is forbidden by a no-go theorem due to the existence of the diamagnetic term in the Hamiltonian. Here, we present spectroscopic evidence for a magnonic SRPT in ErFeO$_3$, where the role of the photonic mode (two-level atoms) in the photonic SRPT is played by an Fe$^{3+}$ magnon mode (Er$^{3+}$ spins). The absence of the diamagnetic term in the Fe$^{3+}$-Er$^{3+}$ exchange coupling ensures that the no-go theorem does not apply. Terahertz and gigahertz magnetospectroscopy experiments revealed the signatures of the SRPT -- a kink and a softening, respectively, of two spin-magnon hybridized modes at the critical point. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.01873v1-abstract-full').style.display = 'none'; document.getElementById('2401.01873v1-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.15534">arXiv:2311.15534</a> <span> [<a href="https://arxiv.org/pdf/2311.15534">pdf</a>, <a href="https://arxiv.org/format/2311.15534">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"> Analogue of collectively induced transparency in metamaterials </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+W">Wei Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shi-Ting Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Qu%2C+X">Xiaowei Qu</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+S">Shan Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wentao 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="2311.15534v1-abstract-short" style="display: inline;"> Most recently, a brand new optical phenomenon, collectively induced transparency (CIT) has already been proposed in the cavity quantum electrodynamics system, which comes from the coupling between the cavity and ions and the quantum interference of collective ions. Due to the equivalent analogue of quantum optics, metamaterial also is a good platform to realize collectively induced transparency (C… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.15534v1-abstract-full').style.display = 'inline'; document.getElementById('2311.15534v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.15534v1-abstract-full" style="display: none;"> Most recently, a brand new optical phenomenon, collectively induced transparency (CIT) has already been proposed in the cavity quantum electrodynamics system, which comes from the coupling between the cavity and ions and the quantum interference of collective ions. Due to the equivalent analogue of quantum optics, metamaterial also is a good platform to realize collectively induced transparency (CIT) which can be useful for highly sensitive metamaterial sensors, optical switches and photo-memory. In this paper, we propose the coupling of bright mode and interference of dark modes, to realize the CIT in terahertz (THz) metamaterial system. We give the theoretical analysis, analytical solutions, simulations and experiments to demonstrate our idea. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.15534v1-abstract-full').style.display = 'none'; document.getElementById('2311.15534v1-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 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.17070">arXiv:2310.17070</a> <span> [<a href="https://arxiv.org/pdf/2310.17070">pdf</a>, <a href="https://arxiv.org/ps/2310.17070">ps</a>, <a href="https://arxiv.org/format/2310.17070">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="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 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/PhysRevD.109.036038">10.1103/PhysRevD.109.036038 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Effective field theory of particle mixing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuyang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Boyanovsky%2C+D">Daniel Boyanovsky</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.17070v2-abstract-short" style="display: inline;"> We introduce an effective field theory to study \emph{indirect} mixing of two fields induced by their couplings to a common decay channel in a medium. The extension of the method of Lee, Oehme and Yang, the cornerstone of analysis of CP violation in flavored mesons, to include mixing of particles with different masses provides a guide to and benchmark for the effective field theory. The analysis r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.17070v2-abstract-full').style.display = 'inline'; document.getElementById('2310.17070v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.17070v2-abstract-full" style="display: none;"> We introduce an effective field theory to study \emph{indirect} mixing of two fields induced by their couplings to a common decay channel in a medium. The extension of the method of Lee, Oehme and Yang, the cornerstone of analysis of CP violation in flavored mesons, to include mixing of particles with different masses provides a guide to and benchmark for the effective field theory. The analysis reveals subtle caveats in the description of mixing in terms of the widely used non-Hermitian effective Hamiltonian, more acute in the non-degenerate case. The effective field theory describes the dynamics of field mixing where the common intermediate states populate a bath in thermal equilibrium, as an \emph{open quantum system}. We obtain the effective action up to second order in the couplings, where indirect mixing is a consequence of off-diagonal self-energy components. We find that if only one of the mixing fields features an initial expectation value, indirect mixing induces an expectation value of the other field. The equal time two point correlation functions exhibit asymptotic approach to a stationary thermal state, and the emergence of long-lived \emph{bath induced} coherence which display quantum beats as a consequence of interference of quasinormal modes in the medium. The amplitudes of the quantum beats are resonantly enhanced in the nearly degenerate case with potential observational consequences. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.17070v2-abstract-full').style.display = 'none'; document.getElementById('2310.17070v2-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 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.13036">arXiv:2309.13036</a> <span> [<a href="https://arxiv.org/pdf/2309.13036">pdf</a>, <a href="https://arxiv.org/format/2309.13036">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"> Encoding optimization for quantum machine learning demonstrated on a superconducting transmon qutrit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weixi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Tilly%2C+J">Jules Tilly</a>, <a href="/search/quant-ph?searchtype=author&query=Agarwal%2C+A">Abhishek Agarwal</a>, <a href="/search/quant-ph?searchtype=author&query=Bakr%2C+M">Mustafa Bakr</a>, <a href="/search/quant-ph?searchtype=author&query=Campanaro%2C+G">Giulio Campanaro</a>, <a href="/search/quant-ph?searchtype=author&query=Fasciati%2C+S+D">Simone D Fasciati</a>, <a href="/search/quant-ph?searchtype=author&query=Wills%2C+J">James Wills</a>, <a href="/search/quant-ph?searchtype=author&query=Shteynas%2C+B">Boris Shteynas</a>, <a href="/search/quant-ph?searchtype=author&query=Chidambaram%2C+V">Vivek Chidambaram</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P">Peter Leek</a>, <a href="/search/quant-ph?searchtype=author&query=Rungger%2C+I">Ivan Rungger</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2309.13036v1-abstract-short" style="display: inline;"> Qutrits, three-level quantum systems, have the advantage of potentially requiring fewer components than the typically used two-level qubits to construct equivalent quantum circuits. This work investigates the potential of qutrit parametric circuits in machine learning classification applications. We propose and evaluate different data-encoding schemes for qutrits, and find that the classification… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.13036v1-abstract-full').style.display = 'inline'; document.getElementById('2309.13036v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.13036v1-abstract-full" style="display: none;"> Qutrits, three-level quantum systems, have the advantage of potentially requiring fewer components than the typically used two-level qubits to construct equivalent quantum circuits. This work investigates the potential of qutrit parametric circuits in machine learning classification applications. We propose and evaluate different data-encoding schemes for qutrits, and find that the classification accuracy varies significantly depending on the used encoding. We therefore propose a training method for encoding optimization that allows to consistently achieve high classification accuracy. Our theoretical analysis and numerical simulations indicate that the qutrit classifier can achieve high classification accuracy using fewer components than a comparable qubit system. We showcase the qutrit classification using the optimized encoding method on superconducting transmon qutrits, demonstrating the practicality of the proposed method on noisy hardware. Our work demonstrates high-precision ternary classification using fewer circuit elements, establishing qutrit parametric quantum circuits as a viable and efficient tool for quantum machine learning applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.13036v1-abstract-full').style.display = 'none'; document.getElementById('2309.13036v1-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 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.15972">arXiv:2305.15972</a> <span> [<a href="https://arxiv.org/pdf/2305.15972">pdf</a>, <a href="https://arxiv.org/format/2305.15972">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"> Logical Magic State Preparation with Fidelity Beyond the Distillation Threshold on a Superconducting Quantum Processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Y">Yangsen Ye</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+T">Tan He</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">He-Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+Z">Zuolin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yiming Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Youwei Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+D">Dachao Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Q">Qingling Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+H">Huijie Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Sirui Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fusheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chung%2C+T">Tung-Hsun Chung</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+H">Hui Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+D">Daojin Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+M">Ming Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+C">Cheng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shaojun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+L">Lianchen Han</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+N">Na Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+F">Futian Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+H">Haoran Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Rong%2C+H">Hao Rong</a> , et al. (13 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.15972v2-abstract-short" style="display: inline;"> Fault-tolerant quantum computing based on surface code has emerged as an attractive candidate for practical large-scale quantum computers to achieve robust noise resistance. To achieve universality, magic states preparation is a commonly approach for introducing non-Clifford gates. Here, we present a hardware-efficient and scalable protocol for arbitrary logical state preparation for the rotated s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.15972v2-abstract-full').style.display = 'inline'; document.getElementById('2305.15972v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.15972v2-abstract-full" style="display: none;"> Fault-tolerant quantum computing based on surface code has emerged as an attractive candidate for practical large-scale quantum computers to achieve robust noise resistance. To achieve universality, magic states preparation is a commonly approach for introducing non-Clifford gates. Here, we present a hardware-efficient and scalable protocol for arbitrary logical state preparation for the rotated surface code, and further experimentally implement it on the \textit{Zuchongzhi} 2.1 superconducting quantum processor. An average of \hhl{$0.8983 \pm 0.0002$} logical fidelity at different logical states with distance-three is achieved, \hhl{taking into account both state preparation and measurement errors.} In particular, \hhl{the magic states $|A^{蟺/4}\rangle_L$, $|H\rangle_L$, and $|T\rangle_L$ are prepared non-destructively with logical fidelities of $0.8771 \pm 0.0009 $, $0.9090 \pm 0.0009 $, and $0.8890 \pm 0.0010$, respectively, which are higher than the state distillation protocol threshold, 0.859 (for H-type magic state) and 0.827 (for T -type magic state).} Our work provides a viable and efficient avenue for generating high-fidelity raw logical magic states, which is essential for realizing non-Clifford logical gates in the surface code. