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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="Pan, X"> <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> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Pan%2C+X&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Pan%2C+X&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Pan%2C+X&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.18880">arXiv:2502.18880</a> <span> [<a href="https://arxiv.org/pdf/2502.18880">pdf</a>, <a href="https://arxiv.org/format/2502.18880">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"> Universal quantum homomorphic encryption based on $(k, n)$-threshold quantum state sharing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+H">Haoyun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Lei%2C+Y">Yu-Ting Lei</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xing-bo 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="2502.18880v1-abstract-short" style="display: inline;"> Quantum homomorphic encryption integrates quantum computing with homomorphic encryption, which allows calculations to be performed directly on encrypted data without decryption on the server side. In this paper, we explore distributed quantum homomorphic encryption, focusing on the coordination of multiple evaluators to achieve evaluation tasks, which not only ensures security but also boosts comp… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.18880v1-abstract-full').style.display = 'inline'; document.getElementById('2502.18880v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.18880v1-abstract-full" style="display: none;"> Quantum homomorphic encryption integrates quantum computing with homomorphic encryption, which allows calculations to be performed directly on encrypted data without decryption on the server side. In this paper, we explore distributed quantum homomorphic encryption, focusing on the coordination of multiple evaluators to achieve evaluation tasks, which not only ensures security but also boosts computational power. Notably, we propose a $(k, n)$-threshold universal quantum homomorphic encryption scheme based on quantum state sharing. Each server is capable of executing a universal gate set, including the Clifford gates $\{X,Y,Z,H,S,CNOT\}$ and a non-Clifford T gate. The scheme provides that k evaluation servers chosen from $n$ $(0 < k \leq n)$ cooperate to complete the quantum homomorphic encryption so that the client can get the evaluated plaintext after decryption. Several concrete examples are presented to provide clarity to our solution. We also include security analysis, demonstrating its security against eavesdroppers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.18880v1-abstract-full').style.display = 'none'; document.getElementById('2502.18880v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.06775">arXiv:2411.06775</a> <span> [<a href="https://arxiv.org/pdf/2411.06775">pdf</a>, <a href="https://arxiv.org/format/2411.06775">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"> Nonreciprocal interaction and entanglement between two superconducting qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ren%2C+Y">Yu-Meng Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xue-Feng Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+X">Xiao-Yu Yao</a>, <a href="/search/quant-ph?searchtype=author&query=Huo%2C+X">Xiao-Wen Huo</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+J">Jun-Cong Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Hei%2C+X">Xin-Lei Hei</a>, <a href="/search/quant-ph?searchtype=author&query=Qiao%2C+Y">Yi-Fan Qiao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+P">Peng-Bo Li</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.06775v1-abstract-short" style="display: inline;"> Nonreciprocal interaction between two spatially separated subsystems plays a crucial role in signal processing and quantum networks. Here, we propose an efficient scheme to achieve nonreciprocal interaction and entanglement between two qubits by combining coherent and dissipative couplings in a superconducting platform, where two coherently coupled transmon qubits simultaneously interact with a tr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06775v1-abstract-full').style.display = 'inline'; document.getElementById('2411.06775v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.06775v1-abstract-full" style="display: none;"> Nonreciprocal interaction between two spatially separated subsystems plays a crucial role in signal processing and quantum networks. Here, we propose an efficient scheme to achieve nonreciprocal interaction and entanglement between two qubits by combining coherent and dissipative couplings in a superconducting platform, where two coherently coupled transmon qubits simultaneously interact with a transmission line waveguide. The coherent interaction between the transmon qubits can be achieved via capacitive coupling or via an intermediary cavity mode, while the dissipative interaction is induced by the transmission line via reservoir engineering. With high tunability of superconducting qubits, their positions along the transmission line can be adjusted to tune the dissipative coupling, enabling to tailor reciprocal and nonreciprocal interactions between the qubits. A fully nonreciprocal interaction can be achieved when the separation between the two qubits is $(4n+3)位_{0} /4$, where $n$ is an integer and $位_{0}$ is the photon wavelength. This nonreciprocal interaction enables the generation of nonreciprocal entanglement between the two transmon qubits. Furthermore, applying a drive field to one of the qubit can stabilize the system into a nonreciprocal steady-state entangled state. Remarkably, the nonreciprocal interaction in this work does not rely on the presence of nonlinearity or complex configurations, which has more potential applications in designing nonreciprocal quantum devices, processing quantum information, and building quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06775v1-abstract-full').style.display = 'none'; document.getElementById('2411.06775v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.10275">arXiv:2410.10275</a> <span> [<a href="https://arxiv.org/pdf/2410.10275">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Probing the Meissner effect in pressurized bilayer nickelate superconductors using diamond quantum sensors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wen%2C+J">Junyan Wen</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yue Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+G">Gang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Z">Ze-Xu He</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+N">Ningning Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+T">Tenglong Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiaoli Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+F">Feng Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liucheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+M">Miao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+J">Jing-Wei Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xiaobing Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+J">Jinguang Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+X">Xiaohui Yu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.10275v1-abstract-short" style="display: inline;"> Recent reports on the signatures of high-temperature superconductivity with a critical temperature Tc close to 80 K have triggered great research interest and extensive follow-up studies. Although zero-resistance state has been successfully achieved under improved hydrostatic pressure conditions, there is no clear evidence of superconducting diamagnetism in pressurized… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.10275v1-abstract-full').style.display = 'inline'; document.getElementById('2410.10275v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.10275v1-abstract-full" style="display: none;"> Recent reports on the signatures of high-temperature superconductivity with a critical temperature Tc close to 80 K have triggered great research interest and extensive follow-up studies. Although zero-resistance state has been successfully achieved under improved hydrostatic pressure conditions, there is no clear evidence of superconducting diamagnetism in pressurized $\mathrm{La_{3}Ni_{2}O_{7-未}}$ due to the low superconducting volume fraction and limited magnetic measurement techniques under high pressure conditions. Here, using shallow nitrogen-vacancy centers implanted on the culet of diamond anvils as in-situ quantum sensors, we observe convincing evidence for the Meissner effect in polycrystalline samples $\mathrm{La_{3}Ni_{2}O_{7-未}}$ and $\mathrm{La_{2}PrNi_{2}O_{7}}$: the magnetic field expulsion during both field cooling and field warming processes. The correlated measurements of Raman spectra and NV-based magnetic imaging indicate an incomplete structural transformation related to the displacement of oxygen ions emerging in the non-superconducting region. Furthermore, comparative experiments on different pressure transmitting media (silicone oil and KBr) and nickelates ($\mathrm{La_{3}Ni_{2}O_{7-未}}$ and $\mathrm{La_{2}PrNi_{2}O_{7}}$) reveal that an improved hydrostatic pressure conditions and the substitution of La by Pr in $\mathrm{La_{3}Ni_{2}O_{7-未}}$ can dramatically increase the superconductivity. Our work clarifies the controversy about the Meissner effect of bilayer nickelate and contributes to a deeper understanding of the mechanism of nickelate high-temperature superconductors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.10275v1-abstract-full').style.display = 'none'; document.getElementById('2410.10275v1-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/2410.06838">arXiv:2410.06838</a> <span> [<a href="https://arxiv.org/pdf/2410.06838">pdf</a>, <a href="https://arxiv.org/format/2410.06838">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> $蠁_0$-junction and Josephson diode effect in high-temperature superconductor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guo-Liang Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiao-Hong Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xin 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="2410.06838v1-abstract-short" style="display: inline;"> Motivated by recent progress in both the Josephson diode effect (JDE) and the high-temperature Josephson junction, we propose to realize the JDE in an s-wave/d-wave/s-wave (s-d-s) superconductor junction and investigate the high-temperature superconducting order parameters. The interlayer coupling between s-wave and d-wave superconductors can induce an effective $d+is$ superconducting state, spont… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.06838v1-abstract-full').style.display = 'inline'; document.getElementById('2410.06838v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.06838v1-abstract-full" style="display: none;"> Motivated by recent progress in both the Josephson diode effect (JDE) and the high-temperature Josephson junction, we propose to realize the JDE in an s-wave/d-wave/s-wave (s-d-s) superconductor junction and investigate the high-temperature superconducting order parameters. The interlayer coupling between s-wave and d-wave superconductors can induce an effective $d+is$ superconducting state, spontaneously breaking time-reversal symmetry. The asymmetric s-d interlayer couplings break the inversion symmetry. Remarkably, the breaking of these two symmetries leads to a $蠁_0$-junction but does not generate JDE. We find that the emergence of the JDE in this junction depends on the $C_4$ rotational symmetry of the system. Although breaking $C_4$ rotational symmetry does not affect time-reversal and inversion symmetries, it can control the magnitude and polarity of diode efficiency. Furthermore, we propose observing C$_{4}$ symmetry breaking controlled JDE through asymmetric Shapiro steps. Our work suggests a JDE mechanism that relies on high-temperature d-wave pairing, which could inversely contribute to a potential experimental method for detecting the unconventional pairing symmetry in superconductors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.06838v1-abstract-full').style.display = 'none'; document.getElementById('2410.06838v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.03084">arXiv:2410.03084</a> <span> [<a href="https://arxiv.org/pdf/2410.03084">pdf</a>, <a href="https://arxiv.org/format/2410.03084">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"> Dissipation-accelerated entanglement generation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+X">Xiao-Wei Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+J">Jun-Cong Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xue-Feng Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+L">Li-Hua Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+P">Pei-Rong Han</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+P">Peng-Bo Li</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.03084v1-abstract-short" style="display: inline;"> Dissipation is usually considered a negative factor for observing quantum effects and for harnessing them for quantum technologies. Here we propose a scheme for speeding up the generation of quantum entanglement between two coupled qubits by introducing a strong dissipation channel to one of these qubits. The maximal entanglement is conditionally established by evenly distributing a single excitat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.03084v1-abstract-full').style.display = 'inline'; document.getElementById('2410.03084v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.03084v1-abstract-full" style="display: none;"> Dissipation is usually considered a negative factor for observing quantum effects and for harnessing them for quantum technologies. Here we propose a scheme for speeding up the generation of quantum entanglement between two coupled qubits by introducing a strong dissipation channel to one of these qubits. The maximal entanglement is conditionally established by evenly distributing a single excitation between these two qubits. When the excitation is initially held by the dissipative qubit, the dissipation accelerates the excitation re-distribution process for the quantum state trajectory without quantum jumps. Our results show that the time needed to conditionally attain the maximal entanglement is monotonously decreased as the dissipative rate is increased. We further show that this scheme can be generalized to accelerate the production of the W state for the three-qubit system, where one NH qubit is symmetrically coupled to two Hermitian qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.03084v1-abstract-full').style.display = 'none'; document.getElementById('2410.03084v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">2 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.17442">arXiv:2409.17442</a> <span> [<a href="https://arxiv.org/pdf/2409.17442">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Optically Coherent Nitrogen-Vacancy Centers in HPHT Treated Diamonds </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tang%2C+Y">Yuan-Han Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xiaoran Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+K">Kang-Yuan Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Xia%2C+F">Fan Xia</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+H">Huijie Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xiaobing Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+H">Heng Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin 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="2409.17442v1-abstract-short" style="display: inline;"> As a point defect with unique spin and optical properties, nitrogen-vacancy (NV) center in diamond has attracted much attention in the fields of quantum sensing, quantum simulation, and quantum networks. The optical properties of an NV center are crucial for all these quantum applications. However, NV centers fabricated by destructive methods such as electron irradiation or ion implantation usuall… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.17442v1-abstract-full').style.display = 'inline'; document.getElementById('2409.17442v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.17442v1-abstract-full" style="display: none;"> As a point defect with unique spin and optical properties, nitrogen-vacancy (NV) center in diamond has attracted much attention in the fields of quantum sensing, quantum simulation, and quantum networks. The optical properties of an NV center are crucial for all these quantum applications. However, NV centers fabricated by destructive methods such as electron irradiation or ion implantation usually exhibit poor optical coherence. In this work, we demonstrate a non-destructive method to fabricate optically coherent NV centers. High-purity single crystal diamonds are annealed under high pressure and high temperature (1700 $^{\circ}$C, 5.5 GPa), and individually resolvable NV centers with narrow PLE linewidth (<100 MHz) are produced. The high-pressure condition prevents the conversion of diamond to graphite during high-temperature annealing, significantly expanding the parameter space for creating high-performance artificial defects for quantum information science. These findings deepen our understanding of NV center formation in diamond and have implications for the optimization of color centers in solids, including silicon carbide and hexagonal boron nitride. