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quantum Microwave Parametric Interferometer

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Physical Review Applied 2023年第2期20卷 024049-024049页

作者： F. Kronowetter F. Fesquet M. Renger K. Honasoge Y. Nojiri K. Inomata Y. Nakamura A. Marx R. Gross K.G. Fedorov Walther-Meißner-Institut Bayerische Akademie der Wissenschaften Garching 85748 Germany School of Natural Sciences Technische Universität München Garching 85748 Germany Rohde & Schwarz GmbH & Co. KG Munich 81671 Germany RIKEN Center for Quantum Computing (RQC) Wako Saitama 351-0198 Japan National Institute of Advanced Industrial Science and Technology 1-1-1 Umezono Tsukuba Ibaraki 305-8563 Japan Department of Applied Physics Graduate School of Engineering The University of Tokyo Bunkyo-ku Tokyo 113-8656 Japan Munich Center for Quantum Science and Technology (MCQST) Munich 80799 Germany

Classical interferometers are indispensable tools for the precise determination of various physical quantities. Their accuracy is bound by the standard quantum limit. This limit can be overcome by using quantum states or nonlinear quantum elements. Here, we present the experimental study of a nonlinear Josephson interferometer operating in the microwave regime. Our quantum microwave parametric interferometer (QUMPI) is based on superconducting flux-driven Josephson parametric amplifiers combined with linear microwave elements. We perform a systematic analysis of the implemented QUMPI. We find that its interferometric power exceeds the shot-noise limit and observe sub-Poissonian photon statistics in the output modes. Furthermore, we identify a low-gain operation regime of the QUMPI that is essential for optimal quantum measurements in quantum illumination protocols.

关键词： Nonlinear optics Optoelectronics quantum metrology Superconducting quantum optics Josephson junctions Optical parametric oscillators & amplifiers Microwave techniques Optical interferometry

Generation of Highly Pure Single-Photon State at Telecommunication Wavelength

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arXiv 2022年

作者： Kawasaki, Akito Takase, Kan Nomura, Takefumi Miki, Sigehito Terai, Hirotaka Yabuno, Masahiro China, Fumihiro Asavanant, Warit Endo, Mamoru Yoshikawa, Jun-Ichi Furusawa, Akira Department of Applied Physics School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan Advanced ICT Research Institute National Institute of Information and Communications Technology 588-2 Iwaoka Nishi-ku Hyogo Kobe651-2492 Japan Graduate School of Engineering Kobe University 1-1 Rokkodai-cho Nada-ku Hyogo Kobe657-0013 Japan Optical Quantum Computing Research Team RIKEN center for Quantum Computing 2-1 Hirosawa Saitama Wako351-0198 Japan

Telecommunication wavelength with well-developed optical communication technologies and low losses in the waveguide are advantageous for quantum applications. However, an experimental generation of non-classical states called non-Gaussian states at the telecommunication wavelength is still underdeveloped. Here, we generate highly-pure-single-photon states, one of the most primitive non-Gaussian states, by using a heralding scheme with an optical parametric oscillator and a superconducting nano-strip photon detector. The Wigner negativity, the indicator of non-classicality, of the generated single photon state is -0.228 ± 0.004, corresponded to 85.1 ± 0.7% of single photon and the best record of the minimum value at all wavelengths. The quantum-optics-technology we establish can be easily applied to the generation of various types of quantum states, opening up the possibility of continuous-variable-quantum-information processing at the telecommunication wavelength. Copyright © 2022, The Authors. All rights reserved.

关键词： quantum optics

Heralded nonlocal quantum gates for distributed quantum computation in a decoherence-free subspace

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arXiv 2023年

作者： Su, Wanhua Qin, Wei Miranowicz, Adam Li, Tao Nori, Franco MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing School of Physics Nanjing University of Science and Technology Nanjing210094 China Center for Joint Quantum Studies Department of Physics School of Science Tianjin University Tianjin300350 China Theoretical Quantum Physics Laboratory Cluster for Pioneering Research RIKEN Wakoshi Saitama351-0198 Japan Institute of Spintronics and Quantum Information Faculty of Physics and Astronomy Adam Mickiewicz University PoznanPL-61-614 Poland Engineering Research Center of Semiconductor Device Optoelectronic Hybrid Integration in Jiangsu Province Nanjing210094 China Quantum Information Physics Theory Research Team Quantum Computing Center RIKEN Saitama Wako-shi351-0198 Japan Physics Department The University of Michigan Ann ArborMI48109-1040 United States

We propose a heralded protocol for implementing nontrivial quantum gates on two stationary qubits coupled to spatially separated cavities. By dynamically controlling the evolution of the composite system, nonlocal two-qubit quantum (e.g., CPHASE and CNOT) gates can be achieved without real excitations of either cavity modes or atoms. The success of our protocol is conditioned on projecting an auxiliary atom onto a postselected state, which simultaneously removes various detrimental effects of dissipation on the gate fidelity. In principle, the success probability of the gate can approach unity as the single-atom cooperativity becomes sufficiently large. Furthermore, we show its application for implementing single- and two-qubit gates within a decoherence-free subspace that is immune to a collective dephasing noise. This faithful, heralded, and nonlocal protocol could, therefore, be useful for distributed quantum computation and scalable quantum networks. © 2023, CC BY.