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.15972v2-abstract-full').style.display = 'none'; document.getElementById('2305.15972v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">In this version, we do not employ readout error mitigation strategies (in the previous version, we use readout transition matrix to mitigate the measurement error) to remove measurement errors because we believe it provides a more predictive assessment of the actual fidelity when generating and consuming magic states for a non-Clifford gate, as consuming the state involves measurement</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.08296">arXiv:2304.08296</a> <span> [<a href="https://arxiv.org/pdf/2304.08296">pdf</a>, <a href="https://arxiv.org/ps/2304.08296">ps</a>, <a href="https://arxiv.org/format/2304.08296">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"> Modes mismatch induced variation of quantum coherence for two-mode localized Gaussian states in accelerated frame </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gong%2C+X">Xiaolong Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+Y">Yue Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tonghua Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuo Cao</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.08296v1-abstract-short" style="display: inline;"> Quantum coherence is the basic concept of superposition of quantum states and plays an important role in quantum metrology. We show how a pair of uniformly accelerated observers with a local two-mode Gaussian quantum state affects the Gaussian quantum coherence. We find that the quantum coherence decreases with increasing acceleration, which is due to the Unruh effect that destroys the quantum res… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.08296v1-abstract-full').style.display = 'inline'; document.getElementById('2304.08296v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.08296v1-abstract-full" style="display: none;"> Quantum coherence is the basic concept of superposition of quantum states and plays an important role in quantum metrology. We show how a pair of uniformly accelerated observers with a local two-mode Gaussian quantum state affects the Gaussian quantum coherence. We find that the quantum coherence decreases with increasing acceleration, which is due to the Unruh effect that destroys the quantum resource. Essentially, the variation of quantum coherence is caused by the modes mismatch between the input and output mode. Through 2000 randomly generated states, we demonstrate that such mismatch is dominated by the acceleration effect and mildly affected by the waveform parameters. Moreover, the squeezing parameter acted as a suppressor of the reduced coherence, but it tended to be invalid in the high squeezing. In addition, the squeezing parameter can act as a suppressor of the reduced coherence, but the effect of the squeezing parameter tends to be ineffective under high squeezing conditions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.08296v1-abstract-full').style.display = 'none'; document.getElementById('2304.08296v1-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 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 5 figures, accepted for publication in The European Physical Journal Plus</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.04796">arXiv:2303.04796</a> <span> [<a href="https://arxiv.org/pdf/2303.04796">pdf</a>, <a href="https://arxiv.org/format/2303.04796">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/2058-9565/ad37d4">10.1088/2058-9565/ad37d4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Emulating two qubits with a four-level transmon qudit for variational quantum algorithms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Bakr%2C+M">Mustafa Bakr</a>, <a href="/search/quant-ph?searchtype=author&query=Campanaro%2C+G">Giulio Campanaro</a>, <a href="/search/quant-ph?searchtype=author&query=Fasciati%2C+S+D">Simone D. Fasciati</a>, <a href="/search/quant-ph?searchtype=author&query=Wills%2C+J">James Wills</a>, <a href="/search/quant-ph?searchtype=author&query=Lall%2C+D">Deep Lall</a>, <a href="/search/quant-ph?searchtype=author&query=Shteynas%2C+B">Boris Shteynas</a>, <a href="/search/quant-ph?searchtype=author&query=Chidambaram%2C+V">Vivek Chidambaram</a>, <a href="/search/quant-ph?searchtype=author&query=Rungger%2C+I">Ivan Rungger</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P">Peter Leek</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.04796v2-abstract-short" style="display: inline;"> Using quantum systems with more than two levels, or qudits, can scale the computation space of quantum processors more efficiently than using qubits, which may offer an easier physical implementation for larger Hilbert spaces. However, individual qudits may exhibit larger noise, and algorithms designed for qubits require to be recompiled to qudit algorithms for execution. In this work, we implemen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.04796v2-abstract-full').style.display = 'inline'; document.getElementById('2303.04796v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.04796v2-abstract-full" style="display: none;"> Using quantum systems with more than two levels, or qudits, can scale the computation space of quantum processors more efficiently than using qubits, which may offer an easier physical implementation for larger Hilbert spaces. However, individual qudits may exhibit larger noise, and algorithms designed for qubits require to be recompiled to qudit algorithms for execution. In this work, we implemented a two-qubit emulator using a 4-level superconducting transmon qudit for variational quantum algorithm applications and analyzed its noise model. The major source of error for the variational algorithm was readout misclassification error and amplitude damping. To improve the accuracy of the results, we applied error-mitigation techniques to reduce the effects of the misclassification and qudit decay event. The final predicted energy value is within the range of chemical accuracy. Our work demonstrates that qudits are a practical alternative to qubits for variational algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.04796v2-abstract-full').style.display = 'none'; document.getElementById('2303.04796v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.06028">arXiv:2302.06028</a> <span> [<a href="https://arxiv.org/pdf/2302.06028">pdf</a>, <a href="https://arxiv.org/format/2302.06028">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 Simulation of an Extended Dicke Model with a Magnetic Solid </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Peraca%2C+N+M">Nicolas Marquez Peraca</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xinwei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Moya%2C+J+M">Jaime M. Moya</a>, <a href="/search/quant-ph?searchtype=author&query=Hayashida%2C+K">Kenji Hayashida</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+D">Dasom Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiaoxuan Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Neubauer%2C+K+J">Kelly J. Neubauer</a>, <a href="/search/quant-ph?searchtype=author&query=Padilla%2C+D+F">Diego Fallas Padilla</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+C">Chien-Lung Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Dai%2C+P">Pengcheng Dai</a>, <a href="/search/quant-ph?searchtype=author&query=Nevidomskyy%2C+A+H">Andriy H. Nevidomskyy</a>, <a href="/search/quant-ph?searchtype=author&query=Pu%2C+H">Han Pu</a>, <a href="/search/quant-ph?searchtype=author&query=Morosan%2C+E">Emilia Morosan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shixun Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Bamba%2C+M">Motoaki Bamba</a>, <a href="/search/quant-ph?searchtype=author&query=Kono%2C+J">Junichiro Kono</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.06028v2-abstract-short" style="display: inline;"> The Dicke model describes the cooperative interaction of an ensemble of two-level atoms with a single-mode photonic field and exhibits a quantum phase transition as a function of light--matter coupling strength. Extending this model by incorporating short-range atom--atom interactions makes the problem intractable but is expected to produce new phases. Here, we simulate such an extended Dicke mode… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.06028v2-abstract-full').style.display = 'inline'; document.getElementById('2302.06028v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.06028v2-abstract-full" style="display: none;"> The Dicke model describes the cooperative interaction of an ensemble of two-level atoms with a single-mode photonic field and exhibits a quantum phase transition as a function of light--matter coupling strength. Extending this model by incorporating short-range atom--atom interactions makes the problem intractable but is expected to produce new phases. Here, we simulate such an extended Dicke model using a crystal of ErFeO$_3$, where the role of atoms (photons) is played by Er$^{3+}$ spins (Fe$^{3+}$ magnons). Through magnetocaloric effect and terahertz magnetospectroscopy measurements, we demonstrated the existence of a novel atomically ordered phase in addition to the superradiant and normal phases that are expected from the standard Dicke model. Further, we elucidated the nature of the phase boundaries in the temperature--magnetic-field phase diagram, identifying both first-order and second-order phase transitions. These results lay the foundation for studying multiatomic quantum optics models using well-characterized many-body condensed matter systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.06028v2-abstract-full').style.display = 'none'; document.getElementById('2302.06028v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.08006">arXiv:2212.08006</a> <span> [<a href="https://arxiv.org/pdf/2212.08006">pdf</a>, <a href="https://arxiv.org/format/2212.08006">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-024-02530-z">10.1038/s41567-024-02530-z <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental quantum computational chemistry with optimised unitary coupled cluster ansatz </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shaojun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+J">Jinzhao Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+H">Haoran Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+M">Ming Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yukun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fusheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Y">Yangsen Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yulin Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Sirui Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+K">Kun Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zha%2C+C">Chen Zha</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+C">Chong Ying</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Q">Qingling Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">He-Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Youwei Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Shiyu Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+J">Jiale Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+D">Daojin Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+D">Dachao Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+H">Hong Su</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+H">Hui Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Rong%2C+H">Hao Rong</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+K">Kaili Zhang</a> , et al. (13 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.08006v3-abstract-short" style="display: inline;"> Quantum computational chemistry has emerged as an important application of quantum computing. Hybrid quantum-classical computing methods, such as variational quantum eigensolvers (VQE), have been designed as promising solutions to quantum chemistry problems, yet challenges due to theoretical complexity and experimental imperfections hinder progress in achieving reliable and accurate results. Exper… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.08006v3-abstract-full').style.display = 'inline'; document.getElementById('2212.08006v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.08006v3-abstract-full" style="display: none;"> Quantum computational chemistry has emerged as an important application of quantum computing. Hybrid quantum-classical computing methods, such as variational quantum eigensolvers (VQE), have been designed as promising solutions to quantum chemistry problems, yet challenges due to theoretical complexity and experimental imperfections hinder progress in achieving reliable and accurate results. Experimental works for solving electronic structures are consequently still restricted to nonscalable (hardware efficient) or classically simulable (Hartree-Fock) ansatz, or limited to a few qubits with large errors. The experimental realisation of scalable and high-precision quantum chemistry simulation remains elusive. Here, we address the critical challenges {associated with} solving molecular electronic structures using noisy quantum processors. Our protocol presents significant improvements in the circuit depth and running time, key metrics for chemistry simulation. Through systematic hardware enhancements and the integration of error mitigation techniques, we push forward the limit of experimental quantum computational chemistry and successfully scale up the implementation of VQE with an optimised unitary coupled-cluster ansatz to 12 qubits. We produce high-precision results of the ground-state energy for molecules with error suppression by around two orders of magnitude. We achieve chemical accuracy for H$_2$ at all bond distances and LiH at small bond distances in the experiment, even beyond the two recent concurrent works. Our work demonstrates a feasible path towards a scalable solution to electronic structure calculation, validating the key technological features and identifying future challenges for this goal. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.08006v3-abstract-full').style.display = 'none'; document.getElementById('2212.08006v3-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">v1</span> submitted 15 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 4 figures in the main text, and 29 pages supplementary materials with 17 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.05161">arXiv:2212.05161</a> <span> [<a href="https://arxiv.org/pdf/2212.05161">pdf</a>, <a href="https://arxiv.org/ps/2212.05161">ps</a>, <a href="https://arxiv.org/format/2212.05161">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</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 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/PhysRevD.107.063518">10.1103/PhysRevD.107.063518 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Non-equilibrium dynamics of Axion-like particles: the quantum master equation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuyang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Boyanovsky%2C+D">Daniel Boyanovsky</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.05161v2-abstract-short" style="display: inline;"> We study the non-equilibrium dynamics of Axion-like particles (ALP) coupled to Standard Model degrees of freedom in thermal equilibrium. The Quantum Master Equation (QME) for the (ALP) reduced density matrix is derived to leading order in the coupling of the (ALP) to the thermal bath, but to \emph{all} orders of the bath couplings to degrees of freedom within or beyond the Standard Model other tha… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.05161v2-abstract-full').style.display = 'inline'; document.getElementById('2212.05161v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.05161v2-abstract-full" style="display: none;"> We study the non-equilibrium dynamics of Axion-like particles (ALP) coupled to Standard Model degrees of freedom in thermal equilibrium. The Quantum Master Equation (QME) for the (ALP) reduced density matrix is derived to leading order in the coupling of the (ALP) to the thermal bath, but to \emph{all} orders of the bath couplings to degrees of freedom within or beyond the Standard Model other than the (ALP). The (QME) describes the damped oscillation dynamics of an initial misaligned (ALP) condensate, thermalization with the bath, decoherence and entropy production within a unifying framework. The (ALP) energy density $\mathcal{E}(t)$ features two components: a ``cold'' component from the misaligned condensate and a ``hot'' component from thermalization with the bath, with $\mathcal{E}(t)= \mathcal{E}_{c}\,e^{-纬(T)\,t}+\mathcal{E}_{h}(1-e^{-纬(T)\,t})$ thus providing a ``mixed dark matter'' scenario. Relaxation of the (ALP) condensate, thermalization, decoherence and entropy production occur on similar time scales. An explicit example with (ALP)-photon coupling, valid post recombination yields a relaxation rate $纬(T)$ with a substantial enhancement from thermal emission and absorption. A misaligned condensate is decaying at least since recombination and on the same time scale thermalizing with the cosmic microwave background (CMB). Possible consequences for birefringence of the (CMB) and (ALP) contribution to the effective number of ultrarelativistic species and galaxy formation are discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.05161v2-abstract-full').style.display = 'none'; document.getElementById('2212.05161v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">28 pages</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. D 107, 063518 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.04857">arXiv:2210.04857</a> <span> [<a href="https://arxiv.org/pdf/2210.04857">pdf</a>, <a href="https://arxiv.org/format/2210.04857">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.133.120802">10.1103/PhysRevLett.133.120802 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Efficient characterization of qudit logical gates with gate set tomography using an error-free Virtual-Z-gate model </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Lall%2C+D">Deep Lall</a>, <a href="/search/quant-ph?searchtype=author&query=Bakr%2C+M">Mustafa Bakr</a>, <a href="/search/quant-ph?searchtype=author&query=Campanaro%2C+G">Giulio Campanaro</a>, <a href="/search/quant-ph?searchtype=author&query=Fasciati%2C+S">Simone Fasciati</a>, <a href="/search/quant-ph?searchtype=author&query=Wills%2C+J">James Wills</a>, <a href="/search/quant-ph?searchtype=author&query=Chidambaram%2C+V">Vivek Chidambaram</a>, <a href="/search/quant-ph?searchtype=author&query=Shteynas%2C+B">Boris Shteynas</a>, <a href="/search/quant-ph?searchtype=author&query=Rungger%2C+I">Ivan Rungger</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P">Peter Leek</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.04857v4-abstract-short" style="display: inline;"> Gate-set tomography (GST) characterizes the process matrix of quantum logic gates, along with measurement and state preparation errors in quantum processors. GST typically requires extensive data collection and significant computational resources for model estimation. We propose a more efficient GST approach for qudits, utilizing the qudit Hadamard and virtual Z gates to construct fiducials while… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.04857v4-abstract-full').style.display = 'inline'; document.getElementById('2210.04857v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.04857v4-abstract-full" style="display: none;"> Gate-set tomography (GST) characterizes the process matrix of quantum logic gates, along with measurement and state preparation errors in quantum processors. GST typically requires extensive data collection and significant computational resources for model estimation. We propose a more efficient GST approach for qudits, utilizing the qudit Hadamard and virtual Z gates to construct fiducials while assuming virtual Z gates are error-free. Our method reduces the computational costs of estimating characterization results, making GST more practical at scale. We experimentally demonstrate the applicability of this approach on a superconducting transmon qutrit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.04857v4-abstract-full').style.display = 'none'; document.getElementById('2210.04857v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.02776">arXiv:2210.02776</a> <span> [<a href="https://arxiv.org/pdf/2210.02776">pdf</a>, <a href="https://arxiv.org/ps/2210.02776">ps</a>, <a href="https://arxiv.org/format/2210.02776">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"> Satellite-based continuous-variable quantum key distribution under the Earth's gravitational field </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tonghua Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuo Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Sixuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+S">Shuai Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xiaobao Liu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.02776v1-abstract-short" style="display: inline;"> Long distance communication protocols cannot ignore the existence of the Earth's gravitational field and its effects on quantum states. In this work, we show a very general method to consider the effects of the Earth's gravitational field on continuous-variable quantum key distribution protocols. Our results show that the Earth's gravitational field erodes the ability of the two parties to perform… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.02776v1-abstract-full').style.display = 'inline'; document.getElementById('2210.02776v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.02776v1-abstract-full" style="display: none;"> Long distance communication protocols cannot ignore the existence of the Earth's gravitational field and its effects on quantum states. In this work, we show a very general method to consider the effects of the Earth's gravitational field on continuous-variable quantum key distribution protocols. Our results show that the Earth's gravitational field erodes the ability of the two parties to perform QKD in all the protocols. However, our findings also exhibit some interesting features, i.e., the key rates initially increase for a specific range of height parameter $h\simeq r_A/2$ and then gradually decrease with the increasing of the orbits of satellite $h$. A possible explanation is also provided in our analysis, considering the fact that gravitational frequency shift and special relativistic effects play different roles in the key rates. In addition, our findings show that the change in key rate effected by gravitational frequency shift can be determined at a level of $<1.0\%$ within the satellite height at geostationary Earth orbits. Our work could provide some interesting possibilities to reduce the loss key rate through the control of the orbital height of satellites. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.02776v1-abstract-full').style.display = 'none'; document.getElementById('2210.02776v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 3 figures, accepted for publication in Quantum Information Processing</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.07658">arXiv:2209.07658</a> <span> [<a href="https://arxiv.org/pdf/2209.07658">pdf</a>, <a href="https://arxiv.org/ps/2209.07658">ps</a>, <a href="https://arxiv.org/format/2209.07658">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</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 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/PhysRevD.106.123503">10.1103/PhysRevD.106.123503 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Brownian Axion-like particles </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuyang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Boyanovsky%2C+D">Daniel Boyanovsky</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="2209.07658v2-abstract-short" style="display: inline;"> We study the non-equilibrium dynamics of a pseudoscalar axion-like particle (ALP) weakly coupled to degrees of freedom in thermal equilibrium by obtaining its reduced density matrix. Its time evolution is determined by the in-in effective action which we obtain to leading order in the (ALP) coupling but to \emph{all orders} in the couplings of the bath to other fields within or beyond the standard… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.07658v2-abstract-full').style.display = 'inline'; document.getElementById('2209.07658v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.07658v2-abstract-full" style="display: none;"> We study the non-equilibrium dynamics of a pseudoscalar axion-like particle (ALP) weakly coupled to degrees of freedom in thermal equilibrium by obtaining its reduced density matrix. Its time evolution is determined by the in-in effective action which we obtain to leading order in the (ALP) coupling but to \emph{all orders} in the couplings of the bath to other fields within or beyond the standard model. The effective equation of motion for the (ALP) is a Langevin equation with noise and friction kernels obeying the fluctuation dissipation relation. A ``misaligned'' initial condition yields damped coherent oscillations, however, the (ALP) population increases towards thermalization with the bath. As a result, the energy density features a mixture of a cold component from misalignment and a hot component from thermalization with proportions that vary in time $(cold)\,e^{-螕t}+(hot)\,(1-e^{-螕t})$, providing a scenario wherein the ``warmth'' of the dark matter evolves in time from colder to hotter. As a specific example we consider the (ALP)-photon coupling $g a \vec{E}\cdot \vec{B}$ to lowest order, valid from recombination onwards. For $T \gg m_a$ the long-wavelength relaxation rate is substantially enhanced $螕_T = \frac{g^2\,m^2_a\,T}{16蟺} $. The ultraviolet divergences of the (ALP) self-energy require higher order derivative terms in the effective action. We find that at high temperature, the finite temperature effective mass of the (ALP) is $m^2_a(T) = m^2_a(0)\Big[ 1-(T/T_c)^4\Big]$, with $T_c \propto \sqrt{m_a(0)/g}$, \emph{suggesting} the possibility of an inverted phase transition, which when combined with higher derivatives may possibly indicate exotic new phases. We discuss possible cosmological consequences on structure formation, the effective number of relativistic species and birefringence of the cosmic microwave background. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.07658v2-abstract-full').style.display = 'none'; document.getElementById('2209.07658v2-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 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. D 106, 123503 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.13330">arXiv:2206.13330</a> <span> [<a href="https://arxiv.org/pdf/2206.13330">pdf</a>, <a href="https://arxiv.org/ps/2206.13330">ps</a>, <a href="https://arxiv.org/format/2206.13330">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="Cryptography and Security">cs.CR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1367-2630/acfab6">10.1088/1367-2630/acfab6 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multi-agent blind quantum computation without universal cluster states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2206.13330v3-abstract-short" style="display: inline;"> Blind quantum computation (BQC) protocols enable quantum algorithms to be executed on third-party quantum agents while keeping the data and algorithm confidential. The previous proposals for measurement-based BQC require preparing a highly entangled cluster state. In this paper, we show that such a requirement is not necessary. Our protocol only requires pre-shared bell pairs between delegated qua… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.13330v3-abstract-full').style.display = 'inline'; document.getElementById('2206.13330v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.13330v3-abstract-full" style="display: none;"> Blind quantum computation (BQC) protocols enable quantum algorithms to be executed on third-party quantum agents while keeping the data and algorithm confidential. The previous proposals for measurement-based BQC require preparing a highly entangled cluster state. In this paper, we show that such a requirement is not necessary. Our protocol only requires pre-shared bell pairs between delegated quantum agents, and there is no requirement for any classical or quantum information exchange between agents during the execution. Our proposal requires fewer quantum resources than previous proposals by eliminating the need for a universal cluster state. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.13330v3-abstract-full').style.display = 'none'; document.getElementById('2206.13330v3-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 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.06616">arXiv:2202.06616</a> <span> [<a href="https://arxiv.org/pdf/2202.06616">pdf</a>, <a href="https://arxiv.org/format/2202.06616">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0256-307X/39/3/030302">10.1088/0256-307X/39/3/030302 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Realization of fast all-microwave CZ gates with a tunable coupler </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+D">Daojin Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+M">Ming Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Y">Yangsen Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+X">Xiawei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yulin Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+H">Huijie Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+H">Hui Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Rong%2C+H">Hao Rong</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">He-Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zha%2C+C">Chen Zha</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+K">Kai Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shaojun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+H">Haoran Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+H">Haibin Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fusheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Q">Qingling Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Youwei Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Shiyu Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+C">Chong Ying</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Sirui Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+J">Jiale Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+F">Futian Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a> , et al. (7 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2202.06616v1-abstract-short" style="display: inline;"> The development of high-fidelity two-qubit quantum gates is essential for digital quantum computing. Here, we propose and realize an all-microwave parametric Controlled-Z (CZ) gates by coupling strength modulation in a superconducting Transmon qubit system with tunable couplers. After optimizing the design of the tunable coupler together with the control pulse numerically, we experimentally realiz… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.06616v1-abstract-full').style.display = 'inline'; document.getElementById('2202.06616v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.06616v1-abstract-full" style="display: none;"> The development of high-fidelity two-qubit quantum gates is essential for digital quantum computing. Here, we propose and realize an all-microwave parametric Controlled-Z (CZ) gates by coupling strength modulation in a superconducting Transmon qubit system with tunable couplers. After optimizing the design of the tunable coupler together with the control pulse numerically, we experimentally realized a 100 ns CZ gate with high fidelity of 99.38%$ \pm$0.34% and the control error being 0.1%. We note that our CZ gates are not affected by pulse distortion and do not need pulse correction, {providing a solution for the real-time pulse generation in a dynamic quantum feedback circuit}. With the expectation of utilizing our all-microwave control scheme to reduce the number of control lines through frequency multiplexing in the future, our scheme draws a blueprint for the high-integrable quantum hardware design. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.06616v1-abstract-full').style.display = 'none'; document.getElementById('2202.06616v1-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 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Chin. Phys. Lett.,39 (3): 030302 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.05957">arXiv:2201.05957</a> <span> [<a href="https://arxiv.org/pdf/2201.05957">pdf</a>, <a href="https://arxiv.org/format/2201.05957">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.scib.2023.04.003">10.1016/j.scib.2023.04.003 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum Neuronal Sensing of Quantum Many-Body States on a 61-Qubit Programmable Superconducting Processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gong%2C+M">Ming Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">He-Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Shiyu Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+C">Chu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yulin Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Q">Qingling Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Youwei Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shaojun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+H">Haoran Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Y">Yangsen Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Zha%2C+C">Chen Zha</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fusheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+C">Chong Ying</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+J">Jiale Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+D">Daojin Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+D">Dachao Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+H">Hong Su</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+H">Hui Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Rong%2C+H">Hao Rong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+K">Kaili Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Sirui Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Lihua Sun</a> , et al. (11 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2201.05957v2-abstract-short" style="display: inline;"> Classifying many-body quantum states with distinct properties and phases of matter is one of the most fundamental tasks in quantum many-body physics. However, due to the exponential complexity that emerges from the enormous numbers of interacting particles, classifying large-scale quantum states has been extremely challenging for classical approaches. Here, we propose a new approach called quantum… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.05957v2-abstract-full').style.display = 'inline'; document.getElementById('2201.05957v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.05957v2-abstract-full" style="display: none;"> Classifying many-body quantum states with distinct properties and phases of matter is one of the most fundamental tasks in quantum many-body physics. However, due to the exponential complexity that emerges from the enormous numbers of interacting particles, classifying large-scale quantum states has been extremely challenging for classical approaches. Here, we propose a new approach called quantum neuronal sensing. Utilizing a 61 qubit superconducting quantum processor, we show that our scheme can efficiently classify two different types of many-body phenomena: namely the ergodic and localized phases of matter. Our quantum neuronal sensing process allows us to extract the necessary information coming from the statistical characteristics of the eigenspectrum to distinguish these phases of matter by measuring only one qubit. Our work demonstrates the feasibility and scalability of quantum neuronal sensing for near-term quantum processors and opens new avenues for exploring quantum many-body phenomena in larger-scale systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.05957v2-abstract-full').style.display = 'none'; document.getElementById('2201.05957v2-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 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 3 figures in the main text, and 13 pages, 13 figures, and 1 table in supplementary materials</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science Bulletin, 68(9):906-912 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2112.13505">arXiv:2112.13505</a> <span> [<a href="https://arxiv.org/pdf/2112.13505">pdf</a>, <a href="https://arxiv.org/format/2112.13505">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.129.030501">10.1103/PhysRevLett.129.030501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Realization of an Error-Correcting Surface Code with Superconducting Qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Youwei Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Y">Yangsen Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">He-Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yiming Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+D">Dachao Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+H">Huijie Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Q">Qingling Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+Z">Zuolin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+T">Tan He</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Sirui Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fusheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chung%2C+T">Tung-Hsun Chung</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+H">Hui Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+D">Daojin Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+M">Ming Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+C">Cheng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shaojun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+L">Lianchen Han</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+N">Na Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+F">Futian Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+H">Haoran Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Rong%2C+H">Hao Rong</a> , et al. (14 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2112.13505v2-abstract-short" style="display: inline;"> Quantum error correction is a critical technique for transitioning from noisy intermediate-scale quantum (NISQ) devices to fully fledged quantum computers. The surface code, which has a high threshold error rate, is the leading quantum error correction code for two-dimensional grid architecture. So far, the repeated error correction capability of the surface code has not been realized experimental… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.13505v2-abstract-full').style.display = 'inline'; document.getElementById('2112.13505v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2112.13505v2-abstract-full" style="display: none;"> Quantum error correction is a critical technique for transitioning from noisy intermediate-scale quantum (NISQ) devices to fully fledged quantum computers. The surface code, which has a high threshold error rate, is the leading quantum error correction code for two-dimensional grid architecture. So far, the repeated error correction capability of the surface code has not been realized experimentally. Here, we experimentally implement an error-correcting surface code, the distance-3 surface code which consists of 17 qubits, on the \textit{Zuchongzhi} 2.1 superconducting quantum processor. By executing several consecutive error correction cycles, the logical error can be significantly reduced after applying corrections, achieving the repeated error correction of surface code for the first time. This experiment represents a fully functional instance of an error-correcting surface code, providing a key step on the path towards scalable fault-tolerant quantum computing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.13505v2-abstract-full').style.display = 'none'; document.getElementById('2112.13505v2-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 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 129, 030501 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.05176">arXiv:2111.05176</a> <span> [<a href="https://arxiv.org/pdf/2111.05176">pdf</a>, <a href="https://arxiv.org/format/2111.05176">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.physrep.2022.08.003">10.1016/j.physrep.2022.08.003 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Variational Quantum Eigensolver: a review of methods and best practices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tilly%2C+J">Jules Tilly</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Hongxiang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Picozzi%2C+D">Dario Picozzi</a>, <a href="/search/quant-ph?searchtype=author&query=Setia%2C+K">Kanav Setia</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Ying Li</a>, <a href="/search/quant-ph?searchtype=author&query=Grant%2C+E">Edward Grant</a>, <a href="/search/quant-ph?searchtype=author&query=Wossnig%2C+L">Leonard Wossnig</a>, <a href="/search/quant-ph?searchtype=author&query=Rungger%2C+I">Ivan Rungger</a>, <a href="/search/quant-ph?searchtype=author&query=Booth%2C+G+H">George H. Booth</a>, <a href="/search/quant-ph?searchtype=author&query=Tennyson%2C+J">Jonathan Tennyson</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2111.05176v3-abstract-short" style="display: inline;"> The variational quantum eigensolver (or VQE) uses the variational principle to compute the ground state energy of a Hamiltonian, a problem that is central to quantum chemistry and condensed matter physics. Conventional computing methods are constrained in their accuracy due to the computational limits. The VQE may be used to model complex wavefunctions in polynomial time, making it one of the most… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.05176v3-abstract-full').style.display = 'inline'; document.getElementById('2111.05176v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.05176v3-abstract-full" style="display: none;"> The variational quantum eigensolver (or VQE) uses the variational principle to compute the ground state energy of a Hamiltonian, a problem that is central to quantum chemistry and condensed matter physics. Conventional computing methods are constrained in their accuracy due to the computational limits. The VQE may be used to model complex wavefunctions in polynomial time, making it one of the most promising near-term applications for quantum computing. Finding a path to navigate the relevant literature has rapidly become an overwhelming task, with many methods promising to improve different parts of the algorithm. Despite strong theoretical underpinnings suggesting excellent scaling of individual VQE components, studies have pointed out that their various pre-factors could be too large to reach a quantum computing advantage over conventional methods. This review aims to provide an overview of the progress that has been made on the different parts of the algorithm. All the different components of the algorithm are reviewed in detail including representation of Hamiltonians and wavefunctions on a quantum computer, the optimization process, the post-processing mitigation of errors, and best practices are suggested. We identify four main areas of future research:(1) optimal measurement schemes for reduction of circuit repetitions; (2) large scale parallelization across many quantum computers;(3) ways to overcome the potential appearance of vanishing gradients in the optimization process, and how the number of iterations required for the optimization scales with system size; (4) the extent to which VQE suffers for quantum noise, and whether this noise can be mitigated. The answers to these open research questions will determine the routes for the VQE to achieve quantum advantage as the quantum computing hardware scales up and as the noise levels are reduced. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.05176v3-abstract-full').style.display = 'none'; document.getElementById('2111.05176v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">156 pages, 19 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.05680">arXiv:2109.05680</a> <span> [<a href="https://arxiv.org/pdf/2109.05680">pdf</a>, <a href="https://arxiv.org/format/2109.05680">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0256-307X/38/10/100301">10.1088/0256-307X/38/10/100301 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Realization of high-fidelity CZ gates in extensible superconducting qubits design with a tunable coupler </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Y">Yangsen Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Sirui Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yulin Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+X">Xiawei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Q">Qingling Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fusheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+M">Ming Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Zha%2C+C">Chen Zha</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">He-Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Youwei Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Shiyu Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shaojun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+H">Haoran Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+F">Futian Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+C">Cheng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Lihua Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+N">Na Li</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+H">Hui Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+X">Xiaobo Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2109.05680v1-abstract-short" style="display: inline;"> High-fidelity two-qubits gates are essential for the realization of large-scale quantum computation and simulation. Tunable coupler design is used to reduce the problem of parasitic coupling and frequency crowding in many-qubit systems and thus thought to be advantageous. Here we design a extensible 5-qubit system in which