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.17442v1-abstract-full').style.display = 'none'; document.getElementById('2409.17442v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 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/2408.14112">arXiv:2408.14112</a> <span> [<a href="https://arxiv.org/pdf/2408.14112">pdf</a>, <a href="https://arxiv.org/format/2408.14112">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"> Dynamic compensation for pump-induced frequency shift in Kerr-cat qubit initialization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yifang Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+Z">Ziyue Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weiting Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yuwei Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jiajun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+J">Jie Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaoxuan Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+L">Lintao Xiao</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">Hongwei Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">Weizhou Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Ai%2C+H">Hao Ai</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yu-xi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+C">Chang-Ling Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luyan Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.14112v3-abstract-short" style="display: inline;"> The noise-biased Kerr-cat qubit is an attractive candidate for fault-tolerant quantum computation; however, its initialization faces challenges due to the squeezing pump-induced frequency shift (PIFS). Here, we propose and demonstrate a dynamic compensation method to mitigate the effect of PIFS during the Kerr-cat qubit initialization. Utilizing a novel nonlinearity-engineered triple-loop SQUID de… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14112v3-abstract-full').style.display = 'inline'; document.getElementById('2408.14112v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.14112v3-abstract-full" style="display: none;"> The noise-biased Kerr-cat qubit is an attractive candidate for fault-tolerant quantum computation; however, its initialization faces challenges due to the squeezing pump-induced frequency shift (PIFS). Here, we propose and demonstrate a dynamic compensation method to mitigate the effect of PIFS during the Kerr-cat qubit initialization. Utilizing a novel nonlinearity-engineered triple-loop SQUID device, we realize a stabilized Kerr-cat qubit and validate the advantages of the dynamic compensation method by improving the initialization fidelity from 57% to 78%, with a projected fidelity of 91% after excluding state preparation and measurement errors. Our results not only advance the practical implementation of Kerr-cat qubits, but also provide valuable insights into the fundamental adiabatic dynamics of these systems. This work paves the way for scalable quantum processors that leverage the bias-preserving properties of Kerr-cat qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14112v3-abstract-full').style.display = 'none'; document.getElementById('2408.14112v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.14076">arXiv:2408.14076</a> <span> [<a href="https://arxiv.org/pdf/2408.14076">pdf</a>, <a href="https://arxiv.org/format/2408.14076">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 transfer between superconducting cavities via exchange-free interactions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+J">Jie Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weiting Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">Weizhou Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+Z">Ziyue Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yifang Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaoxuan Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Xue%2C+G">Guangming Xue</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+H">Hongyi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yipu Song</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+H">Haifeng Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+C">Chang-Ling Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luyan Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.14076v1-abstract-short" style="display: inline;"> We propose and experimentally demonstrate a novel protocol for transferring quantum states between superconducting cavities using only continuous two-mode squeezing interactions, without exchange of photonic excitations between cavities. This approach conceptually resembles quantum teleportation, where quantum information is transferred between different nodes without directly transmitting carrier… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14076v1-abstract-full').style.display = 'inline'; document.getElementById('2408.14076v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.14076v1-abstract-full" style="display: none;"> We propose and experimentally demonstrate a novel protocol for transferring quantum states between superconducting cavities using only continuous two-mode squeezing interactions, without exchange of photonic excitations between cavities. This approach conceptually resembles quantum teleportation, where quantum information is transferred between different nodes without directly transmitting carrier photons. In contrast to the discrete operations of entanglement and Bell-state measurement in teleportation, our scheme is symmetric and continuous. We experimentally realize coherent and bidirectional transfer of arbitrary quantum states, including bosonic quantum error correction codes. Our results offer new insights into the quantum state transfer and quantum teleportation. In particular, our demonstration validates a new approach to realize quantum transducers, and might find applications in a wide range of physical platforms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14076v1-abstract-full').style.display = 'none'; document.getElementById('2408.14076v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.05435">arXiv:2408.05435</a> <span> [<a href="https://arxiv.org/pdf/2408.05435">pdf</a>, <a href="https://arxiv.org/format/2408.05435">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="Machine Learning">cs.LG</span> </div> </div> <p class="title is-5 mathjax"> SuperEncoder: Towards Universal Neural Approximate Quantum State Preparation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Yilun Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+B">Bingmeng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+W">Wenle Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiwei Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bing Li</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+Y">Yinhe Han</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Ying Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.05435v1-abstract-short" style="display: inline;"> Numerous quantum algorithms operate under the assumption that classical data has already been converted into quantum states, a process termed Quantum State Preparation (QSP). However, achieving precise QSP requires a circuit depth that scales exponentially with the number of qubits, making it a substantial obstacle in harnessing quantum advantage. Recent research suggests using a Parameterized Qua… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.05435v1-abstract-full').style.display = 'inline'; document.getElementById('2408.05435v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.05435v1-abstract-full" style="display: none;"> Numerous quantum algorithms operate under the assumption that classical data has already been converted into quantum states, a process termed Quantum State Preparation (QSP). However, achieving precise QSP requires a circuit depth that scales exponentially with the number of qubits, making it a substantial obstacle in harnessing quantum advantage. Recent research suggests using a Parameterized Quantum Circuit (PQC) to approximate a target state, offering a more scalable solution with reduced circuit depth compared to precise QSP. Despite this, the need for iterative updates of circuit parameters results in a lengthy runtime, limiting its practical application. In this work, we demonstrate that it is possible to leverage a pre-trained neural network to directly generate the QSP circuit for arbitrary quantum state, thereby eliminating the significant overhead of online iterations. Our study makes a steady step towards a universal neural designer for approximate QSP. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.05435v1-abstract-full').style.display = 'none'; document.getElementById('2408.05435v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.15102">arXiv:2407.15102</a> <span> [<a href="https://arxiv.org/pdf/2407.15102">pdf</a>, <a href="https://arxiv.org/format/2407.15102">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Experimental demonstration of reconstructing quantum states with generative models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xuegang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+W">Wenjie Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+Z">Ziyue Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weiting Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaoxuan Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">Weizhou Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Z">Zhide Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+J">Jiaxiu Han</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+R">Rebing Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+C">Chang-Ling Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+D">Dong-Ling Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luyan Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.15102v1-abstract-short" style="display: inline;"> Quantum state tomography, a process that reconstructs a quantum state from measurements on an ensemble of identically prepared copies, plays a crucial role in benchmarking quantum devices. However, brute-force approaches to quantum state tomography would become impractical for large systems, as the required resources scale exponentially with the system size. Here, we explore a machine learning app… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15102v1-abstract-full').style.display = 'inline'; document.getElementById('2407.15102v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.15102v1-abstract-full" style="display: none;"> Quantum state tomography, a process that reconstructs a quantum state from measurements on an ensemble of identically prepared copies, plays a crucial role in benchmarking quantum devices. However, brute-force approaches to quantum state tomography would become impractical for large systems, as the required resources scale exponentially with the system size. Here, we explore a machine learning approach and report an experimental demonstration of reconstructing quantum states based on neural network generative models with an array of programmable superconducting transmon qubits. In particular, we experimentally prepare the Greenberger-Horne-Zeilinger states and random states up to five qubits and demonstrate that the machine learning approach can efficiently reconstruct these states with the number of required experimental samples scaling linearly with system size. Our results experimentally showcase the intriguing potential for exploiting machine learning techniques in validating and characterizing complex quantum devices, offering a valuable guide for the future development of quantum technologies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15102v1-abstract-full').style.display = 'none'; document.getElementById('2407.15102v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.13317">arXiv:2404.13317</a> <span> [<a href="https://arxiv.org/pdf/2404.13317">pdf</a>, <a href="https://arxiv.org/format/2404.13317">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"> Unambiguous discrimination of general quantum operations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">Weizhou Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jing-Ning Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+Z">Ziyue Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weiting Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaoxuan Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xinyu Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yuwei Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+L">Ling Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Mu%2C+X">Xianghao Mu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haiyan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yipu Song</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+C">Chang-Ling Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luyan Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.13317v1-abstract-short" style="display: inline;"> The discrimination of quantum operations has long been an intriguing challenge, with theoretical research significantly advancing our understanding of the quantum features in discriminating quantum objects. This challenge is closely related to the discrimination of quantum states, and proof-of-principle demonstrations of the latter have already been realized using optical photons. However, the exp… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.13317v1-abstract-full').style.display = 'inline'; document.getElementById('2404.13317v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.13317v1-abstract-full" style="display: none;"> The discrimination of quantum operations has long been an intriguing challenge, with theoretical research significantly advancing our understanding of the quantum features in discriminating quantum objects. This challenge is closely related to the discrimination of quantum states, and proof-of-principle demonstrations of the latter have already been realized using optical photons. However, the experimental demonstration of discriminating general quantum operations, including both unitary and non-unitary operations, has remained elusive. In general quantum systems, especially those with high dimensions, the preparation of arbitrary quantum states and the implementation of arbitrary quantum operations and generalized measurements are non-trivial tasks. Here, for the first time, we experimentally demonstrate the optimal unambiguous discrimination of up to 6 displacement operators and the unambiguous discrimination of non-unitary quantum operations. Our results demonstrate powerful tools for experimental research in quantum information processing and are expected to stimulate a wide range of valuable applications in the field of quantum sensing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.13317v1-abstract-full').style.display = 'none'; document.getElementById('2404.13317v1-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 4 figures, 2 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.09390">arXiv:2404.09390</a> <span> [<a href="https://arxiv.org/pdf/2404.09390">pdf</a>, <a href="https://arxiv.org/ps/2404.09390">ps</a>, <a href="https://arxiv.org/format/2404.09390">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Skyrmion-mechanical hybrid quantum systems: Manipulation of skyrmion qubits via phonons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xue-Feng Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Hei%2C+X">Xin-Lei Hei</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+X">Xiao-Yu Yao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jia-Qiang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+Y">Yu-Meng Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+X">Xing-Liang Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Qiao%2C+Y">Yi-Fan Qiao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+P">Peng-Bo Li</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.09390v1-abstract-short" style="display: inline;"> Skyrmion qubits are a new highly promising logic element for quantum information processing. However, their scalability to multiple interacting qubits remains challenging. We propose a hybrid quantum setup with skyrmion qubits strongly coupled to nanomechanical cantilevers via magnetic coupling, which harnesses phonons as quantum interfaces for the manipulation of distant skyrmion qubits. A linear… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.09390v1-abstract-full').style.display = 'inline'; document.getElementById('2404.09390v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.09390v1-abstract-full" style="display: none;"> Skyrmion qubits are a new highly promising logic element for quantum information processing. However, their scalability to multiple interacting qubits remains challenging. We propose a hybrid quantum setup with skyrmion qubits strongly coupled to nanomechanical cantilevers via magnetic coupling, which harnesses phonons as quantum interfaces for the manipulation of distant skyrmion qubits. A linear drive is utilized to achieve the modulation of the stiffness coefficient of the cantilever, resulting in an exponential enhancement of the coupling strength between the skyrmion qubit and the mechanical mode. We also consider the case of a topological resonator array, which allows us to study interactions between skyrmion qubits and topological phonon band structure, as well as chiral skyrmion-skyrmion interactions. The scheme suggested here offers a fascinating platform for investigating quantum information processing and quantum simulation with magnetic microstructures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.09390v1-abstract-full').style.display = 'none'; document.getElementById('2404.09390v1-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">To appear in PR Research, 16 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.09388">arXiv:2404.09388</a> <span> [<a href="https://arxiv.org/pdf/2404.09388">pdf</a>, <a href="https://arxiv.org/ps/2404.09388">ps</a>, <a href="https://arxiv.org/format/2404.09388">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.132.193601">10.1103/PhysRevLett.132.193601 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Magnon-Skyrmion Hybrid Quantum Systems: Tailoring Interactions via Magnons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xue-Feng Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+P">Peng-Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Hei%2C+X">Xin-Lei Hei</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xichao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Mochizuki%2C+M">Masahito Mochizuki</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+F">Fu-Li Li</a>, <a href="/search/quant-ph?searchtype=author&query=Nori%2C+F">Franco Nori</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.09388v1-abstract-short" style="display: inline;"> Coherent and dissipative interactions between different quantum systems are essential for the construction of hybrid quantum systems and the investigation of novel quantum phenomena. Here, we propose and analyze a magnon-skyrmion hybrid quantum system, consisting of a micromagnet and nearby magnetic skyrmions. We predict a strong coupling mechanism between the magnonic mode of the micromagnet and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.09388v1-abstract-full').style.display = 'inline'; document.getElementById('2404.09388v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.09388v1-abstract-full" style="display: none;"> Coherent and dissipative interactions between different quantum systems are essential for the construction of hybrid quantum systems and the investigation of novel quantum phenomena. Here, we propose and analyze a magnon-skyrmion hybrid quantum system, consisting of a micromagnet and nearby magnetic skyrmions. We predict a strong coupling mechanism between the magnonic mode of the micromagnet and the quantized helicity degree of freedom of the skyrmion. We show that with this hybrid setup it is possible to induce magnon-mediated nonreciprocal interactions and responses between distant skyrmion qubits or between skyrmion qubits and other quantum systems like superconducting qubits. This work provides a quantum platform for the investigation of diverse quantum effects and quantum information processing with magnetic