关键词： Qubits

Factoring integers with sublinear resources on a superconducting quantum processor

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arXiv 2022年

作者： Yan, Bao Tan, Ziqi Wei, Shijie Jiang, Haocong Wang, Weilong Wang, Hong Luo, Lan Duan, Qianheng Liu, Yiting Shi, Wenhao Fei, Yangyang Meng, Xiangdong Han, Yu Shan, Zheng Chen, Jiachen Zhu, Xuhao Zhang, Chuanyu Jin, Feitong Li, Hekang Song, Chao Wang, Zhen Ma, Zhi Wang, H. Long, Gui-Lu State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou450001 China State Key Laboratory of Low-Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China School of Physics ZJU-Hangzhou Global Scientific and Technological Innovation Center Interdisciplinary Center for Quantum Information Zhejiang Province Key Laboratory of Quantum Technology and Device Zhejiang University Hangzhou310000 China Beijing Academy of Quantum Information Sciences Beijing100193 China Institute of Information Technology Information Engineering University Zhengzhou450001 China Beijing National Research Center for Information Science and Technology School of Information Tsinghua University Beijing100084 China Frontier Science Center for Quantum Information Beijing100084 China

Shor’s algorithm has seriously challenged information security based on public key cryptosystems. However, to break the widely used RSA-2048 scheme, one needs millions of physical qubits, which is far beyond current technical capabilities. Here, we report a universal quantum algorithm for integer factorization by combining the classical lattice reduction with a quantum approximate optimization algorithm (QAOA). The number of qubits required is O(logN/loglogN), which is sublinear in the bit length of the integer N, making it the most qubit-saving factorization algorithm to date. We demonstrate the algorithm experimentally by factoring integers up to 48 bits with 10 superconducting qubits, the largest integer factored on a quantum device. We estimate that a quantum circuit with 372 physical qubits and a depth of thousands is necessary to challenge RSA-2048 using our algorithm. Our study shows great promise in expediting the application of current noisy quantum computers, and paves the way to factor large integers of realistic cryptographic significance. © 2022, CC BY-NC-ND.

关键词： Qubits

Topological quantum Batteries

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Physical Review Letters 2025年第18期134卷 180401-180401页

作者： Zhi-Guang Lu Guoqing Tian Xin-You Lü Cheng Shang School of Physics and Institute for Quantum Science and Engineering Huazhong University of Science and Technology and Wuhan Institute of Quantum Technology Wuhan 430074 China Department of Physics The University of Tokyo 5-1-5 Kashiwanoha Kashiwa Chiba 277-8574 Japan Analytical Quantum Complexity RIKEN Hakubi Research Team RIKEN Center for Quantum Computing (RQC) 2-1 Hirosawa Wako Saitama 351-0198 Japan

We propose an innovative design for quantum batteries (QBs) that involves coupling two-level systems to a topological photonic waveguide. Employing the resolvent method, we analytically explore the thermodynamic performance of QBs. First, we demonstrate that in the long-time limit, only bound states significantly contribute to the stored energy of QBs. We observe that near-perfect energy transfer can occur in the topologically nontrivial phase. Moreover, the maximum stored energy exhibits singular behavior at the phase boundaries, where the number of bound states undergoes a transition. Second, when a quantum charger and a quantum battery are coupled at the same sublattice within a unit cell, the ergotropy becomes immune to dissipation at that location, facilitated by a dark state and a topologically robust dressed bound state. Third, we show that as dissipation intensifies along with the emergence of the quantum Zeno effect, the charging power of QBs experiences a temporary boost. Our findings offer valuable guidance for improving quantum battery performance in realistic conditions through structured reservoir engineering.

关键词： Electric losses

Spinfoam on a Lefschetz thimble: Markov chain Monte Carlo computation of a Lorentzian spinfoam propagator

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Physical Review D 2021年第8期103卷 084026-084026页

作者： Muxin Han Zichang Huang Hongguang Liu Dongxue Qu Yidun Wan State Key Laboratory of Surface Physics Fudan University Shanghai 200433 China Department of Physics Center for Field Theory and Particle Physics Institute for Nanoelectronic devices and Quantum computing Fudan University Shanghai 200433 China and Department of Physics and Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 China

We compute numerically the Lorentzian Engle-Pereira-Rovelli-Livine spinfoam propagator on a 4-simplex, by adapting the Lefschetz thimble and Markov chain Monte-Carlo methods to oscillatory spinfoam integrals. Our method can compute any spinfoam observables at relatively large spins. We obtain the numerical results of the propagators at different spins and demonstrate their consistency with the expected spinfoam semiclassical behavior in the large spin limit. Our results exhibit significant quantum corrections at smaller spins. Our method is reliable and thus can be employed to discover the semiclassical and quantum behaviors of the spinfoam model.