center transmon qubit can couple to every four near-neighbor qubit via a ca… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.05680v1-abstract-full').style.display = 'inline'; document.getElementById('2109.05680v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.05680v1-abstract-full" style="display: none;"> High-fidelity two-qubits gates are essential for the realization of large-scale quantum computation and simulation. Tunable coupler design is used to reduce the problem of parasitic coupling and frequency crowding in many-qubit systems and thus thought to be advantageous. Here we design a extensible 5-qubit system in which center transmon qubit can couple to every four near-neighbor qubit via a capacitive tunable coupler and experimentally demonstrate high-fidelity controlled-phase (CZ) gate by manipulating center qubit and one near-neighbor qubit. Speckle purity benchmarking (SPB) and cross entrophy benchmarking (XEB) are used to assess the purity fidelity and the fidelity of the CZ gate. The average purity fidelity of the CZ gate is 99.69$\pm$0.04\% and the average fidelity of the CZ gate is 99.65$\pm$0.04\% which means the control error is about 0.04\%. Our work will help resovle many chanllenges in the implementation of large scale quantum systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.05680v1-abstract-full').style.display = 'none'; document.getElementById('2109.05680v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> <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, 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/2109.03494">arXiv:2109.03494</a> <span> [<a href="https://arxiv.org/pdf/2109.03494">pdf</a>, <a href="https://arxiv.org/format/2109.03494">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 Computational Advantage via 60-Qubit 24-Cycle Random Circuit Sampling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Q">Qingling Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Sirui Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fusheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+M">Ming-Cheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+X">Xiawei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chung%2C+T">Tung-Hsun Chung</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+H">Hui Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+Y">Yajie Du</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+D">Daojin Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+M">Ming Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+C">Cheng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+C">Chu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shaojun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+L">Lianchen Han</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+L">Linyin Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">He-Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Huo%2C+Y">Yong-Heng Huo</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+L">Liping Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+N">Na Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+F">Futian Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+C">Chun Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+H">Haoran Qian</a> , et al. (28 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2109.03494v2-abstract-short" style="display: inline;"> To ensure a long-term quantum computational advantage, the quantum hardware should be upgraded to withstand the competition of continuously improved classical algorithms and hardwares. Here, we demonstrate a superconducting quantum computing systems \textit{Zuchongzhi} 2.1, which has 66 qubits in a two-dimensional array in a tunable coupler architecture. The readout fidelity of \textit{Zuchongzhi}… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.03494v2-abstract-full').style.display = 'inline'; document.getElementById('2109.03494v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.03494v2-abstract-full" style="display: none;"> To ensure a long-term quantum computational advantage, the quantum hardware should be upgraded to withstand the competition of continuously improved classical algorithms and hardwares. Here, we demonstrate a superconducting quantum computing systems \textit{Zuchongzhi} 2.1, which has 66 qubits in a two-dimensional array in a tunable coupler architecture. The readout fidelity of \textit{Zuchongzhi} 2.1 is considerably improved to an average of 97.74\%. The more powerful quantum processor enables us to achieve larger-scale random quantum circuit sampling, with a system scale of up to 60 qubits and 24 cycles. The achieved sampling task is about 6 orders of magnitude more difficult than that of Sycamore [Nature \textbf{574}, 505 (2019)] in the classic simulation, and 3 orders of magnitude more difficult than the sampling task on \textit{Zuchongzhi} 2.0 [arXiv:2106.14734 (2021)]. The time consumption of classically simulating random circuit sampling experiment using state-of-the-art classical algorithm and supercomputer is extended to tens of thousands of years (about $4.8\times 10^4$ years), while \textit{Zuchongzhi} 2.1 only takes about 4.2 hours, thereby significantly enhancing the quantum computational advantage. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.03494v2-abstract-full').style.display = 'none'; document.getElementById('2109.03494v2-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, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.02105">arXiv:2108.02105</a> <span> [<a href="https://arxiv.org/pdf/2108.02105">pdf</a>, <a href="https://arxiv.org/format/2108.02105">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.17.024058">10.1103/PhysRevApplied.17.024058 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterisation of spatial charge sensitivity in a multi-mode superconducting qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wills%2C+J">J. Wills</a>, <a href="/search/quant-ph?searchtype=author&query=Campanaro%2C+G">G. Campanaro</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">S. Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Fasciati%2C+S+D">S. D. Fasciati</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P+J">P. J. Leek</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">B. Vlastakis</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.02105v1-abstract-short" style="display: inline;"> Understanding and suppressing sources of decoherence is a leading challenge in building practical quantum computers. In superconducting qubits, low frequency charge noise is a well-known decoherence mechanism that is effectively suppressed in the transmon qubit. Devices with multiple charge-sensitive modes can exhibit more complex behaviours, which can be exploited to study charge fluctuations in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.02105v1-abstract-full').style.display = 'inline'; document.getElementById('2108.02105v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.02105v1-abstract-full" style="display: none;"> Understanding and suppressing sources of decoherence is a leading challenge in building practical quantum computers. In superconducting qubits, low frequency charge noise is a well-known decoherence mechanism that is effectively suppressed in the transmon qubit. Devices with multiple charge-sensitive modes can exhibit more complex behaviours, which can be exploited to study charge fluctuations in superconducting qubits. Here we characterise charge-sensitivity in a superconducting qubit with two transmon-like modes, each of which is sensitive to multiple charge-parity configurations and charge-offset biases. Using Ramsey interferometry, we observe sensitivity to four charge-parity configurations and track two independent charge-offset drifts over hour timescales. We provide a predictive theory for charge sensitivity in such multi-mode qubits which agrees with our results. Finally, we demonstrate the utility of a multi-mode qubit as a charge detector by spatially tracking local-charge drift. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.02105v1-abstract-full').style.display = 'none'; document.getElementById('2108.02105v1-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 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main: 6 pages, 4 figures. Appendices: 3 pages, 3 figures, 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 17, 024058 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.11140">arXiv:2107.11140</a> <span> [<a href="https://arxiv.org/pdf/2107.11140">pdf</a>, <a href="https://arxiv.org/format/2107.11140">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 Coherence in a Tileable 3D Integrated Superconducting Circuit Architecture </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Spring%2C+P+A">Peter A. Spring</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Tsunoda%2C+T">Takahiro Tsunoda</a>, <a href="/search/quant-ph?searchtype=author&query=Campanaro%2C+G">Giulio Campanaro</a>, <a href="/search/quant-ph?searchtype=author&query=Fasciati%2C+S+D">Simone D. Fasciati</a>, <a href="/search/quant-ph?searchtype=author&query=Wills%2C+J">James Wills</a>, <a href="/search/quant-ph?searchtype=author&query=Chidambaram%2C+V">Vivek Chidambaram</a>, <a href="/search/quant-ph?searchtype=author&query=Shteynas%2C+B">Boris Shteynas</a>, <a href="/search/quant-ph?searchtype=author&query=Bakr%2C+M">Mustafa Bakr</a>, <a href="/search/quant-ph?searchtype=author&query=Gow%2C+P">Paul Gow</a>, <a href="/search/quant-ph?searchtype=author&query=Carpenter%2C+L">Lewis Carpenter</a>, <a href="/search/quant-ph?searchtype=author&query=Gates%2C+J">James Gates</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P+J">Peter J. Leek</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.11140v1-abstract-short" style="display: inline;"> We report high qubit coherence as well as low crosstalk and single-qubit gate errors in a superconducting circuit architecture that promises to be tileable to 2D lattices of qubits. The architecture integrates an inductively shunted cavity enclosure into a design featuring non-galvanic out-of-plane control wiring and qubits and resonators fabricated on opposing sides of a substrate. The proof-of-p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.11140v1-abstract-full').style.display = 'inline'; document.getElementById('2107.11140v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.11140v1-abstract-full" style="display: none;"> We report high qubit coherence as well as low crosstalk and single-qubit gate errors in a superconducting circuit architecture that promises to be tileable to 2D lattices of qubits. The architecture integrates an inductively shunted cavity enclosure into a design featuring non-galvanic out-of-plane control wiring and qubits and resonators fabricated on opposing sides of a substrate. The proof-of-principle device features four uncoupled transmon qubits and exhibits average energy relaxation times $T_1=149(38)~渭$s, pure echoed dephasing times $T_{蠁,e}=189(34)~渭$s, and single-qubit gate fidelities $F=99.982(4)\%$ as measured by simultaneous randomized benchmarking. The 3D integrated nature of the control wiring means that qubits will remain addressable as the architecture is tiled to form larger qubit lattices. Band structure simulations are used to predict that the tiled enclosure will still provide a clean electromagnetic environment to enclosed qubits at arbitrary scale. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.11140v1-abstract-full').style.display = 'none'; document.getElementById('2107.11140v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main: 8 pages, 7 figures, 3 tables. Appendices: 8 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/2106.14734">arXiv:2106.14734</a> <span> [<a href="https://arxiv.org/pdf/2106.14734">pdf</a>, <a href="https://arxiv.org/format/2106.14734">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.127.180501">10.1103/PhysRevLett.127.180501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Strong quantum computational advantage using a superconducting quantum processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yulin Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Bao%2C+W">Wan-Su Bao</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Sirui Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fusheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+M">Ming-Cheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+X">Xiawei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chung%2C+T">Tung-Hsun Chung</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+H">Hui Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+Y">Yajie Du</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+D">Daojin Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+M">Ming Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+C">Cheng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+C">Chu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shaojun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+L">Lianchen Han</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+L">Linyin Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">He-Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Huo%2C+Y">Yong-Heng Huo</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+L">Liping Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+N">Na Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+F">Futian Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+C">Chun Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a> , et al. (29 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.14734v1-abstract-short" style="display: inline;"> Scaling up to a large number of qubits with high-precision control is essential in the demonstrations of quantum computational advantage to exponentially outpace the classical hardware and algorithmic improvements. Here, we develop a two-dimensional programmable superconducting quantum processor, \textit{Zuchongzhi}, which is composed of 66 functional qubits in a tunable coupling architecture. To… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.14734v1-abstract-full').style.display = 'inline'; document.getElementById('2106.14734v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.14734v1-abstract-full" style="display: none;"> Scaling up to a large number of qubits with high-precision control is essential in the demonstrations of quantum computational advantage to exponentially outpace the classical hardware and algorithmic improvements. Here, we develop a two-dimensional programmable superconducting quantum processor, \textit{Zuchongzhi}, which is composed of 66 functional qubits in a tunable coupling architecture. To characterize the performance of the whole system, we perform random quantum circuits sampling for benchmarking, up to a system size of 56 qubits and 20 cycles. The computational cost of the classical simulation of this task is estimated to be 2-3 orders of magnitude higher than the previous