microstructures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.09388v1-abstract-full').style.display = 'none'; document.getElementById('2404.09388v1-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">To appear in PRL, 9 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 132, 193601 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.08342">arXiv:2404.08342</a> <span> [<a href="https://arxiv.org/pdf/2404.08342">pdf</a>, <a href="https://arxiv.org/format/2404.08342">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.22.034051">10.1103/PhysRevApplied.22.034051 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum integrated sensing and communication via entanglement </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yu-Chen Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+Y">Yuan-Bin Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xing-Bo Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+Z">Ze-Zhou Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+D">Dong Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Long%2C+G">Gui-Lu Long</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.08342v2-abstract-short" style="display: inline;"> Quantum communication and quantum metrology are widely compelling applications in the field of quantum information science, and quantum remote sensing is an intersection of both. Despite their differences, there are notable commonalities between quantum communication and quantum remote sensing, as they achieve their functionalities through the transmission of quantum states. Here we propose a nove… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.08342v2-abstract-full').style.display = 'inline'; document.getElementById('2404.08342v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.08342v2-abstract-full" style="display: none;"> Quantum communication and quantum metrology are widely compelling applications in the field of quantum information science, and quantum remote sensing is an intersection of both. Despite their differences, there are notable commonalities between quantum communication and quantum remote sensing, as they achieve their functionalities through the transmission of quantum states. Here we propose a novel quantum integrated sensing and communication (QISAC) protocol, which achieves quantum sensing under the Heisenberg limit while simultaneously enabling quantum secure communication through the transmission of entanglements. We have theoretically proven its security against eavesdroppers. The security of QISAC is characterized by the secrecy capacity for information bit as well as asymmetric Fisher information gain for sensing. Through simulations conducted under the constraints of limited entanglement resources, we illustrate that QISAC maintains high accuracy in the estimation of phase. Hence our QISAC offers a fresh perspective for the applications of future quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.08342v2-abstract-full').style.display = 'none'; document.getElementById('2404.08342v2-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review Applied 22 (3), 034051 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.02787">arXiv:2404.02787</a> <span> [<a href="https://arxiv.org/pdf/2404.02787">pdf</a>, <a href="https://arxiv.org/format/2404.02787">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"> Mixed-encoding one-photon-interference quantum secure direct communication </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xiangjie Li</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+Y">Yuanbin Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xingbo Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yunrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Long%2C+G">Guilu Long</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.02787v1-abstract-short" style="display: inline;"> Quantum secure direct communication (QSDC) guarantees both the security and reliability of information transmission using quantum states. One-photon-interference QSDC (OPI-QSDC) is a technique that enhances the transmission distance and ensures secure point-to-point information transmission, but it requires complex phase locking technology. This paper proposes a mixed-encoding one-photon-interfere… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.02787v1-abstract-full').style.display = 'inline'; document.getElementById('2404.02787v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.02787v1-abstract-full" style="display: none;"> Quantum secure direct communication (QSDC) guarantees both the security and reliability of information transmission using quantum states. One-photon-interference QSDC (OPI-QSDC) is a technique that enhances the transmission distance and ensures secure point-to-point information transmission, but it requires complex phase locking technology. This paper proposes a mixed-encoding one-photon-interference QSDC (MO-QSDC) protocol that removes the need for phase locking technology. Numerical simulations demonstrate that the MO-QSDC protocol could also beat the PLOB bound. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.02787v1-abstract-full').style.display = 'none'; document.getElementById('2404.02787v1-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.02780">arXiv:2404.02780</a> <span> [<a href="https://arxiv.org/pdf/2404.02780">pdf</a>, <a href="https://arxiv.org/format/2404.02780">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"> One-photon-interference quantum secure direct communication </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xiangjie Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+M">Min Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xingbo Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yunrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Long%2C+G">Guilu Long</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.02780v1-abstract-short" style="display: inline;"> Quantum secure direct communication (QSDC) is a quantum communication paradigm that transmits confidential messages directly using quantum states. Measurement-device-independent (MDI) QSDC protocols can eliminate the security loopholes associated with measurement devices. To enhance the practicality and performance of MDI-QSDC protocols, we propose a one-photon-interference MDI QSDC (OPI-QSDC) pro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.02780v1-abstract-full').style.display = 'inline'; document.getElementById('2404.02780v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.02780v1-abstract-full" style="display: none;"> Quantum secure direct communication (QSDC) is a quantum communication paradigm that transmits confidential messages directly using quantum states. Measurement-device-independent (MDI) QSDC protocols can eliminate the security loopholes associated with measurement devices. To enhance the practicality and performance of MDI-QSDC protocols, we propose a one-photon-interference MDI QSDC (OPI-QSDC) protocol which transcends the need for quantum memory, ideal single-photon sources, or entangled light sources. The security of our OPI-QSDC protocol has also been analyzed using quantum wiretap channel theory. Furthermore, our protocol could double the distance of usual prepare-and-measure protocols, since quantum states sending from adjacent nodes are connected with single-photon interference, which demonstrates its potential to extend the communication distance for point-to-point QSDC. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.02780v1-abstract-full').style.display = 'none'; document.getElementById('2404.02780v1-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.14967">arXiv:2403.14967</a> <span> [<a href="https://arxiv.org/pdf/2403.14967">pdf</a>, <a href="https://arxiv.org/format/2403.14967">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.6.010304">10.1103/PRXQuantum.6.010304 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Realization of versatile and effective quantum metrology using a single bosonic mode </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaozhou Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Krisnanda%2C+T">Tanjung Krisnanda</a>, <a href="/search/quant-ph?searchtype=author&query=Duina%2C+A">Andrea Duina</a>, <a href="/search/quant-ph?searchtype=author&query=Park%2C+K">Kimin Park</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+P">Pengtao Song</a>, <a href="/search/quant-ph?searchtype=author&query=Fontaine%2C+C+Y">Clara Yun Fontaine</a>, <a href="/search/quant-ph?searchtype=author&query=Copetudo%2C+A">Adrian Copetudo</a>, <a href="/search/quant-ph?searchtype=author&query=Filip%2C+R">Radim Filip</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+Y+Y">Yvonne Y. Gao</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.14967v2-abstract-short" style="display: inline;"> Quantum metrology offers the potential to surpass its classical counterpart, pushing the boundaries of measurement precision toward the ultimate Heisenberg limit. This enhanced precision is normally attained by utilizing large squeezed states or multi-particle entangled quantum states, both of which are often challenging to implement and prone to decoherence in real quantum devices. In this work,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.14967v2-abstract-full').style.display = 'inline'; document.getElementById('2403.14967v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.14967v2-abstract-full" style="display: none;"> Quantum metrology offers the potential to surpass its classical counterpart, pushing the boundaries of measurement precision toward the ultimate Heisenberg limit. This enhanced precision is normally attained by utilizing large squeezed states or multi-particle entangled quantum states, both of which are often challenging to implement and prone to decoherence in real quantum devices. In this work, we present a versatile and on-demand protocol for deterministic parameter estimation that leverages two efficient state-transfer operations on a single bosonic mode. Specifically, we demonstrate this protocol in the context of phase estimation using the superposition of coherent states in the bosonic circuit quantum electrodynamics (cQED) platform. With low average photon numbers of only up to 1.76, we achieve quantum-enhanced precision approaching the Heisenberg scaling, reaching a metrological gain of 7.5(6) dB. Importantly, we show that the gain or sensitivity range can be further enhanced on the fly by tailoring the input states, with different superposition weights, based on specific system constraints. The realization of this versatile and efficient scheme affords a promising path towards practical quantum-enhanced sensing, not only for bosonic cQED hardware but also readily extensible to other continuous-variable platforms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.14967v2-abstract-full').style.display = 'none'; document.getElementById('2403.14967v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main text (4 figures, 6 pages) and Appendices (11 figures and 1 table, 8 pages)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 6, 010304 (2025) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.13351">arXiv:2308.13351</a> <span> [<a href="https://arxiv.org/pdf/2308.13351">pdf</a>, <a href="https://arxiv.org/format/2308.13351">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"> Optically Detected Magnetic Resonance of Nitrogen-Vacancy Centers in Diamond under Weak Laser Excitation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yu%2C+Y">Yong-Hong Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+R">Rui-Zhi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yue Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+X">Xiu-Qi Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+H">Huijie Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Quan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Ren-Bao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Budker%2C+D">Dmitry Budker</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin 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="2308.13351v2-abstract-short" style="display: inline;"> As promising quantum sensors, nitrogen-vacancy (NV) centers in diamond have been widely used in frontier studies in condensed matter physics, material sciences, and life sciences. In practical applications, weak laser excitation is favorable as it reduces the side effects of laser irradiation, for example, phototoxicity and heating. Here we report a combined theoretical and experimental study of o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.13351v2-abstract-full').style.display = 'inline'; document.getElementById('2308.13351v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.13351v2-abstract-full" style="display: none;"> As promising quantum sensors, nitrogen-vacancy (NV) centers in diamond have been widely used in frontier studies in condensed matter physics, material sciences, and life sciences. In practical applications, weak laser excitation is favorable as it reduces the side effects of laser irradiation, for example, phototoxicity and heating. Here we report a combined theoretical and experimental study of optically detected magnetic resonance (ODMR) of NV-center ensembles under weak 532-nm laser excitation. In this regime, both the width and splitting of ODMR spectra decrease with increasing laser power. This power dependence is reproduced with a model considering laser-induced charge neutralization of NV--N+ pairs, which alters the local electric field environment. These results are important for understanding and designing NV-based quantum sensing in light-sensitive applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.13351v2-abstract-full').style.display = 'none'; document.getElementById('2308.13351v2-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.13027">arXiv:2302.13027</a> <span> [<a href="https://arxiv.org/pdf/2302.13027">pdf</a>, <a href="https://arxiv.org/format/2302.13027">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Protecting quantum entanglement between error-corrected logical qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">Weizhou Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Mu%2C+X">Xianghao Mu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weiting Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+J">Jie Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yuwei Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaoxuan Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+Z">Ziyue Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xinyu Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Xue%2C+G">Guangming Xue</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+H">Haifeng Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haiyan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yipu Song</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+C">Chang-Ling Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luyan Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.13027v1-abstract-short" style="display: inline;"> Entanglement represents one of the most important conceptual advances in physics during the last century and is also one of the most essential resources in quantum information science. However, entanglement is fragile and its potential advantages in applications are hindered by decoherence in practice. Here, we experimentally realize entangled logical qubits (ELQ) with a bosonic quantum module by… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.13027v1-abstract-full').style.display = 'inline'; document.getElementById('2302.13027v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.13027v1-abstract-full" style="display: none;"> Entanglement represents one of the most important conceptual advances in physics during the last century and is also one of the most essential resources in quantum information science. However, entanglement is fragile and its potential advantages in applications are hindered by decoherence in practice. Here, we experimentally realize entangled logical qubits (ELQ) with a bosonic quantum module by encoding quantum information into spatially separated microwave modes. The entanglement is protected by repetitive quantum error correction, and the coherence time of the purified ELQ via error detection is improved by 45$\%$ compared with the unprotected ELQ and exceeds that of the entangled physical qubits. In addition, violation of the Bell inequality by logical qubits is demonstrated for the first time with the measured Bell signal B=2.250$\pm$0.019 after purification, surpassing the classical bound by 13 standard deviations. The protected ELQ could be applied in future explorations of quantum foundations and applications of quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.13027v1-abstract-full').style.display = 'none'; document.getElementById('2302.13027v1-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 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">26 pages, 15 figures, 8 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2301.10424">arXiv:2301.10424</a> <span> [<a href="https://arxiv.org/pdf/2301.10424">pdf</a>, <a href="https://arxiv.org/ps/2301.10424">ps</a>, <a href="https://arxiv.org/format/2301.10424">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.130.073602">10.1103/PhysRevLett.130.073602 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Enhanced tripartite interactions in spin-magnon-mechanical hybrid systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hei%2C+X">Xin-Lei Hei</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+P">Peng-Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xue-Feng Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Nori%2C+F">Franco Nori</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="2301.10424v1-abstract-short" style="display: inline;"> Coherent tripartite interactions among degrees of freedom of completely different nature are instrumental for quantum information and simulation technologies, but they are generally difficult to realize and remain largely unexplored. Here, we predict a tripartite coupling mechanism in a hybrid setup comprising a single NV center and a micromagnet. We propose to realize direct and strong tripartite… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.10424v1-abstract-full').style.display = 'inline'; document.getElementById('2301.10424v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2301.10424v1-abstract-full" style="display: none;"> Coherent tripartite interactions among degrees of freedom of completely different nature are instrumental for quantum information and simulation technologies, but they are generally difficult to realize and remain largely unexplored. Here, we predict a tripartite coupling mechanism in a hybrid setup comprising a single NV center and a micromagnet. We propose to realize direct and strong tripartite interactions among single NV spins, magnons and phonons via modulating the relative motion between the NV center and the