关键词： Loop quantum gravity

Tuning atom-field interaction via phase shaping

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arXiv 2023年

作者： Cheng, Y.-T. Chien, C.-H. Hsieh, K.-M. Huang, Y.-H. Wen, P.Y. Lin, W.-J. Lu, Y. Aziz, F. Lee, C.-P. Lin, K.-T. Chen, C.-Y. Chen, J.C. Chuu, C.-S. Kockum, A.F. Lin, G.-D. Lin, Y.-H. Hoi, I.-C. Department of Physics National Tsing Hua University Hsinchu30013 Taiwan Department of Physics National Chung Cheng University Chiayi621301 Taiwan Chalmers University of Technology GothenburgSE-412 96 Sweden Department of Physics Center for Quantum Science and Engineering National Taiwan University Taipei10617 Taiwan Physics Division National Center for Theoretical Sciences Taipei10617 Taiwan Center for Quantum Technology National Tsing Hua University Hsinchu30013 Taiwan Trapped-Ion Quantum Computing Laboratory Hon Hai Research Institute Taipei11492 Taiwan Department of Physics City University of Hong Kong Tat Chee Avenue Kowloon Hong Kong

A coherent electromagnetic field can be described by its amplitude, frequency, and phase. All these properties can influence the interaction between the field and an atom. Here we demonstrate the phase shaping of microwaves that are scattered by a superconducting artificial atom coupled to the end of a semi-infinite 1D transmission line. In particular, we input a weak exponentially rising pulse with phase modulation to a transmon qubit. We observe that field-atom interaction can be tuned from nearly full interaction (interaction efficiency, i.e., amount of the field energy interacting with the atom, of 94.5 %) to effectively no interaction (interaction efficiency 3.5 %). Copyright © 2023, The Authors. All rights reserved.

关键词： Atoms

Phase-engineered bosonic quantum codes

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Physical Review A 2021年第6期103卷 062427-062427页

作者： Linshu Li Dylan J. Young Victor V. Albert Kyungjoo Noh Chang-Ling Zou Liang Jiang Yale Quantum Institute Department of Applied Physics and Department of Physics Yale University New Haven Connecticut 06511 USA JILA NIST and Department of Physics University of Colorado 440 UCB Boulder Colorado 80309 USA Institute for Quantum Information and Matter and Walter Burke Institute for Theoretical Physics California Institute of Technology Pasadena California 91125 USA AWS Center for Quantum Computing Pasadena California 91125 USA Key Laboratory of Quantum Information University of Science and Technology of China Hefei Anhui 230026 China Pritzker School of Molecular Engineering University of Chicago 5640 South Ellis Avenue Chicago Illinois 60637 USA

Continuous-variable systems protected by bosonic quantum codes have emerged as a promising platform for quantum information. To date, the design of code words has centered on optimizing the state occupation in the relevant basis to generate the distance needed for error correction. Here, we show tuning the phase degree of freedom in the design of code words can affect, and potentially enhance, the protection against Markovian errors that involve excitation exchange with the environment. As illustrations, we first consider phase engineering bosonic codes with uniform spacing in the Fock basis that correct excitation loss with a Kerr unitary and show that these modified codes feature destructive interference between error code words and, with an adapted “two-level” recovery, the error protection is significantly enhanced. We then study protection against energy decay with the presence of mode nonlinearities and analyze the role of phase for optimal code designs. We extend the principle of phase engineering to bosonic codes defined in other bases and multiqubit codes, demonstrating its broad applicability in quantum error correction.

关键词： quantum error correction quantum information processing with continuous variables

Digital noise spectroscopy with a quantum sensor

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arXiv 2022年

作者： Wang, Guoqing Zhu, Yuan Li, Boning Li, Changhao Viola, Lorenza Cooper, Alexandre Cappellaro, Paola Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Nuclear Science and Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics and Astronomy Dartmouth College 6127 Wilder Laboratory HanoverNH03755 United States Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada

We introduce and experimentally demonstrate a quantum sensing protocol to sample and reconstruct the auto-correlation of a noise process using a single-qubit sensor under digital control modulation. This Walsh noise spectroscopy method exploits simple sequences of spin-flip pulses to generate a complete basis of digital filters that directly sample the power spectrum of the target noise in the sequency domain - from which the auto-correlation function in the time domain, as well as the power spectrum in the frequency domain, can be reconstructed using linear transformations. Our method, which can also be seen as an implementation of frame-based noise spectroscopy, solves the fundamental difficulty in sampling continuous functions with digital filters by introducing a transformation that relates the arithmetic and logical time domains. In comparison to standard, frequency-based dynamical-decoupling noise spectroscopy protocols, the accuracy of our method is only limited by the sampling and discretization in the time space and can be easily improved, even under limited evolution time due to decoherence and hardware limitations. Finally, we experimentally reconstruct the auto-correlation function of the effective magnetic field produced by the nuclear-spin bath on the electronic spin of a single nitrogen-vacancy center in diamond, discuss practical limitations of the method, and avenues for further improving the reconstruction accuracy. Copyright © 2022, The Authors. All rights reserved.

关键词： Digital filters