work on 53-qubit Sycamore processor [Nature \textbf{574}, 505 (2019)]. We estimate that the sampling task finished by \textit{Zuchongzhi} in about 1.2 hours will take the most powerful supercomputer at least 8 years. Our work establishes an unambiguous quantum computational advantage that is infeasible for classical computation in a reasonable amount of time. The high-precision and programmable quantum computing platform opens a new door to explore novel many-body phenomena and implement complex quantum algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.14734v1-abstract-full').style.display = 'none'; document.getElementById('2106.14734v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.02573">arXiv:2102.02573</a> <span> [<a href="https://arxiv.org/pdf/2102.02573">pdf</a>, <a href="https://arxiv.org/format/2102.02573">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.abg7812">10.1126/science.abg7812 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum walks on a programmable two-dimensional 62-qubit superconducting processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gong%2C+M">Ming Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Shiyu Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zha%2C+C">Chen Zha</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+M">Ming-Cheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">He-Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yulin Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Q">Qingling Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Youwei Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shaojun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+H">Haoran Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+Y">Yangsen Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fusheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+C">Chong Ying</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+J">Jiale Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+D">Daojin Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+D">Dachao Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+H">Hong Su</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+H">Hui Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Rong%2C+H">Hao Rong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+K">Kaili Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Sirui Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Lihua Sun</a> , et al. (11 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.02573v3-abstract-short" style="display: inline;"> Quantum walks are the quantum mechanical analogue of classical random walks and an extremely powerful tool in quantum simulations, quantum search algorithms, and even for universal quantum computing. In our work, we have designed and fabricated an 8x8 two-dimensional square superconducting qubit array composed of 62 functional qubits. We used this device to demonstrate high fidelity single and two… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.02573v3-abstract-full').style.display = 'inline'; document.getElementById('2102.02573v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.02573v3-abstract-full" style="display: none;"> Quantum walks are the quantum mechanical analogue of classical random walks and an extremely powerful tool in quantum simulations, quantum search algorithms, and even for universal quantum computing. In our work, we have designed and fabricated an 8x8 two-dimensional square superconducting qubit array composed of 62 functional qubits. We used this device to demonstrate high fidelity single and two particle quantum walks. Furthermore, with the high programmability of the quantum processor, we implemented a Mach-Zehnder interferometer where the quantum walker coherently traverses in two paths before interfering and exiting. By tuning the disorders on the evolution paths, we observed interference fringes with single and double walkers. Our work is an essential milestone in the field, brings future larger scale quantum applications closer to realization on these noisy intermediate-scale quantum processors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.02573v3-abstract-full').style.display = 'none'; document.getElementById('2102.02573v3-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 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 4 figures, and supplementary materials with 21 pages, 13 figures and 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science 372, 948-952 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.04047">arXiv:2009.04047</a> <span> [<a href="https://arxiv.org/pdf/2009.04047">pdf</a>, <a href="https://arxiv.org/ps/2009.04047">ps</a>, <a href="https://arxiv.org/format/2009.04047">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41598-020-71802-4">10.1038/s41598-020-71802-4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterization of quantum and classical correlations in the Earth curved space-time </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tonghua Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuo Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+S">Shumin Wu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2009.04047v1-abstract-short" style="display: inline;"> The preparation of quantum systems and the execution of quantum information tasks between distant users are always affected by gravitational and relativistic effects. In this work, we quantitatively analyze how the curved space-time background of the Earth affects the classical and quantum correlations between photon pairs that are initially prepared in a two-mode squeezed state. More specifically… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.04047v1-abstract-full').style.display = 'inline'; document.getElementById('2009.04047v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.04047v1-abstract-full" style="display: none;"> The preparation of quantum systems and the execution of quantum information tasks between distant users are always affected by gravitational and relativistic effects. In this work, we quantitatively analyze how the curved space-time background of the Earth affects the classical and quantum correlations between photon pairs that are initially prepared in a two-mode squeezed state. More specifically, considering the rotation of the Earth, the space-time around the Earth is described by the Kerr metric. Our results show that these state correlations, which initially increase for a specific range of satellite's orbital altitude, will gradually approach a finite value with increasing height of satellites orbit (when the special relativistic effects become relevant). More importantly, our analysis demonstrates that the changes of correlations generated by the total gravitational frequency shift could reach the level of <0.5$\%$ within the satellites height at geostationary Earth orbits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.04047v1-abstract-full').style.display = 'none'; document.getElementById('2009.04047v1-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 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 4 figures, accepted for publication in Scientific reports</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Scientific Reports, 10:14697 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.10721">arXiv:2008.10721</a> <span> [<a href="https://arxiv.org/pdf/2008.10721">pdf</a>, <a href="https://arxiv.org/format/2008.10721">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-021-23159-z">10.1038/s41467-021-23159-z <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ultrastrong Magnon-Magnon Coupling Dominated by Antiresonant Interactions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Makihara%2C+T">Takuma Makihara</a>, <a href="/search/quant-ph?searchtype=author&query=Hayashida%2C+K">Kenji Hayashida</a>, <a href="/search/quant-ph?searchtype=author&query=Noe%2C+G+T">G. Timothy Noe II</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xinwei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Peraca%2C+N+M">Nicolas Marquez Peraca</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiaoxuan Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+Z">Zuanming Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+W">Wei Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+G">Guohong Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Katayama%2C+I">Ikufumi Katayama</a>, <a href="/search/quant-ph?searchtype=author&query=Takeda%2C+J">Jun Takeda</a>, <a href="/search/quant-ph?searchtype=author&query=Nojiri%2C+H">Hiroyuki Nojiri</a>, <a href="/search/quant-ph?searchtype=author&query=Turchinovich%2C+D">Dmitry Turchinovich</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shixun Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Bamba%2C+M">Motoaki Bamba</a>, <a href="/search/quant-ph?searchtype=author&query=Kono%2C+J">Junichiro Kono</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.10721v2-abstract-short" style="display: inline;"> Exotic quantum vacuum phenomena are predicted in cavity quantum electrodynamics (QED) systems with ultrastrong light-matter interactions. Their ground states are predicted to be vacuum squeezed states with suppressed quantum fluctuations. The source of such phenomena are antiresonant terms in the Hamiltonian, yet antiresonant interactions are typically negligible compared to resonant interactions… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.10721v2-abstract-full').style.display = 'inline'; document.getElementById('2008.10721v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.10721v2-abstract-full" style="display: none;"> Exotic quantum vacuum phenomena are predicted in cavity quantum electrodynamics (QED) systems with ultrastrong light-matter interactions. Their ground states are predicted to be vacuum squeezed states with suppressed quantum fluctuations. The source of such phenomena are antiresonant terms in the Hamiltonian, yet antiresonant interactions are typically negligible compared to resonant interactions in light-matter systems. We report an unusual coupled matter-matter system of magnons that can simulate a unique cavity QED Hamiltonian with coupling strengths that are easily tunable into the ultrastrong coupling regime and with dominant antiresonant terms. We found a novel regime where vacuum Bloch-Siegert shifts, the hallmark of antiresonant interactions, greatly exceed analogous frequency shifts from resonant interactions. Further, we theoretically explored the system's ground state and calculated up to 5.9 dB of quantum fluctuation suppression. These observations demonstrate that magnonic systems provide an ideal platform for simulating exotic quantum vacuum phenomena predicted in ultrastrongly coupled light-matter systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.10721v2-abstract-full').style.display = 'none'; document.getElementById('2008.10721v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">36 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/2003.03783">arXiv:2003.03783</a> <span> [<a href="https://arxiv.org/pdf/2003.03783">pdf</a>, <a href="https://arxiv.org/ps/2003.03783">ps</a>, <a href="https://arxiv.org/format/2003.03783">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1674-1056/ab7d9a">10.1088/1674-1056/ab7d9a <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum fluctuation of entanglement for accelerated two-level detectors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Sixuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tonghua Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuo Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yuting Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Geng%2C+S">Shuaibo Geng</a>, <a href="/search/quant-ph?searchtype=author&query=Lian%2C+Y">Yujie Lian</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="2003.03783v1-abstract-short" style="display: inline;"> Quantum entanglement as the one of the most general quantum resources, can be quantified by von Neumann entropy. However, as we know, the von Neumann entropy is only statistical quantity or operator, it therefore has fluctuation. The quantum fluctuation of entanglement (QFE) between Unruh-Dewitt detector modeled by a two-level atom is investigated in a relativistic setting. The Unruh radiation and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.03783v1-abstract-full').style.display = 'inline'; document.getElementById('2003.03783v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2003.03783v1-abstract-full" style="display: none;"> Quantum entanglement as the one of the most general quantum resources, can be quantified by von Neumann entropy. However, as we know, the von Neumann entropy is only statistical quantity or operator, it therefore has fluctuation. The quantum fluctuation of entanglement (QFE) between Unruh-Dewitt detector modeled by a two-level atom is investigated in a relativistic setting. The Unruh radiation and quantum fluctuation effects affect the precise measurement of quantum entanglement. Inspired by this we present how the relativistic motion effects QFE for two entangled Unruh-Dewitt detectors when one of them is accelerated and interacts with the neighbor external scalar field. We find that QFE first increases by the Unruh thermal noise and then suddenly decays when the acceleration reaches at a considerably large value, which indicates that relativistic effect will lead to non-negligible QFE effect. We also find that the initial QFE (without acceleration effect) is minimum with the maximally entangled state. Moreover, although QFE has a huge decay when the acceleration is greater than $\sim0.96$, concurrence also decays to a very low value, the ratio $螖E/C$ therefore still large. According to the equivalence principle, our findings could be in principle applied to dynamics of QFE under the influence of gravitation field. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.03783v1-abstract-full').style.display = 'none'; document.getElementById('2003.03783v1-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 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">3 figures, 6 pages, accepted for publication in Chinese Physics B</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2003.02989">arXiv:2003.02989</a> <span> [<a href="https://arxiv.org/pdf/2003.02989">pdf</a>, <a href="https://arxiv.org/format/2003.02989">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</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"> TensorFlow Quantum: A Software Framework for Quantum Machine Learning </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Verdon%2C+G">Guillaume Verdon</a>, <a href="/search/quant-ph?searchtype=author&query=McCourt%2C+T">Trevor McCourt</a>, <a href="/search/quant-ph?searchtype=author&query=Martinez%2C+A+J">Antonio J. Martinez</a>, <a href="/search/quant-ph?searchtype=author&query=Yoo%2C+J+H">Jae Hyeon Yoo</a>, <a href="/search/quant-ph?searchtype=author&query=Isakov%2C+S+V">Sergei V. Isakov</a>, <a href="/search/quant-ph?searchtype=author&query=Massey%2C+P">Philip Massey</a>, <a href="/search/quant-ph?searchtype=author&query=Halavati%2C+R">Ramin Halavati</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+M+Y">Murphy Yuezhen Niu</a>, <a href="/search/quant-ph?searchtype=author&query=Zlokapa%2C+A">Alexander Zlokapa</a>, <a href="/search/quant-ph?searchtype=author&query=Peters%2C+E">Evan Peters</a>, <a href="/search/quant-ph?searchtype=author&query=Lockwood%2C+O">Owen Lockwood</a>, <a href="/search/quant-ph?searchtype=author&query=Skolik%2C+A">Andrea Skolik</a>, <a href="/search/quant-ph?searchtype=author&query=Jerbi%2C+S">Sofiene Jerbi</a>, <a href="/search/quant-ph?searchtype=author&query=Dunjko%2C+V">Vedran Dunjko</a>, <a href="/search/quant-ph?searchtype=author&query=Leib%2C+M">Martin Leib</a>, <a href="/search/quant-ph?searchtype=author&query=Streif%2C+M">Michael Streif</a>, <a href="/search/quant-ph?searchtype=author&query=Von+Dollen%2C+D">David Von Dollen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Hongxiang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Wiersema%2C+R">Roeland Wiersema</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">Hsin-Yuan Huang</a>, <a href="/search/quant-ph?searchtype=author&query=McClean%2C+J+R">Jarrod R. McClean</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Boixo%2C+S">Sergio Boixo</a> , et al. (4 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2003.02989v2-abstract-short" style="display: inline;"> We introduce TensorFlow Quantum (TFQ), an open source library for the rapid prototyping of hybrid quantum-classical models for classical or quantum data. This framework offers high-level abstractions for the design and training of both discriminative and generative quantum models under TensorFlow and supports high-performance quantum circuit simulators. We provide an overview of the software archi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.02989v2-abstract-full').style.display = 'inline'; document.getElementById('2003.02989v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2003.02989v2-abstract-full" style="display: none;"> We introduce TensorFlow Quantum (TFQ), an open source library for the rapid prototyping of hybrid quantum-classical models for classical or quantum data. This framework offers high-level abstractions for the design and training of both discriminative and generative quantum models under TensorFlow and supports high-performance quantum circuit simulators. We provide an overview of the software architecture and building blocks through several examples and review the theory of hybrid quantum-classical neural networks. We illustrate TFQ functionalities via several basic applications including supervised learning for quantum classification, quantum control, simulating noisy quantum circuits, and quantum approximate optimization. Moreover, we demonstrate how one can apply TFQ to tackle advanced quantum learning tasks including meta-learning, layerwise learning, Hamiltonian learning, sampling thermal states, variational quantum eigensolvers, classification of quantum phase transitions, generative adversarial networks, and reinforcement learning. We hope this framework provides the necessary tools for the quantum computing and machine learning research communities to explore models of both natural and artificial quantum systems, and ultimately discover new quantum algorithms which could potentially yield a quantum advantage. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.02989v2-abstract-full').style.display = 'none'; document.getElementById('2003.02989v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">56 pages, 34 figures, many updates throughout the manuscript, several new sections are added</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1910.03902">arXiv:1910.03902</a> <span> [<a href="https://arxiv.org/pdf/1910.03902">pdf</a>, <a href="https://arxiv.org/format/1910.03902">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.101.052309">10.1103/PhysRevA.101.052309 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cost function embedding and dataset encoding for machine learning with parameterized quantum circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Wossnig%2C+L">Leonard Wossnig</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P">Peter Leek</a>, <a href="/search/quant-ph?searchtype=author&query=Grant%2C+E">Edward Grant</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1910.03902v1-abstract-short" style="display: inline;"> Machine learning is seen as a promising application of quantum computation. For near-term noisy intermediate-scale quantum (NISQ) devices, parametrized quantum circuits (PQCs) have been proposed as machine learning models due to their robustness and ease of implementation. However, the cost function is normally calculated classically from repeated measurement outcomes, such that it is no longer en… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.03902v1-abstract-full').style.display = 'inline'; document.getElementById('1910.03902v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.03902v1-abstract-full" style="display: none;"> Machine learning is seen as a promising application of quantum computation. For near-term noisy intermediate-scale quantum (NISQ) devices, parametrized quantum circuits (PQCs) have been proposed as machine learning models due to their robustness and ease of implementation. However, the cost function is normally calculated classically from repeated measurement outcomes, such that it is no longer encoded in a quantum state. This prevents the value from being directly manipulated by a quantum computer. To solve this problem, we give a routine to embed the cost function for machine learning into a quantum circuit, which accepts a training dataset encoded in superposition or an easily preparable mixed state. We also demonstrate the ability to evaluate the gradient of the encoded cost function in a quantum state. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.03902v1-abstract-full').style.display = 'none'; document.getElementById('1910.03902v1-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, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 101, 052309 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1910.02595">arXiv:1910.02595</a> <span> [<a href="https://arxiv.org/pdf/1910.02595">pdf</a>, <a href="https://arxiv.org/ps/1910.02595">ps</a>, <a href="https://arxiv.org/format/1910.02595">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1612-202X/ab2be4">10.1088/1612-202X/ab2be4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The influence of the Earth's curved spacetime on Gaussian quantum coherence </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tonghua Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+S">Shumin Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuo Cao</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1910.02595v1-abstract-short" style="display: inline;"> Light wave-packets propagating from the Earth to satellites will be deformed by the curved background spacetime of the Earth, thus influencing the quantum state of light. We show that Gaussian coherence of photon pairs, which are initially prepared in a two-mode squeezed state, is affected by the curved spacetime background of the Earth. We demonstrate that quantum coherence of the state increases… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.02595v1-abstract-full').style.display = 'inline'; document.getElementById('1910.02595v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.02595v1-abstract-full" style="display: none;"> Light wave-packets propagating from the Earth to satellites will be deformed by the curved background spacetime of the Earth, thus influencing the quantum state of light. We show that Gaussian coherence of photon pairs, which are initially prepared in a two-mode squeezed state, is affected by the curved spacetime background of the Earth. We demonstrate that quantum coherence of the state increases for a specific range of height h and then gradually approaches a finite value with further increasing height of the satellite's orbit in Kerr spacetime, because special relativistic effect are involved. Meanwhile, we find that Gaussian coherence increases with the increase of Gaussian bandwidth parameter, but the Gaussian coherence decreases with the growth of the peak frequency. In addition, we also find that total gravitational frequency shift causes changes of Gaussian coherence less than $%1$ and different initial peak frequencies also can effect rate of change with the satellite height in geostationary Earth orbits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.02595v1-abstract-full').style.display = 'none'; document.getElementById('1910.02595v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">arXiv admin note: substantial text overlap with arXiv:1808.09100</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> Laser Physics Letters, Volume 16, Issue 9 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Laser Physics Letters (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1804.03680">arXiv:1804.03680</a> <span> [<a href="https://arxiv.org/pdf/1804.03680">pdf</a>, <a href="https://arxiv.org/format/1804.03680">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-018-0116-9">10.1038/s41534-018-0116-9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Hierarchical quantum classifiers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Grant%2C+E">Edward Grant</a>, <a href="/search/quant-ph?searchtype=author&query=Benedetti%2C+M">Marcello Benedetti</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Hallam%2C+A">Andrew Hallam</a>, <a href="/search/quant-ph?searchtype=author&query=Lockhart%2C+J">Joshua Lockhart</a>, <a href="/search/quant-ph?searchtype=author&query=Stojevic%2C+V">Vid Stojevic</a>, <a href="/search/quant-ph?searchtype=author&query=Green%2C+A+G">Andrew G. Green</a>, <a href="/search/quant-ph?searchtype=author&query=Severini%2C+S">Simone Severini</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="1804.03680v2-abstract-short" style="display: inline;"> Quantum circuits with hierarchical structure have been used to perform binary classification of classical data encoded in a quantum state. We demonstrate that more expressive circuits in the same family achieve better accuracy and can be used to classify highly entangled quantum states, for which there is no known efficient classical method. We compare performance for several different parameteriz… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1804.03680v2-abstract-full').style.display = 'inline'; document.getElementById('1804.03680v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1804.03680v2-abstract-full" style="display: none;"> Quantum circuits with hierarchical structure have been used to perform binary classification of classical data encoded in a quantum state. We demonstrate that more expressive circuits in the same family achieve better accuracy and can be used to classify highly entangled quantum states, for which there is no known efficient classical method. We compare performance for several different parameterizations on two classical machine learning datasets, Iris and MNIST, and on a synthetic dataset of quantum states. Finally, we demonstrate that performance is robust to noise and deploy an Iris dataset classifier on the ibmqx4 quantum computer. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1804.03680v2-abstract-full').style.display = 'none'; document.getElementById('1804.03680v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 December, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 April, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 4, 65 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1611.09622">arXiv:1611.09622</a> <span> [<a href="https://arxiv.org/pdf/1611.09622">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div 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.94.063621">10.1103/PhysRevA.94.063621 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Modal decomposition of a propagating matter wave via electron ptychography </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">S. Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Kok%2C+P">P. Kok</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+P">P. Li</a>, <a href="/search/quant-ph?searchtype=author&query=Maiden%2C+A+M">A. M. Maiden</a>, <a href="/search/quant-ph?searchtype=author&query=Rodenburg%2C+J+M">J. M. Rodenburg</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="1611.09622v1-abstract-short" style="display: inline;"> We employ ptychography, a phase-retrieval imaging technique, to show experimentally for the first time that a partially coherent high-energy matter (electron) wave emanating from an extended source can be decomposed into a set of mutually independent modes of minimal rank. Partial coherence significantly determines the optical transfer properties of an electron microscope and so there has been muc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.09622v1-abstract-full').style.display = 'inline'; document.getElementById('1611.09622v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1611.09622v1-abstract-full" style="display: none;"> We employ ptychography, a phase-retrieval imaging technique, to show experimentally for the first time that a partially coherent high-energy matter (electron) wave emanating from an extended source can be decomposed into a set of mutually independent modes of minimal rank. Partial coherence significantly determines the optical transfer properties of an electron microscope and so there has been much work on this subject. However, previous studies have employed forms of interferometry to determine spatial coherence between discrete points in the wavefield. Here we use the density matrix to derive a formal quantum mechanical description of electron ptychography and use it to measure a full description of the spatial coherence of a propagating matter wavefield, at least to the within the fundamental uncertainties of the measurements we can obtain. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.09622v1-abstract-full').style.display = 'none'; document.getElementById('1611.09622v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 November, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2016. </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, 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/1611.01814">arXiv:1611.01814</a> <span> [<a href="https://arxiv.org/pdf/1611.01814">pdf</a>, <a href="https://arxiv.org/format/1611.01814">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="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Terahertz-frequency magnon-phonon-polaritons in the strong coupling regime </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sivarajah%2C+P">Prasahnt Sivarajah</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+J">Jian Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Xiang%2C+M">Maolin Xiang</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+W">Wei Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Kamba%2C+S">Stanislav Kamba</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shixun Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Nelson%2C+K+A">Keith A. Nelson</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="1611.01814v3-abstract-short" style="display: inline;"> Strong coupling between light and matter occurs when the two interact strongly enough to form new hybrid modes called polaritons. Here we report on the strong coupling of both the electric and magnetic degrees of freedom to an ultrafast terahertz (THz) frequency electromagnetic wave. In our system, optical phonons in a slab of ferroelectric lithium niobate (LiNbO$_3$) are strongly coupled to a THz… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.01814v3-abstract-full').style.display = 'inline'; document.getElementById('1611.01814v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1611.01814v3-abstract-full" style="display: none;"> Strong coupling between light and matter occurs when the two interact strongly enough to form new hybrid modes called polaritons. Here we report on the strong coupling of both the electric and magnetic degrees of freedom to an ultrafast terahertz (THz) frequency electromagnetic wave. In our system, optical phonons in a slab of ferroelectric lithium niobate (LiNbO$_3$) are strongly coupled to a THz electric field to form phonon-polaritons, which are simultaneously strongly coupled to magnons in an adjacent slab of canted antiferromagnetic erbium orthoferrite (ErFeO$_3$) via the THz magnetic field. The strong coupling leads to the formation of new magnon-phonon-polariton modes, which we experimentally observe in the wavevector-frequency dispersion curve as an avoided crossing and in the time-domain as a normal-mode beating. Our simple yet versatile on-chip waveguide platform provides a promising avenue by which to explore both ultrafast THz spintronics applications and the quantum nature of the interaction. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.01814v3-abstract-full').style.display = 'none'; document.getElementById('1611.01814v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 November, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2016. </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, Appendix A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1512.02031">arXiv:1512.02031</a> <span> [<a href="https://arxiv.org/pdf/1512.02031">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s12274-015-0910-z">10.1007/s12274-015-0910-z <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of coupling between zero- and two-dimensional semiconductor systems based on anomalous diamagnetic effects </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuo Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+J">Jing Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+Y">Yue Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+K">Kai Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+Y">Yunan Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Yanhui Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+C">Chenjiang Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+S">Sibai Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Ali%2C+H">Hassan Ali</a>, <a href="/search/quant-ph?searchtype=author&query=Shao%2C+Y">Yuting Shao</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+S">Shiyao Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+F">Feilong Song</a>, <a href="/search/quant-ph?searchtype=author&query=Williams%2C+D+A">David A. Williams</a>, <a href="/search/quant-ph?searchtype=author&query=Sheng%2C+W">Weidong Sheng</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+K">Kuijuan Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+X">Xiulai Xu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1512.02031v1-abstract-short" style="display: inline;"> We report the direct observation of coupling between a single self-assembled InAs quantum dot and a wetting layer, based on strong diamagnetic shifts of many-body exciton states using magneto-photoluminescence spectroscopy. An extremely large positive diamagnetic coefficient is observed when an electron in the wetting layer combines with a hole in the quantum dot; the coefficient is nearly one ord… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.02031v1-abstract-full').style.display = 'inline'; document.getElementById('1512.02031v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1512.02031v1-abstract-full" style="display: none;"> We report the direct observation of coupling between a single self-assembled InAs quantum dot and a wetting layer, based on strong diamagnetic shifts of many-body exciton states using magneto-photoluminescence spectroscopy. An extremely large positive diamagnetic coefficient is observed when an electron in the wetting layer combines with a hole in the quantum dot; the coefficient is nearly one order of magnitude larger than that of the exciton states confined in the quantum dots. Recombination of electrons with holes in a quantum dot of the coupled system leads to an unusual negative diamagnetic effect, which is five times stronger than that in a pure quantum dot system. This effect can be attributed to the expansion of the wavefunction of remaining electrons in the wetting layer or the spread of electrons in the excited states of the quantum dot to the wetting layer after recombination. In this case, the wavefunction extent of the final states in the quantum dot plane is much larger than that of the initial states because of the absence of holes in the quantum dot to attract electrons. The properties of emitted photons that depend on the large electron wavefunction extents in the wetting layer indicate that the coupling occurs between systems of different dimensionality, which is also verified from the results obtained by applying a magnetic field in different configurations. This study paves a new way to observe hybrid states with zero- and two-dimensional structures, which could be useful for investigating the Kondo physics and implementing spin-based solid-state quantum information processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.02031v1-abstract-full').style.display = 'none'; document.getElementById('1512.02031v1-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 December, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 7 figures in Nano Research, 2015</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1501.07853">arXiv:1501.07853</a> <span> [<a href="https://arxiv.org/pdf/1501.07853">pdf</a>, <a href="https://arxiv.org/ps/1501.07853">ps</a>, <a href="https://arxiv.org/format/1501.07853">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/srep08041">10.1038/srep08041 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Longitudinal wave function control in single quantum dots with an applied magnetic field </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuo Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+J">Jing Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+Y">Yunan Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+Y">Yue Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+K">Kangsheng Qiu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Yanhui Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+M">Min He</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+J">Jin-An Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Gu%2C+L">Lin Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Williams%2C+D+A">David A. Williams</a>, <a href="/search/quant-ph?searchtype=author&query=Sheng%2C+W">Weidong Sheng</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+K">Kuijuan Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+X">Xiulai Xu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1501.07853v1-abstract-short" style="display: inline;"> Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1501.07853v1-abstract-full').style.display = 'inline'; document.getElementById('1501.07853v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1501.07853v1-abstract-full" style="display: none;"> Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1501.07853v1-abstract-full').style.display = 'none'; document.getElementById('1501.07853v1-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 January, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages,3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Scientific Reports, 5, 8041 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1412.0800">arXiv:1412.0800</a> <span> [<a href="https://arxiv.org/pdf/1412.0800">pdf</a>, <a href="https://arxiv.org/ps/1412.0800">ps</a>, <a href="https://arxiv.org/format/1412.0800">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1364/JOSAB.32.000201">10.1364/JOSAB.32.000201 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dynamical generation of dark solitons in spin-orbit-coupled Bose-Einstein condensates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuai Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Shan%2C+C">Chuan-Jia Shan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+D">Dan-Wei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+X">Xizhou Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+J">Jun Xu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1412.0800v2-abstract-short" style="display: inline;"> We numerically investigate the ground state, the Raman-driving dynamics and the nonlinear excitations of a realized spin-orbit-coupled Bose-Einstein condensate in a one-dimensional harmonic trap. Depending on the Raman coupling and the interatomic interactions, three ground-state phases are identified: stripe, plane wave and zero-momentum phases. A narrow parameter regime with coexistence of strip… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1412.0800v2-abstract-full').style.display = 'inline'; document.getElementById('1412.0800v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1412.0800v2-abstract-full" style="display: none;"> We numerically investigate the ground state, the Raman-driving dynamics and the nonlinear excitations of a realized spin-orbit-coupled Bose-Einstein condensate in a one-dimensional harmonic trap. Depending on the Raman coupling and the interatomic interactions, three ground-state phases are identified: stripe, plane wave and zero-momentum phases. A narrow parameter regime with coexistence of stripe and zero-momentum or plane wave phases in real space is found. Several sweep progresses across different phases by driving the Raman coupling linearly in time is simulated and the non-equilibrium dynamics of the system in these sweeps are studied. We find kinds of nonlinear excitations, with the particular dark solitons excited in the sweep from the stripe phase to the plane wave or zero-momentum phase within the trap. Moreover, the number and the stability of the dark solitons can be controlled in the driving, which provide a direct and easy way to generate dark solitons and study their dynamics and interaction properties. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1412.0800v2-abstract-full').style.display = 'none'; document.getElementById('1412.0800v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 January, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 December, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2014. </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, 9 figure</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Opt. Soc. Am. B 32, 201 (2015) </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> </main> <footer> <div class="columns is-desktop" role="navigation" aria-label="Secondary">  <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/about">About</a></li> <li><a href="https://info.arxiv.org/help">Help</a></li> </ul> </div> <div class="column"> <ul class="nav-spaced"> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>contact arXiv</title><desc>Click here to contact arXiv</desc><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg> <a href="https://info.arxiv.org/help/contact.html"> Contact</a> </li> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>subscribe to arXiv mailings</title><desc>Click here to subscribe</desc><path d="M476 3.2L12.5 270.6c-18.1 10.4-15.8 35.6 2.2 43.2L121 358.4l287.3-253.2c5.5-4.9 13.3 2.6 8.6 8.3L176 407v80.5c0 23.6 28.5 32.9 42.5 15.8L282 426l124.6 52.2c14.2 6 30.4-2.9 33-18.2l72-432C515 7.8 493.3-6.8 476 3.2z"/></svg> <a href="https://info.arxiv.org/help/subscribe"> Subscribe</a> </li> </ul> </div> </div> </div>   <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/license/index.html">Copyright</a></li> <li><a href="https://info.arxiv.org/help/policies/privacy_policy.html">Privacy Policy</a></li> </ul> </div> <div class="column sorry-app-links"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/web_accessibility.html">Web Accessibility Assistance</a></li> <li> <p class="help"> <a class="a11y-main-link" href="https://status.arxiv.org" target="_blank">arXiv Operational Status <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 512" class="icon filter-dark_grey" role="presentation"><path d="M224.3 273l-136 136c-9.4 9.4-24.6 9.4-33.9 0l-22.6-22.6c-9.4-9.4-9.4-24.6 0-33.9l96.4-96.4-96.4-96.4c-9.4-9.4-9.4-24.6 0-33.9L54.3 103c9.4-9.4 24.6-9.4 33.9 0l136 136c9.5 9.4 9.5 24.6.1 34z"/></svg></a><br> Get status notifications via <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/email/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg>email</a> or <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/slack/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512" class="icon filter-black" role="presentation"><path d="M94.12 315.1c0 25.9-21.16 47.06-47.06 47.06S0 341 0 315.1c0-25.9 21.16-47.06 47.06-47.06h47.06v47.06zm23.72 0c0-25.9 21.16-47.06 47.06-47.06s47.06 21.16 47.06 47.06v117.84c0 25.9-21.16 47.06-47.06 47.06s-47.06-21.16-47.06-47.06V315.1zm47.06-188.98c-25.9 0-47.06-21.16-47.06-47.06S139 32 164.9 32s47.06 21.16 47.06 47.06v47.06H164.9zm0 23.72c25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06H47.06C21.16 243.96 0 222.8 0 196.9s21.16-47.06 47.06-47.06H164.9zm188.98 47.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06h-47.06V196.9zm-23.72 0c0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06V79.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06V196.9zM283.1 385.88c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06v-47.06h47.06zm0-23.72c-25.9 0-47.06-21.16-47.06-47.06 0-25.9 21.16-47.06 47.06-47.06h117.84c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06H283.1z"/></svg>slack</a> </p> </li> </ul> </div> </div> </div>  </div> </footer> <script src="https://static.arxiv.org/static/base/1.0.0a5/js/member_acknowledgement.js"></script> </body> </html>

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