micromagnet. Specifically, by introducing a parametric drive (two-phonon drive) to modulate the mechanical motion (such as the center-of-mass motion of a NV spin in diamond trapped in an electrical trap or a levitated micromagnet in a magnetic trap), we can obtain a tunable and strong spin-magnon-phonon coupling at the single quantum level, with up to two orders of magnitude enhancement for the tripartite coupling strength. This enables, for example, tripartite entanglement among solid-state spins, magnons, and mechanical motions in quantum spin-magnonics-mechanics with realistic experimental parameters. This protocol can be readily implemented with the well-developed techniques in ion traps or magnetic traps, and could pave the way for general applications in quantum simulations and information processing based on directly and strongly coupled tripartite systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.10424v1-abstract-full').style.display = 'none'; document.getElementById('2301.10424v1-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 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 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">To appear in PRL, 9 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.02521">arXiv:2212.02521</a> <span> [<a href="https://arxiv.org/pdf/2212.02521">pdf</a>, <a href="https://arxiv.org/format/2212.02521">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-023-39785-8">10.1038/s41467-023-39785-8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Deep quantum neural networks equipped with backpropagation on a superconducting processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaoxuan Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Z">Zhide Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weiting Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+Z">Ziyue Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yifang Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Weikang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">Weizhou Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xuegang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haiyan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yi-Pu Song</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+C">Chang-Ling Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+D">Dong-Ling Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luyan Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.02521v1-abstract-short" style="display: inline;"> Deep learning and quantum computing have achieved dramatic progresses in recent years. The interplay between these two fast-growing fields gives rise to a new research frontier of quantum machine learning. In this work, we report the first experimental demonstration of training deep quantum neural networks via the backpropagation algorithm with a six-qubit programmable superconducting processor. I… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.02521v1-abstract-full').style.display = 'inline'; document.getElementById('2212.02521v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.02521v1-abstract-full" style="display: none;"> Deep learning and quantum computing have achieved dramatic progresses in recent years. The interplay between these two fast-growing fields gives rise to a new research frontier of quantum machine learning. In this work, we report the first experimental demonstration of training deep quantum neural networks via the backpropagation algorithm with a six-qubit programmable superconducting processor. In particular, we show that three-layer deep quantum neural networks can be trained efficiently to learn two-qubit quantum channels with a mean fidelity up to 96.0% and the ground state energy of molecular hydrogen with an accuracy up to 93.3% compared to the theoretical value. In addition, six-layer deep quantum neural networks can be trained in a similar fashion to achieve a mean fidelity up to 94.8% for learning single-qubit quantum channels. Our experimental results explicitly showcase the advantages of deep quantum neural networks, including quantum analogue of the backpropagation algorithm and less stringent coherence-time requirement for their constituting physical qubits, thus providing a valuable guide for quantum machine learning applications with both near-term and future quantum devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.02521v1-abstract-full').style.display = 'none'; document.getElementById('2212.02521v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages (main text) + 11 pages (Supplementary Information), 10 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications volume 14, Article number: 4006 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.01271">arXiv:2212.01271</a> <span> [<a href="https://arxiv.org/pdf/2212.01271">pdf</a>, <a href="https://arxiv.org/format/2212.01271">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Protecting the quantum interference of cat states by phase-space compression </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaozhou Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Schwinger%2C+J">Jonathan Schwinger</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+N">Ni-Ni Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+P">Pengtao Song</a>, <a href="/search/quant-ph?searchtype=author&query=Chua%2C+W">Weipin Chua</a>, <a href="/search/quant-ph?searchtype=author&query=Hanamura%2C+F">Fumiya Hanamura</a>, <a href="/search/quant-ph?searchtype=author&query=Joshi%2C+A">Atharv Joshi</a>, <a href="/search/quant-ph?searchtype=author&query=Valadares%2C+F">Fernando Valadares</a>, <a href="/search/quant-ph?searchtype=author&query=Filip%2C+R">Radim Filip</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+Y+Y">Yvonne Y. Gao</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.01271v1-abstract-short" style="display: inline;"> Cat states, with their unique phase-space interference properties, are ideal candidates for understanding fundamental principles of quantum mechanics and performing key quantum information processing tasks. However, they are highly susceptible to photon loss, which inevitably diminishes their quantum non-Gaussian features. Here, we protect these non-Gaussian features against photon loss by compres… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.01271v1-abstract-full').style.display = 'inline'; document.getElementById('2212.01271v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.01271v1-abstract-full" style="display: none;"> Cat states, with their unique phase-space interference properties, are ideal candidates for understanding fundamental principles of quantum mechanics and performing key quantum information processing tasks. However, they are highly susceptible to photon loss, which inevitably diminishes their quantum non-Gaussian features. Here, we protect these non-Gaussian features against photon loss by compressing the phase-space distribution of a cat state. We achieve this compression with a deterministic technique based on the echo conditional displacement operation in a circuit QED device. We present a versatile technique for creating robust non-Gaussian continuous-variable resource states in a highly linear bosonic mode and manipulating their phase-space distribution to achieve enhanced resilience against photon loss. Compressed cat states offer an attractive avenue for obtaining new insights into quantum foundations and quantum metrology, and for developing inherently more protected bosonic codewords for quantum error correction. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.01271v1-abstract-full').style.display = 'none'; document.getElementById('2212.01271v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 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">12 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.04751">arXiv:2210.04751</a> <span> [<a href="https://arxiv.org/pdf/2210.04751">pdf</a>, <a href="https://arxiv.org/ps/2210.04751">ps</a>, <a href="https://arxiv.org/format/2210.04751">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.107.023722">10.1103/PhysRevA.107.023722 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Enhanced spin-mechanical interaction with levitated micromagnets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xue-Feng Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Hei%2C+X">Xin-Lei Hei</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+X">Xing-Liang Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jia-Qiang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+C">Cai-Peng Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Ali%2C+H">Hamad Ali</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+P">Peng-Bo Li</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.04751v2-abstract-short" style="display: inline;"> Spin-mechanical hybrid systems have been widely used in quantum information processing. However, the spin-mechanical interaction is generally weak, making it a critical challenge to enhance the spin-mechanical interaction into the strong coupling or even ultra-strong coupling regime. Here, we propose a protocol that can significantly enhance the spin-mechanical coupling strength with a diamond spi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.04751v2-abstract-full').style.display = 'inline'; document.getElementById('2210.04751v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.04751v2-abstract-full" style="display: none;"> Spin-mechanical hybrid systems have been widely used in quantum information processing. However, the spin-mechanical interaction is generally weak, making it a critical challenge to enhance the spin-mechanical interaction into the strong coupling or even ultra-strong coupling regime. Here, we propose a protocol that can significantly enhance the spin-mechanical coupling strength with a diamond spin vacancy and a levitated micromagnet. A driving electrical current is used to modulate the mechanical motion of the levitated micromagnet, which induces a two-phonon drive and can exponentially enhance the spin-phonon and phonon-medicated spin-spin coupling strengths. Furthermore, a high fidelity Schrodinger cat state and an unconventional 2-qubit geometric phase gate with high fidelity and faster gate speed can be achieved using this hybrid system. This protocol provides a promising platform for quantum information processing with NV spins coupled to levitated micromagnets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.04751v2-abstract-full').style.display = 'none'; document.getElementById('2210.04751v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 October, 2022; <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> <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, 8 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.05064">arXiv:2204.05064</a> <span> [<a href="https://arxiv.org/pdf/2204.05064">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div 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/39/11/117601">10.1088/0256-307X/39/11/117601 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum sensing with diamond NV centers under megabar pressures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Dai%2C+J">Jian-Hong Dai</a>, <a href="/search/quant-ph?searchtype=author&query=Shang%2C+Y">Yan-Xing Shang</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+Y">Yong-Hong Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yue Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+H">Hui Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+F">Fang Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+X">Xiao-Hui Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin 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="2204.05064v1-abstract-short" style="display: inline;"> Megabar pressures are of crucial importance for cutting-edge studies of condensed matter physics and geophysics. With the development of diamond anvil cell, laboratory studies of high pressure have entered the megabar era for decades. However, it is still challenging to implement in-situ magnetic sensing under ultrahigh pressures. Here, we demonstrate optically detected magnetic resonance of diamo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.05064v1-abstract-full').style.display = 'inline'; document.getElementById('2204.05064v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.05064v1-abstract-full" style="display: none;"> Megabar pressures are of crucial importance for cutting-edge studies of condensed matter physics and geophysics. With the development of diamond anvil cell, laboratory studies of high pressure have entered the megabar era for decades. However, it is still challenging to implement in-situ magnetic sensing under ultrahigh pressures. Here, we demonstrate optically detected magnetic resonance of diamond nitrogen-vacancy (NV) centers, a promising quantum sensor of strain and magnetic fields, up to 1.4 Mbar. We quantify the reduction and blueshifts of NV fluorescence under high pressures. We demonstrate coherent manipulation of NV electron spins and extend its working pressure to the megabar region. These results shed new light on our understanding of diamond NV centers and will benefit quantum sensing under extreme conditions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.05064v1-abstract-full').style.display = 'none'; document.getElementById('2204.05064v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Chinese Physics Letters 39, 117601 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.10511">arXiv:2203.10511</a> <span> [<a href="https://arxiv.org/pdf/2203.10511">pdf</a>, <a href="https://arxiv.org/ps/2203.10511">ps</a>, <a href="https://arxiv.org/format/2203.10511">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-Pressure NMR Enabled by Diamond Nitrogen-Vacancy Centers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Shang%2C+Y">Yan-Xing Shang</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+F">Fang Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Dai%2C+J">Jian-Hong Dai</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Y">Ya-Nan Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+H">Hui Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+Y">Yong-Hong Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+X">Xiao-Hui Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin 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="2203.10511v1-abstract-short" style="display: inline;"> The integration of NMR and high pressure technique brings unique opportunities to study electronic, structural and dynamical properties under extreme conditions. Despite a great degree of success has been achieved using coil-based schemes, the contradictory requirement on sample volume of these two techniques remains an outstanding challenge. In this letter, we introduce diamond nitrogen-vacancy (… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.10511v1-abstract-full').style.display = 'inline'; document.getElementById('2203.10511v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.10511v1-abstract-full" style="display: none;"> The integration of NMR and high pressure technique brings unique opportunities to study electronic, structural and dynamical properties under extreme conditions. Despite a great degree of success has been achieved using coil-based schemes, the contradictory requirement on sample volume of these two techniques remains an outstanding challenge. In this letter, we introduce diamond nitrogen-vacancy (NV) centers, as the source and probe of in-situ nuclear spin polarization, to address the sample volume issue. We demonstrate hyperpolarization and coherent control of $^{14}$N nuclear spins under high pressures. NMR spectra of a micro-diamond are measured up to 16.6 GPa, and unexpected pressure shift of the $^{14}$N nuclear quadrupole and hyperfine coupling terms are observed. Our work contributes to quantum sensing enhanced spectrometry under extreme conditions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.10511v1-abstract-full').style.display = 'none'; document.getElementById('2203.10511v1-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 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.09080">arXiv:2203.09080</a> <span> [<a href="https://arxiv.org/pdf/2203.09080">pdf</a>, <a href="https://arxiv.org/format/2203.09080">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Experimental Quantum End-to-End Learning on a Superconducting Processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaoxuan Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+X">Xi Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weiting Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+Z">Ziyue Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">Weizhou Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xuegang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haiyan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+J">Jiaqi Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yipu Song</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+D">Dong-Ling Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+C">Chang-Ling Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+R">Re-Bing Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luyan Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.09080v1-abstract-short" style="display: inline;"> Machine learning can be substantially powered by a quantum computer owing to its huge Hilbert space and inherent quantum parallelism. In the pursuit of quantum advantages for machine learning with noisy intermediate-scale quantum devices, it was proposed that the learning model can be designed in an end-to-end fashion, i.e., the quantum ansatz is parameterized by directly manipulable control pulse… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.09080v1-abstract-full').style.display = 'inline'; document.getElementById('2203.09080v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.09080v1-abstract-full" style="display: none;"> Machine learning can be substantially powered by a quantum computer owing to its huge Hilbert space and inherent quantum parallelism. In the pursuit of quantum advantages for machine learning with noisy intermediate-scale quantum devices, it was proposed that the learning model can be designed in an end-to-end fashion, i.e., the quantum ansatz is parameterized by directly manipulable control pulses without circuit design and compilation. Such gate-free models are hardware friendly and can fully exploit limited quantum resources. Here, we report the first experimental realization of quantum end-to-end machine learning on a superconducting processor. The trained model can achieve 98% recognition accuracy for two handwritten digits (via two qubits) and 89% for four digits (via three qubits) in the MNIST (Mixed National Institute of Standards and Technology) database. The experimental results exhibit the great potential of quantum end-to-end learning for resolving complex real-world tasks when more qubits are available. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.09080v1-abstract-full').style.display = 'none'; document.getElementById('2203.09080v1-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 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 4 figures and supplement</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">MSC Class:</span> 81P05 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.01435">arXiv:2202.01435</a> <span> [<a href="https://arxiv.org/pdf/2202.01435">pdf</a>, <a href="https://arxiv.org/format/2202.01435">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> <div 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/s41467-022-34727-2">10.1038/s41467-022-34727-2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Engineering superconducting qubits to reduce quasiparticles and charge noise </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xianchuang Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yuxuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haolan Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Nie%2C+L">Lifu Nie</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+W">Weiwei Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Libo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Jian Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Song Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+Z+H">Zhi Hao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Catelani%2C+G">Gianluigi Catelani</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+L">Ling Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+F">Fei Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+D">Dapeng Yu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2202.01435v2-abstract-short" style="display: inline;"> Identifying, quantifying, and suppressing decoherence mechanisms in qubits are important steps towards the goal of engineering a quantum computer or simulator. Superconducting circuits offer flexibility in qubit design; however, their performance is adversely affected by quasiparticles (broken Cooper pairs). Developing a quasiparticle mitigation strategy compatible with scalable, high-coherence de… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.01435v2-abstract-full').style.display = 'inline'; document.getElementById('2202.01435v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.01435v2-abstract-full" style="display: none;"> Identifying, quantifying, and suppressing decoherence mechanisms in qubits are important steps towards the goal of engineering a quantum computer or simulator. Superconducting circuits offer flexibility in qubit design; however, their performance is adversely affected by quasiparticles (broken Cooper pairs). Developing a quasiparticle mitigation strategy compatible with scalable, high-coherence devices is therefore highly desirable. Here we experimentally demonstrate how to control quasiparticle generation by downsizing the qubit, capping it with a metallic cover, and equipping it with suitable quasiparticle traps. Using a flip-chip design, we shape the electromagnetic environment of the qubit above the superconducting gap, inhibiting quasiparticle poisoning. Our findings support the hypothesis that quasiparticle generation is dominated by the breaking of Cooper pairs at the junction, as a result of photon absorption by the antenna-like qubit structure. We achieve record low charge-parity switching rate (<1Hz). Our aluminium devices also display improved stability with respect to discrete charging events. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.01435v2-abstract-full').style.display = 'none'; document.getElementById('2202.01435v2-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 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 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> Nat. Commun. 13, 7196 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2112.14922">arXiv:2112.14922</a> <span> [<a href="https://arxiv.org/pdf/2112.14922">pdf</a>, <a href="https://arxiv.org/format/2112.14922">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/s41567-022-01813-7">10.1038/s41567-022-01813-7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Scalable algorithm simplification using quantum AND logic </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chu%2C+J">Ji Chu</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+X">Xiaoyu He</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yuxuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+J">Jiahao Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Libo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Q">Qihao Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Hai%2C+Y">Yongju Hai</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+Z">Zhikun Han</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+C">Chang-Kang Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+W">Wenhui Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+H">Hao Jia</a>, <a href="/search/quant-ph?searchtype=author&query=Jiao%2C+D">Dawei Jiao</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Ni%2C+Z">Zhongchu Ni</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xianchuang Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+J">Jiawei Qiu</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+W">Weiwei Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Z">Zusheng Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jiajian Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhida Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+W">Wanjing Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yuanzhen Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+X">Xiaowei Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+X">Xiuhao Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+L">Ling Hu</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="2112.14922v1-abstract-short" style="display: inline;"> Implementing quantum algorithms on realistic hardware requires translating high-level global operations into sequences of native elementary gates, a process known as quantum compiling. Physical limitations, such as constraints in connectivity and gate alphabets, often result in unacceptable implementation costs. To enable successful near-term applications, it is crucial to optimize compilation by… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.14922v1-abstract-full').style.display = 'inline'; document.getElementById('2112.14922v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2112.14922v1-abstract-full" style="display: none;"> Implementing quantum algorithms on realistic hardware requires translating high-level global operations into sequences of native elementary gates, a process known as quantum compiling. Physical limitations, such as constraints in connectivity and gate alphabets, often result in unacceptable implementation costs. To enable successful near-term applications, it is crucial to optimize compilation by exploiting the potential capabilities of existing hardware. Here, we implement a resource-efficient construction for a quantum version of AND logic that can reduce the cost, enabling the execution of key quantum circuits. On a high-scalability superconducting quantum processor, we demonstrate low-depth synthesis of high-fidelity generalized Toffoli gates with up to 8 qubits and Grover's search algorithm in a search space of up to 64 entries; both are the largest such implementations in scale to date. Our experimental demonstration illustrates a scalable implementation of simplifying quantum algorithms, paving the way for larger, more meaningful quantum applications on noisy devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.14922v1-abstract-full').style.display = 'none'; document.getElementById('2112.14922v1-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 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> Nature Physics 19, 126 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.04298">arXiv:2108.04298</a> <span> [<a href="https://arxiv.org/pdf/2108.04298">pdf</a>, <a href="https://arxiv.org/format/2108.04298">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/ac8444">10.1088/2058-9565/ac8444 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimal charging of a superconducting quantum battery </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hu%2C+C">Chang-Kang Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+J">Jiawei Qiu</a>, <a href="/search/quant-ph?searchtype=author&query=Souza%2C+P+J+P">Paulo J. P. Souza</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+J">Jiahao Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yuxuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Libo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chu%2C+J">Ji Chu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xianchuang Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+L">Ling Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Jian Li</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yuan Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhong%2C+Y">Youpeng Zhong</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Song Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+F">Fei Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Tan%2C+D">Dian Tan</a>, <a href="/search/quant-ph?searchtype=author&query=Bachelard%2C+R">R. Bachelard</a>, <a href="/search/quant-ph?searchtype=author&query=Villas-Boas%2C+C+J">C. J. Villas-Boas</a>, <a href="/search/quant-ph?searchtype=author&query=Santos%2C+A+C">Alan C. Santos</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+D">Dapeng Yu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.04298v2-abstract-short" style="display: inline;"> Quantum batteries are miniature energy storage devices and play a very important role in quantum thermodynamics. In recent years, quantum batteries have been extensively studied, but limited in theoretical level. Here we report the experimental realization of a quantum battery based on superconducting qubits. Our model explores dark and bright states to achieve stable and powerful charging process… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.04298v2-abstract-full').style.display = 'inline'; document.getElementById('2108.04298v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.04298v2-abstract-full" style="display: none;"> Quantum batteries are miniature energy storage devices and play a very important role in quantum thermodynamics. In recent years, quantum batteries have been extensively studied, but limited in theoretical level. Here we report the experimental realization of a quantum battery based on superconducting qubits. Our model explores dark and bright states to achieve stable and powerful charging processes, respectively. Our scheme makes use of the quantum adiabatic brachistochrone, which allows us to speed up the {battery ergotropy injection. Due to the inherent interaction of the system with its surrounding, the battery exhibits a self-discharge, which is shown to be described by a supercapacitor-like self-discharging mechanism. Our results paves the way for proposals of new superconducting circuits able to store extractable work for further usage. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.04298v2-abstract-full').style.display = 'none'; document.getElementById('2108.04298v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 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">5 pages and 3 figures + Supplemental material</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Science and Technology 7, 045018 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.08978">arXiv:2104.08978</a> <span> [<a href="https://arxiv.org/pdf/2104.08978">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/sciadv.abi6699">10.1126/sciadv.abi6699 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Capturing 3D atomic defects and phonon localization at the 2D heterostructure interface </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tian%2C+X">Xuezeng Tian</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+X">Xingxu Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Varnavides%2C+G">Georgios Varnavides</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+Y">Yakun Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+D+S">Dennis S. Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Ciccarino%2C+C+J">Christopher J. Ciccarino</a>, <a href="/search/quant-ph?searchtype=author&query=Anikeeva%2C+P">Polina Anikeeva</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming-Yang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+L">Lain-Jong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Narang%2C+P">Prineha Narang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaoqing Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Miao%2C+J">Jianwei Miao</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="2104.08978v1-abstract-short" style="display: inline;"> The 3D local atomic structures and crystal defects at the interfaces of heterostructures control their electronic, magnetic, optical, catalytic and topological quantum properties, but have thus far eluded any direct experimental determination. Here we determine the 3D local atomic positions at the interface of a MoS2-WSe2 heterojunction with picometer precision and correlate 3D atomic defects with… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.08978v1-abstract-full').style.display = 'inline'; document.getElementById('2104.08978v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.08978v1-abstract-full" style="display: none;"> The 3D local atomic structures and crystal defects at the interfaces of heterostructures control their electronic, magnetic, optical, catalytic and topological quantum properties, but have thus far eluded any direct experimental determination. Here we determine the 3D local atomic positions at the interface of a MoS2-WSe2 heterojunction with picometer precision and correlate 3D atomic defects with localized vibrational properties at the epitaxial interface. We observe point defects, bond distortion, atomic-scale ripples and measure the full 3D strain tensor at the heterointerface. By using the experimental 3D atomic coordinates as direct input to first principles calculations, we reveal new phonon modes localized at the interface, which are corroborated by spatially resolved electron energy-loss spectroscopy. We expect that this work will open the door to correlate structure-property relationships of a wide range of heterostructure interfaces at the single-atom level. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.08978v1-abstract-full').style.display = 'none'; document.getElementById('2104.08978v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Sci. Adv. 7, eabi6699 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.02669">arXiv:2104.02669</a> <span> [<a href="https://arxiv.org/pdf/2104.02669">pdf</a>, <a href="https://arxiv.org/format/2104.02669">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div 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.16.054047">10.1103/PhysRevApplied.16.054047 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Suppressing Coherent Two-Qubit Errors via Dynamical Decoupling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+J">Jiawei Qiu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yuxuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+C">Chang-Kang Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+J">Jiahao Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Libo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chu%2C+J">Ji Chu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+W">Wenhui Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Weiyang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+K">Kai Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Ni%2C+Z">Zhongchu Ni</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xianchuang Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Z">Zhixuan Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yimeng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yuanzhen Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+X">Xiu-Hao Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+L">Ling Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Jian Li</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+J">Jingjing Niu</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yuan Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+T">Tongxing Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhong%2C+Y">Youpeng Zhong</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Song Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+F">Fei Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+D">Dapeng Yu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.02669v1-abstract-short" style="display: inline;"> Scalable quantum information processing requires the ability to tune multi-qubit interactions. This makes the precise manipulation of quantum states particularly difficult for multi-qubit interactions because tunability unavoidably introduces sensitivity to fluctuations in the tuned parameters, leading to erroneous multi-qubit gate operations. The performance of quantum algorithms may be severely… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.02669v1-abstract-full').style.display = 'inline'; document.getElementById('2104.02669v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.02669v1-abstract-full" style="display: none;"> Scalable quantum information processing requires the ability to tune multi-qubit interactions. This makes the precise manipulation of quantum states particularly difficult for multi-qubit interactions because tunability unavoidably introduces sensitivity to fluctuations in the tuned parameters, leading to erroneous multi-qubit gate operations. The performance of quantum algorithms may be severely compromised by coherent multi-qubit errors. It is therefore imperative to understand how these fluctuations affect multi-qubit interactions and, more importantly, to mitigate their influence. In this study, we demonstrate how to implement dynamical-decoupling techniques to suppress the two-qubit analogue of the dephasing on a superconducting quantum device featuring a compact tunable coupler, a trending technology that enables the fast manipulation of qubit--qubit interactions. The pure-dephasing time shows an up to ~14 times enhancement on average when using robust sequences. The results are in good agreement with the noise generated from room-temperature circuits. Our study further reveals the decohering processes associated with tunable couplers and establishes a framework to develop gates and sequences robust against two-qubit errors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.02669v1-abstract-full').style.display = 'none'; document.getElementById('2104.02669v1-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 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">19 pages, 14 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 16, 054047 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.05134">arXiv:2012.05134</a> <span> [<a href="https://arxiv.org/pdf/2012.05134">pdf</a>, <a href="https://arxiv.org/format/2012.05134">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0052239">10.1063/5.0052239 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Temperature insensitive type II quasi-phasematched spontaneous parametric downconversion </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yi Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Kurtsiefer%2C+C">Christian Kurtsiefer</a>, <a href="/search/quant-ph?searchtype=author&query=Ling%2C+A">Alexander Ling</a>, <a href="/search/quant-ph?searchtype=author&query=Grieve%2C+J+A">James A. Grieve</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="2012.05134v1-abstract-short" style="display: inline;"> The temperature dependence of the refractive indices of potassium titanyl phosphate (KTP) are shown to enable quasi-phasematched type II spontaneous parametric downconversion (SPDC) with low temperature sensitivity. Calculations show the effect to be maximised for emission of photons at around 1165nm, as well as producing potentially useful regions for wavelengths throughout the telecommunications… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.05134v1-abstract-full').style.display = 'inline'; document.getElementById('2012.05134v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.05134v1-abstract-full" style="display: none;"> The temperature dependence of the refractive indices of potassium titanyl phosphate (KTP) are shown to enable quasi-phasematched type II spontaneous parametric downconversion (SPDC) with low temperature sensitivity. Calculations show the effect to be maximised for emission of photons at around 1165nm, as well as producing potentially useful regions for wavelengths throughout the telecommunications bands. We demonstrate the effect experimentally, observing temperature-insensitive degenerate emission at 1326nm, within the telecommunications O band. This result has practical applications in the development of entangled photon sources for resource-constrained environments, and we demonstrate a simple polarization entangled source as a proof of concept. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.05134v1-abstract-full').style.display = 'none'; document.getElementById('2012.05134v1-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 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 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/2005.09849">arXiv:2005.09849</a> <span> [<a href="https://arxiv.org/pdf/2005.09849">pdf</a>, <a href="https://arxiv.org/format/2005.09849">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.125.180503">10.1103/PhysRevLett.125.180503 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Manipulating complex hybrid entanglement and testing multipartite Bell inequalities in a superconducting circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yuwei Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaoxuan Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">Weizhou Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Mu%2C+X">Xianghao Mu</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yuan Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+L">Ling Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weiting Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haiyan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y+P">Yi Pu Song</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Z">Zhen-Biao Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+S">Shi-Biao Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luyan Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2005.09849v1-abstract-short" style="display: inline;"> Quantum correlations in observables of multiple systems not only are of fundamental interest, but also play a key role in quantum information processing. As a signature of these correlations, the violation of Bell inequalities has not been demonstrated with multipartite hybrid entanglement involving both continuous and discrete variables. Here we create a five-partite entangled state with three su… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.09849v1-abstract-full').style.display = 'inline'; document.getElementById('2005.09849v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2005.09849v1-abstract-full" style="display: none;"> Quantum correlations in observables of multiple systems not only are of fundamental interest, but also play a key role in quantum information processing. As a signature of these correlations, the violation of Bell inequalities has not been demonstrated with multipartite hybrid entanglement involving both continuous and discrete variables. Here we create a five-partite entangled state with three superconducting transmon qubits and two photonic qubits, each encoded in the mesoscopic field of a microwave cavity. We reveal the quantum correlations among these distinct elements by joint Wigner tomography of the two cavity fields conditional on the detection of the qubits and by test of a five-partite Bell inequality. The measured Bell signal is $8.381\pm0.038$, surpassing the bound of 8 for a four-partite entanglement imposed by quantum correlations by 10 standard deviations, demonstrating the genuine five-partite entanglement in a hybrid quantum system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.09849v1-abstract-full').style.display = 'none'; document.getElementById('2005.09849v1-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 May, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 figures and supplement</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 125, 180503 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2005.03656">arXiv:2005.03656</a> <span> [<a href="https://arxiv.org/pdf/2005.03656">pdf</a>, <a href="https://arxiv.org/format/2005.03656">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic and Molecular Clusters">physics.atm-clus</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.125.263002">10.1103/PhysRevLett.125.263002 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Chiral Induced Spin Selectivity as a Spontaneous Intertwined Order </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xiaopeng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Nan%2C+J">Jue Nan</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiangcheng 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="2005.03656v2-abstract-short" style="display: inline;"> Chiral induced spin selectivity (CISS) describes efficient spin filtering by chiral molecules. This phenomenon has led to nanoscale manipulation of quantum spins with promising applications to spintronics and quantum computing, since its discovery nearly two decades ago. However, its underlying mechanism still remains mysterious for the required spin-orbit interaction (SOI) strength is unexpectedl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.03656v2-abstract-full').style.display = 'inline'; document.getElementById('2005.03656v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2005.03656v2-abstract-full" style="display: none;"> Chiral induced spin selectivity (CISS) describes efficient spin filtering by chiral molecules. This phenomenon has led to nanoscale manipulation of quantum spins with promising applications to spintronics and quantum computing, since its discovery nearly two decades ago. However, its underlying mechanism still remains mysterious for the required spin-orbit interaction (SOI) strength is unexpectedly large. Here we report a multi-orbital theory for CISS, where an effective SOI emerges from spontaneous formation of electron-hole pairing caused by many-body correlation. This mechanism produces a strong SOI to the order of tens of milielectronvolts which could support the large spin polarization observed in CISS at room temperature. One central ingredient of our theory is the Wannier functions of the valence and conduction bands correspond respectively to one- and two-dimensional representation of the spatial rotation symmetry around the molecule elongation direction. The induced SOI strength is found to decrease when the band gap increases. Our theory may provide important guidance for searching other molecules with CISS effects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.03656v2-abstract-full').style.display = 'none'; document.getElementById('2005.03656v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 May, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 125, 263002 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.10721">arXiv:1912.10721</a> <span> [<a href="https://arxiv.org/pdf/1912.10721">pdf</a>, <a href="https://arxiv.org/format/1912.10721">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> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.14.024070">10.1103/PhysRevApplied.14.024070 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tunable coupler for realizing a controlled-phase gate with dynamically decoupled regime in a superconducting circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">X. Li</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+T">T. Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+H">H. Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Z. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">X. Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Y. Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">W. Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+J">J. Han</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+Z">Z. Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+X">X. Han</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Y. Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+H">H. Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yipu Song</a>, <a href="/search/quant-ph?searchtype=author&query=Duan%2C+L">Luming Duan</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luyan Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.10721v3-abstract-short" style="display: inline;"> Controllable interaction between superconducting qubits is desirable for large-scale quantum computation and simulation. Here, based on a theoretical proposal by Yan et al. [Phys. Rev. Appl. 10, 054061 (2018)] we experimentally demonstrate a simply-designed and flux-controlled tunable coupler with a continuous tunability by adjusting the coupler frequency, which can completely turn off adjacent su… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.10721v3-abstract-full').style.display = 'inline'; document.getElementById('1912.10721v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.10721v3-abstract-full" style="display: none;"> Controllable interaction between superconducting qubits is desirable for large-scale quantum computation and simulation. Here, based on a theoretical proposal by Yan et al. [Phys. Rev. Appl. 10, 054061 (2018)] we experimentally demonstrate a simply-designed and flux-controlled tunable coupler with a continuous tunability by adjusting the coupler frequency, which can completely turn off adjacent superconducting qubit coupling. Utilizing the tunable interaction between two qubits via the coupler, we implement a different type of controlled-phase (CZ) gate with 'dynamically decoupled regime', which allows the qubit-qubit coupling to be only 'on' at the usual operating point while dynamically 'off' during the tuning process of one qubit frequency into and out of the operating point. This scheme not only efficiently suppresses the leakage out of the computational subspace, but also allows for the acquired two-qubit phase being geometric at the operating point. We achieve an average CZ gate fidelity of 98.3(0.6), which is dominantly limited by qubit decoherence. The demonstrated tunable coupler provides a desirable tool to suppress adjacent qubit coupling and is suitable for large scale quantum computation and simulation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.10721v3-abstract-full').style.display = 'none'; document.getElementById('1912.10721v3-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, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">4 pages and 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 14, 024070 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.00845">arXiv:1912.00845</a> <span> [<a href="https://arxiv.org/pdf/1912.00845">pdf</a>, <a href="https://arxiv.org/ps/1912.00845">ps</a>, <a href="https://arxiv.org/format/1912.00845">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.124.210502">10.1103/PhysRevLett.124.210502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observing information backflow from controllable non-Markovian multi-channels in diamond </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Y">Yanan Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yuran Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gangqin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Nori%2C+F">Franco Nori</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+H">Heng Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xinyu 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="1912.00845v1-abstract-short" style="display: inline;"> Any realistic quantum system is inevitably subject to an external environment. This environment makes the open-system dynamics significant for many quantum tech-nologies, such as entangled-state engineering, quantum simulation, and quantum sensing. The information flow of a system to its environment usually induces a Markovian process, while the backflow of information from the environment exhibit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.00845v1-abstract-full').style.display = 'inline'; document.getElementById('1912.00845v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.00845v1-abstract-full" style="display: none;"> Any realistic quantum system is inevitably subject to an external environment. This environment makes the open-system dynamics significant for many quantum tech-nologies, such as entangled-state engineering, quantum simulation, and quantum sensing. The information flow of a system to its environment usually induces a Markovian process, while the backflow of information from the environment exhibits non-Markovianity. The practical environment, usually consisting of a large number of degrees of freedom, is hard to control, despite some attempts on controllable transitions from Markovian to non-Markovian dynamics. Here, we experimentally demonstrate the engineering of multiple dissipative channels by controlling the adjacent nuclear spins of a nitrogen-vacancy centre in diamond. With a controllable non-Markovian dynamics of the open system, we observe that the quantum Fisher information flows to and from the environment using different noisy channels. Our work contributes to the developments of both noisy quantum metrology and quantum open systems from the view points of metrologically useful entanglement. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.00845v1-abstract-full').style.display = 'none'; document.getElementById('1912.00845v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages,6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1910.12271">arXiv:1910.12271</a> <span> [<a href="https://arxiv.org/pdf/1910.12271">pdf</a>, <a href="https://arxiv.org/format/1910.12271">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.124.230503">10.1103/PhysRevLett.124.230503 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental implementation of universal nonadiabatic geometric quantum gates in a superconducting circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yuan Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+Z">Ziyue Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Tao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiaoxuan Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xuegang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+J">Jiaxiu Han</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">Weizhou Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yuwei Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haiyan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yipu Song</a>, <a href="/search/quant-ph?searchtype=author&query=Xue%2C+Z">Zheng-Yuan Xue</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luyan Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1910.12271v2-abstract-short" style="display: inline;"> Using geometric phases to realize noise-resilient quantum computing is an important method to enhance the control fidelity. In this work, we experimentally realize a universal nonadiabatic geometric quantum gate set in a superconducting qubit chain. We characterize the realized single- and two-qubit geometric gates with both quantum process tomography and randomized benchmarking methods. The measu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.12271v2-abstract-full').style.display = 'inline'; document.getElementById('1910.12271v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.12271v2-abstract-full" style="display: none;"> Using geometric phases to realize noise-resilient quantum computing is an important method to enhance the control fidelity. In this work, we experimentally realize a universal nonadiabatic geometric quantum gate set in a superconducting qubit chain. We characterize the realized single- and two-qubit geometric gates with both quantum process tomography and randomized benchmarking methods. The measured average fidelities for the single-qubit rotation gates and two-qubit controlled-Z gate are 0.9977(1) and 0.977(9), respectively. Besides, we also experimentally demonstrate the noise-resilient feature of the realized single-qubit geometric gates by comparing their performance with the conventional dynamical gates with different types of errors in the control field. Thus, our experiment proves a way to achieve high-fidelity geometric quantum gates for robust quantum computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.12271v2-abstract-full').style.display = 'none'; document.getElementById('1910.12271v2-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 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 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">Main text: 7 pages, 4 figures; Supplement: 5 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 124, 230503 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1909.06803">arXiv:1909.06803</a> <span> [<a href="https://arxiv.org/pdf/1909.06803">pdf</a>, <a href="https://arxiv.org/format/1909.06803">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/s41567-020-0893-x">10.1038/s41567-020-0893-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Error-transparent operations on a logical qubit protected by quantum error correction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Y. Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Y. Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Mu%2C+X">X. Mu</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+W">W. Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+L">L. Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">W. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">X. Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y+P">Y. P. Song</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+C+-">C. -L. Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">L. Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1909.06803v1-abstract-short" style="display: inline;"> Universal quantum computation is striking for its unprecedented capability in processing information, but its scalability is challenging in practice because of the inevitable environment noise. Although quantum error correction (QEC) techniques have been developed to protect stored quantum information from leading orders of errors, the noise-resilient processing of the QEC-protected quantum inform… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1909.06803v1-abstract-full').style.display = 'inline'; document.getElementById('1909.06803v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1909.06803v1-abstract-full" style="display: none;"> Universal quantum computation is striking for its unprecedented capability in processing information, but its scalability is challenging in practice because of the inevitable environment noise. Although quantum error correction (QEC) techniques have been developed to protect stored quantum information from leading orders of errors, the noise-resilient processing of the QEC-protected quantum information is highly demanded but remains elusive. Here, we demonstrate phase gate operations on a logical qubit encoded in a bosonic oscillator in an error-transparent (ET) manner. Inspired by Refs. [9,10], the ET gates are extended to the bosonic code and are able to tolerate errors during the gate operations, regardless of the random occurrence time of the error. With precisely designed gate Hamiltonians through photon-number-resolved AC-Stark shifts, the ET condition is fulfilled experimentally. We verify that the ET gates outperform the non-ET gates with a substantial improvement of the gate fidelity after an occurrence of the single-photon-loss error. Our ET gates in the superconducting quantum circuits are readily for extending to multiple encoded qubits and a universal gate set is within reach, paving the way towards fault-tolerant quantum computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1909.06803v1-abstract-full').style.display = 'none'; document.getElementById('1909.06803v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 September, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">6 pages, 4 figures and supplement</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Physics 16, 827-831 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1806.02181">arXiv:1806.02181</a> <span> [<a href="https://arxiv.org/pdf/1806.02181">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </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/s41467-019-08544-z">10.1038/s41467-019-08544-z <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High-resolution spectroscopy of single nuclear spins via sequential weak measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pfender%2C+M">Matthias Pfender</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+P">Ping Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Sumiya%2C+H">Hitoshi Sumiya</a>, <a href="/search/quant-ph?searchtype=author&query=Onoda%2C+S">Shinobu Onoda</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+W">Wen Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Dasari%2C+D+B+R">Durga Bhaktavatsala Rao Dasari</a>, <a href="/search/quant-ph?searchtype=author&query=Neumann%2C+P">Philipp Neumann</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Isoya%2C+J">Junichi Isoya</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Ren-Bao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wrachtrup%2C+J">J. Wrachtrup</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="1806.02181v2-abstract-short" style="display: inline;"> Quantum sensors have recently achieved to detect the magnetic moment of few or single nuclear spins and measure their magnetic resonance (NMR) signal. However, the spectral resolution, a key feature of NMR, has been limited by relaxation of the sensor to a few kHz at room temperature. The spectral resolution of NMR signals from single nuclear spins can be improved by, e.g., using quantum memories,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1806.02181v2-abstract-full').style.display = 'inline'; document.getElementById('1806.02181v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1806.02181v2-abstract-full" style="display: none;"> Quantum sensors have recently achieved to detect the magnetic moment of few or single nuclear spins and measure their magnetic resonance (NMR) signal. However, the spectral resolution, a key feature of NMR, has been limited by relaxation of the sensor to a few kHz at room temperature. The spectral resolution of NMR signals from single nuclear spins can be improved by, e.g., using quantum memories, however at the expense of sensitivity. Classical signals on the other hand can be measured with exceptional spectral resolution by using continuous measurement techniques, without compromising sensitivity. To apply these techniques to single-spin NMR, it is critical to overcome the impact of back action inherent of quantum measurements. Here we report sequential weak measurements on a single $^{13}$C nuclear spin. The back-action of repetitive weak measurements causes the spin to undergo a quantum dynamics phase transition from coherent trapping to coherent oscillation. Single-spin NMR at room-temperature with a spectral resolution of 3.8 Hz is achieved. These results enable the use of measurement-correlation schemes for the detection of very weakly coupled single spins. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1806.02181v2-abstract-full').style.display = 'none'; document.getElementById('1806.02181v2-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 August, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 June, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2018. </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">Article: 16 pages, 4 figures Supplementary: 23 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1612.07944">arXiv:1612.07944</a> <span> [<a href="https://arxiv.org/pdf/1612.07944">pdf</a>, <a href="https://arxiv.org/ps/1612.07944">ps</a>, <a href="https://arxiv.org/format/1612.07944">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.118.150504">10.1103/PhysRevLett.118.150504 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Single-Shot Readout of a Nuclear Spin Weakly Coupled to a Nitrogen-Vacancy Center </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Xing%2C+J">Jian Xing</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+W">Wen-Long Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chang-Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+P">Ping Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Po%2C+H+C">Hoi Chun Po</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Ren-Bao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu 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="1612.07944v1-abstract-short" style="display: inline;"> Single-shot readout of qubits is required for scalable quantum computing. Nuclear spins are superb quantum memories due to their long coherence times but are difficult to be read out in single shot due to their weak interaction with probes. Here we demonstrate single-shot readout of a weakly coupled $^{13}$C nuclear spin, which is unresolvable in traditional protocols. We use dynamical decoupling… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.07944v1-abstract-full').style.display = 'inline'; document.getElementById('1612.07944v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1612.07944v1-abstract-full" style="display: none;"> Single-shot readout of qubits is required for scalable quantum computing. Nuclear spins are superb quantum memories due to their long coherence times but are difficult to be read out in single shot due to their weak interaction with probes. Here we demonstrate single-shot readout of a weakly coupled $^{13}$C nuclear spin, which is unresolvable in traditional protocols. We use dynamical decoupling pulse sequences to selectively enhance the entanglement between the nuclear spin and a nitrogen-vacancy center electron spin, tuning the weak measurement of the nuclear spin to a strong, projective one. A nuclear spin coupled to the NV center with strength 330 kHz is read out in 200 ms with fidelity 95.5\%. This work provides a general protocol for single-shot readout of weakly coupled qubits and therefore largely extends the range of physical systems for scalable quantum computing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.07944v1-abstract-full').style.display = 'none'; document.getElementById('1612.07944v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">5 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 118, 150504 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1611.07015">arXiv:1611.07015</a> <span> [<a href="https://arxiv.org/pdf/1611.07015">pdf</a>, <a href="https://arxiv.org/ps/1611.07015">ps</a>, <a href="https://arxiv.org/format/1611.07015">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"> Properties of the Schr枚dinger Theory of Electrons in Electromagnetic Fields </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sahni%2C+V">Viraht Sahni</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiao-Yin 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="1611.07015v1-abstract-short" style="display: inline;"> The Schr枚dinger theory of electrons in an external electromagnetic field can be described from the perspective of the individual electron via the `Quantal Newtonian' laws (or differential virial theorems). These laws are in terms of `classical' fields whose sources are quantal expectations of Hermitian operators taken with respect to the wave function. The laws reveal the following physics: (a) In… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.07015v1-abstract-full').style.display = 'inline'; document.getElementById('1611.07015v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1611.07015v1-abstract-full" style="display: none;"> The Schr枚dinger theory of electrons in an external electromagnetic field can be described from the perspective of the individual electron via the `Quantal Newtonian' laws (or differential virial theorems). These laws are in terms of `classical' fields whose sources are quantal expectations of Hermitian operators taken with respect to the wave function. The laws reveal the following physics: (a) In addition to the external field, each electron experiences an internal field whose components are representative of a specific property of the system such as the correlations due to the Pauli exclusion principle and Coulomb repulsion, the electron density, kinetic effects, and an internal magnetic field component. (The response of the electron is described by the current density field.); (b) The scalar potential energy of an electron is the work done in a conservative field which is the sum of the internal and Lorentz fields. It is thus inherently related to the properties of the system. Its constituent property-related components are hence known. It is a known functional of the wave function; (c) As such the Hamiltonian is a functional of the wave function, thereby revealing the intrinsic self-consistent nature of the Schr枚dinger equation. This then provides a path for the determination of the exact wave function. (d) With the Schr枚dinger equation written in self-consistent form, the Hamiltonian now admits via the Lorentz field a new term that explicitly involves the external magnetic field. The new understandings are explicated for the stationary state case by application to a quantum dot in a magnetostatic field in both a ground and excited state. For the time-dependent case, the same states of the quantum dot in both a magnetostatic and a time-dependent electric field are considered. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.07015v1-abstract-full').style.display = 'none'; document.getElementById('1611.07015v1-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 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">16 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">MSC Class:</span> 81Q99 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1510.03514">arXiv:1510.03514</a> <span> [<a href="https://arxiv.org/pdf/1510.03514">pdf</a>, <a href="https://arxiv.org/ps/1510.03514">ps</a>, <a href="https://arxiv.org/format/1510.03514">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Experimental testing of entropic uncertainty relations with multiple measurements in pure diamond </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xing%2C+J">Jian Xing</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yu-Ran Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Shang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Chang%2C+Y">Yan-Chun Chang</a>, <a href="/search/quant-ph?searchtype=author&query=Yue%2C+J">Jie-Dong Yue</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+H">Heng Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu 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="1510.03514v1-abstract-short" style="display: inline;"> One unique feature of quantum mechanics is the Heisenberg uncertainty principle, which states that the outcomes of two incompatible measurements cannot simultaneously achieve arbitrary precision. In an information-theoretic context of quantum information, the uncertainty principle can be formulated as entropic uncertainty relations with two measurements for a quantum bit (qubit) in two-dimensional… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1510.03514v1-abstract-full').style.display = 'inline'; document.getElementById('1510.03514v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1510.03514v1-abstract-full" style="display: none;"> One unique feature of quantum mechanics is the Heisenberg uncertainty principle, which states that the outcomes of two incompatible measurements cannot simultaneously achieve arbitrary precision. In an information-theoretic context of quantum information, the uncertainty principle can be formulated as entropic uncertainty relations with two measurements for a quantum bit (qubit) in two-dimensional system. New entropic uncertainty relations are studied for a higher-dimensional quantum state with multiple measurements, the uncertainty bounds can be tighter than that expected from two measurements settings and cannot result from qubits system with or without a quantum memory. Here we report the first room-temperature experimental testing of the entropic uncertainty relations with three measurements in a natural three-dimensional solid-state system: the nitrogen-vacancy center in pure diamond. The experimental results confirm the entropic uncertainty relations for multiple measurements. Our result represents a more precise demonstrating of the fundamental uncertainty principle of quantum mechanics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1510.03514v1-abstract-full').style.display = 'none'; document.getElementById('1510.03514v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 October, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">8 pages, 5 figures, 2 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Scientific Reports 7, 2563 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1508.05960">arXiv:1508.05960</a> <span> [<a href="https://arxiv.org/pdf/1508.05960">pdf</a>, <a href="https://arxiv.org/ps/1508.05960">ps</a>, <a href="https://arxiv.org/format/1508.05960">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mathematical Physics">math-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Hohenberg-Kohn Theorems in Electrostatic and Uniform Magnetostatic Fields </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiao-Yin Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Sahni%2C+V">Viraht Sahni</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="1508.05960v1-abstract-short" style="display: inline;"> The Hohenberg-Kohn (HK) theorems of bijectivity between the external scalar potential and the gauge invariant nondegenerate ground state density, and the consequent Euler variational principle for the density, are proved for arbitrary electrostatic field and the constraint of fixed electron number. The HK theorems are generalized for spinless electrons to the added presence of an external uniform… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1508.05960v1-abstract-full').style.display = 'inline'; document.getElementById('1508.05960v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1508.05960v1-abstract-full" style="display: none;"> The Hohenberg-Kohn (HK) theorems of bijectivity between the external scalar potential and the gauge invariant nondegenerate ground state density, and the consequent Euler variational principle for the density, are proved for arbitrary electrostatic field and the constraint of fixed electron number. The HK theorems are generalized for spinless electrons to the added presence of an external uniform magnetostatic field by introducing the new constraint of fixed canonical orbital angular momentum. Thereby a bijective relationship between the external scalar and vector potentials, and the gauge invariant nondegenerate ground state density and physical current density, is proved. A corresponding Euler variational principle in terms of these densities is also developed. These theorems are further generalized to electrons with spin by imposing the added constraint of fixed canonical orbital and spin angular momentum. The proofs differ from the original HK proof, and explicitly account for the many-to-one relationship between the potentials and the nondegenerate ground state wave function. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1508.05960v1-abstract-full').style.display = 'none'; document.getElementById('1508.05960v1-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, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">16 pages; 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/1408.0480">arXiv:1408.0480</a> <span> [<a href="https://arxiv.org/pdf/1408.0480">pdf</a>, <a href="https://arxiv.org/ps/1408.0480">ps</a>, <a href="https://arxiv.org/format/1408.0480">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/ncomms7726">10.1038/ncomms7726 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Demonstration of Entanglement-Enhanced Phase Estimation in Solid </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yu-Ran Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chang%2C+Y">Yan-Chun Chang</a>, <a href="/search/quant-ph?searchtype=author&query=Yue%2C+J">Jie-Dong Yue</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+H">Heng Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu 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="1408.0480v2-abstract-short" style="display: inline;"> Precise parameter estimation plays a central role in science and technology. The statistical error in estimation can be decreased by repeating measurement, leading to that the resultant uncertainty of the estimated parameter is proportional to the square root of the number of repetitions in accordance with the central limit theorem. Quantum parameter estimation, an emerging field of quantum techno… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1408.0480v2-abstract-full').style.display = 'inline'; document.getElementById('1408.0480v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1408.0480v2-abstract-full" style="display: none;"> Precise parameter estimation plays a central role in science and technology. The statistical error in estimation can be decreased by repeating measurement, leading to that the resultant uncertainty of the estimated parameter is proportional to the square root of the number of repetitions in accordance with the central limit theorem. Quantum parameter estimation, an emerging field of quantum technology, aims to use quantum resources to yield higher statistical precision than classical approaches. Here, we report the first room-temperature implementation of entanglement-enhanced phase estimation in a solid-state system: the nitrogen-vacancy centre in pure diamond. We demonstrate a super-resolving phase measurement with two entangled qubits of different physical realizations: an nitrogen-vacancy centre electron spin and a proximal ${}^{13}$C nuclear spin. The experimental data shows clearly the uncertainty reduction when entanglement resource is used, confirming the theoretical expectation. Our results represent an elemental demonstration of enhancement of quantum metrology against classical procedure. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1408.0480v2-abstract-full').style.display = 'none'; document.getElementById('1408.0480v2-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 April, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 August, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">9 pages including the supplementary material, 6 figures in main text plus 3 figures in supplementary material</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 6, 6726 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1404.2519">arXiv:1404.2519</a> <span> [<a href="https://arxiv.org/pdf/1404.2519">pdf</a>, <a href="https://arxiv.org/format/1404.2519">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/10.1063/1.4885772">10.1063/1.4885772 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Band-selective shaped pulse for high fidelity quantum control in diamond </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chang%2C+Y">Yan-Chun Chang</a>, <a href="/search/quant-ph?searchtype=author&query=Xing%2C+J">Jian Xing</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+F">Fei-Hao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+Q">Qian-Qing Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Wu-Xia Li</a>, <a href="/search/quant-ph?searchtype=author&query=Gu%2C+C">Chang-Zhi Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Long%2C+G">Gui-Lu Long</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu 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="1404.2519v2-abstract-short" style="display: inline;"> High fidelity quantum control over qubits is of crucial importance for realistic quantum computing, and it turns to be more challenging when there are inevitable interactions among qubits. By employing a bandselective shaped pulse, we demonstrate a high fidelity flip over electron spin of nitrogen-vacancy (NV) centers in diamond. In contrast with traditional rectangular pulses, the shaped pulse ha… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1404.2519v2-abstract-full').style.display = 'inline'; document.getElementById('1404.2519v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1404.2519v2-abstract-full" style="display: none;"> High fidelity quantum control over qubits is of crucial importance for realistic quantum computing, and it turns to be more challenging when there are inevitable interactions among qubits. By employing a bandselective shaped pulse, we demonstrate a high fidelity flip over electron spin of nitrogen-vacancy (NV) centers in diamond. In contrast with traditional rectangular pulses, the shaped pulse has almost equal excitation effect among a sharply edged region (in frequency domain). So the three sub-levels of host $^{14}N$ nuclear spin can be flipped accurately at the same time, while the redundant flip of other sublevels (e. g. of a nearby $^{13}C$ nuclear spin ) is well suppressed. The shaped pulse can be applied to a large amount of quantum systems in which band-selective operation are required. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1404.2519v2-abstract-full').style.display = 'none'; document.getElementById('1404.2519v2-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 April, 2014; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 April, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">4 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Appl. Phys. Lett. 104 , 262403 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1311.1275">arXiv:1311.1275</a> <span> [<a href="https://arxiv.org/pdf/1311.1275">pdf</a>, <a href="https://arxiv.org/ps/1311.1275">ps</a>, <a href="https://arxiv.org/format/1311.1275">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"> A new optical field state as an output of diffusion channel when the input being number state </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Fan%2C+H">Hong-Yi Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Lou%2C+S">Sen-Yue Lou</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiao-Yin Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+L">Li-Yun Hu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1311.1275v1-abstract-short" style="display: inline;"> We theoretically propose a new optical field state which is named Laguerre-polynomial-weighted chaotic field. We show that such state can be implemented, i.e., when a number state enters into a diffusion channel, the output state is just this kind of states. We solve the master equation describing the diffusion process by using the summation method within ordered product of operators and the entan… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1311.1275v1-abstract-full').style.display = 'inline'; document.getElementById('1311.1275v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1311.1275v1-abstract-full" style="display: none;"> We theoretically propose a new optical field state which is named Laguerre-polynomial-weighted chaotic field. We show that such state can be implemented, i.e., when a number state enters into a diffusion channel, the output state is just this kind of states. We solve the master equation describing the diffusion process by using the summation method within ordered product of operators and the entangled state representaion. The solution manifestly shows how a pure state evolves into a mixed state. The physical difference between the diffusion and the amplitude damping is pointed out. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1311.1275v1-abstract-full').style.display = 'none'; document.getElementById('1311.1275v1-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 November, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2013. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1310.4120">arXiv:1310.4120</a> <span> [<a href="https://arxiv.org/pdf/1310.4120">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </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/ncomms3254">10.1038/ncomms3254 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Noise-resilient quantum evolution steered by dynamical decoupling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Po%2C+H+C">Hoi Chun Po</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+J">Jiangfeng Du</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Ren-Bao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu 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="1310.4120v1-abstract-short" style="display: inline;"> Realistic quantum computing is subjected to noise. A most important frontier in research of quantum computing is to implement noise-resilient quantum control over qubits. Dynamical decoupling can protect coherence of qubits. Here we demonstrate non-trivial quantum evolution steered by dynamical decoupling control, which automatically suppresses the noise effect. We designed and implemented a self-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1310.4120v1-abstract-full').style.display = 'inline'; document.getElementById('1310.4120v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1310.4120v1-abstract-full" style="display: none;"> Realistic quantum computing is subjected to noise. A most important frontier in research of quantum computing is to implement noise-resilient quantum control over qubits. Dynamical decoupling can protect coherence of qubits. Here we demonstrate non-trivial quantum evolution steered by dynamical decoupling control, which automatically suppresses the noise effect. We designed and implemented a self-protected controlled-NOT gate on the electron spin of a nitrogen-vacancy centre and a nearby carbon-13 nuclear spin in diamond at room temperature, by employing an engineered dynamical decoupling control on the electron spin. Final state fidelities of 0.91 and 0.88 were observed even with imperfect initial states. In the mean time, the qubit coherence time has been elongated by at least 30 folds. The design scheme does not require that the dynamical decoupling control commute with the qubit interaction and works for general systems. This work marks a step toward realistic quantum computing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1310.4120v1-abstract-full').style.display = 'none'; document.getElementById('1310.4120v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 October, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2013. </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">Originally submitted version. Revised version and Supplementary information can be download at http://www.nature.com/ncomms/2013/130805/ncomms3254/full/ncomms3254.html</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat. Commun. 4:2254 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1305.6424">arXiv:1305.6424</a> <span> [<a href="https://arxiv.org/pdf/1305.6424">pdf</a>, <a href="https://arxiv.org/format/1305.6424">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1039/c4nr02007c">10.1039/c4nr02007c <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Protection of center-spin coherence by dynamically polarizing nuclear spin core in diamond </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+Q">Qian-Qing Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Chang%2C+Y">Yan-Chun Chang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+D">Dong-Qi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Wu-Xia Li</a>, <a href="/search/quant-ph?searchtype=author&query=Gu%2C+C">Chang-Zhi Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Po%2C+H+C">Hoi Chun Po</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wen-Xian Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+N">Nan Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu 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="1305.6424v1-abstract-short" style="display: inline;"> We experimentally investigate the protection of electron spin coherence of nitrogen vacancy (NV) center in diamond by dynamical nuclear polarization. The electron spin decoherence of an NV center is caused by the magnetic ield fluctuation of the $^{13}$C nuclear spin bath, which contributes large thermal fluctuation to the center electron spin when it is in equilibrium state at room temperature. T… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1305.6424v1-abstract-full').style.display = 'inline'; document.getElementById('1305.6424v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1305.6424v1-abstract-full" style="display: none;"> We experimentally investigate the protection of electron spin coherence of nitrogen vacancy (NV) center in diamond by dynamical nuclear polarization. The electron spin decoherence of an NV center is caused by the magnetic ield fluctuation of the $^{13}$C nuclear spin bath, which contributes large thermal fluctuation to the center electron spin when it is in equilibrium state at room temperature. To address this issue, we continuously transfer the angular momentum from electron spin to nuclear spins, and pump the nuclear spin bath to a polarized state under Hartman-Hahn condition. The bath polarization effect is verified by the observation of prolongation of the electron spin coherence time ($T_2^*$). Optimal conditions for the dynamical nuclear polarization (DNP) process, including the pumping pulse duration and depolarization effect of laser pulses, are studied. Our experimental results provide strong support for quantum information processing and quantum simulation using polarized nuclear spin bath in solid state systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1305.6424v1-abstract-full').style.display = 'none'; document.getElementById('1305.6424v1-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 May, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2013. </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">4 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/1209.2901">arXiv:1209.2901</a> <span> [<a href="https://arxiv.org/pdf/1209.2901">pdf</a>, <a href="https://arxiv.org/ps/1209.2901">ps</a>, <a href="https://arxiv.org/format/1209.2901">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"> State-independent experimental test of quantum contextuality in solid state system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Chang%2C+Y">Yan-Chun Chang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+H">Heng Fan</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="1209.2901v2-abstract-short" style="display: inline;"> Quantum mechanics implies that not all physical properties can be simultaneously well defined, such as the momentum and position due to Heisenberg uncertainty principle. Some alternative theories have been explored, notably the non-contextual hidden variable theories in which the properties of a system have pre-defined values which are independent of the measurement contextual. However, the Kochen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1209.2901v2-abstract-full').style.display = 'inline'; document.getElementById('1209.2901v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1209.2901v2-abstract-full" style="display: none;"> Quantum mechanics implies that not all physical properties can be simultaneously well defined, such as the momentum and position due to Heisenberg uncertainty principle. Some alternative theories have been explored, notably the non-contextual hidden variable theories in which the properties of a system have pre-defined values which are independent of the measurement contextual. However, the Kochen-Specker theorem showed that such non-contextual hidden variable theories are in conflict with quantum mechanics. Recently, a state-independent inequality satisfied by non-contextual hidden variable theories and violated by quantum mechanics is proposed in the simplest three-state system (a qutrit) by the least 13 projection measurement rays. Here, we report an experimental demonstration of the violation of this inequality. This provides a state-independent experimental test of quantum contextuality, for the first time in solid state system, by a natural qutrit of nitrogen-vacancy center in diamond at room temperature. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1209.2901v2-abstract-full').style.display = 'none'; document.getElementById('1209.2901v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 September, 2012; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 September, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2012. </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, 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/1110.0331">arXiv:1110.0331</a> <span> [<a href="https://arxiv.org/pdf/1110.0331">pdf</a>, <a href="https://arxiv.org/format/1110.0331">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Controllable effects of quantum fluctuations on spin free-induction decay at room temperature </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+D">Dong-Qi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+Z">Zhan-Feng Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+N">Nan Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Ren-Bao Liu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1110.0331v1-abstract-short" style="display: inline;"> Fluctuations of local fields cause decoherence of quantum objects. It is generally believed that at high temperatures, thermal noises are much stronger than quantum fluctuations unless the thermal effects are suppressed by certain techniques such as spin echo. Here we report the discovery of strong quantum-fluctuation effects of nuclear spin baths on free-induction decay of single electron spins i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1110.0331v1-abstract-full').style.display = 'inline'; document.getElementById('1110.0331v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1110.0331v1-abstract-full" style="display: none;"> Fluctuations of local fields cause decoherence of quantum objects. It is generally believed that at high temperatures, thermal noises are much stronger than quantum fluctuations unless the thermal effects are suppressed by certain techniques such as spin echo. Here we report the discovery of strong quantum-fluctuation effects of nuclear spin baths on free-induction decay of single electron spins in solids at room temperature. We find that the competition between the quantum and thermal fluctuations is controllable by an external magnetic field. These findings are based on Ramsey interference measurement of single nitrogen-vacancy center spins in diamond and numerical simulation of the decoherence, which are in excellent agreement. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1110.0331v1-abstract-full').style.display = 'none'; document.getElementById('1110.0331v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 October, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2011. </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">4 pages 4 figures, experiment & theory</span> </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" 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