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Measuring a dynamical topological order parameter in quantum walks

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Light(Science & Applications) 2020年第1期9卷 1932-1942页

作者： Xiao-Ye Xu Qin-Qin Wang Markus Heyl Jan Carl Budich Wei-Wei Pan Zhe Chen Munsif Jan Kai Sun Jin-Shi Xu Yong-Jian Han Chuan-Feng Li guang-can guo CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China Max-Planck-Institut fur Physik komplexer Systeme Nöthnitzer Straße 38D-01187 DresdenGermany Institute of Theoretical Physics Technische Universitat Dresden01062 DresdenGermany

Quantum processes of inherent dynamical nature,such as quantum walks,defy a description in terms of an equilibrium statistical physics *** now,identifying the general principles behind the underlying unitary quantum dynamics has remained a key ***,we show and experimentally observe that split-step quantum walks admit a characterization in terms of a dynamical topological order parameter(DTOP).This integer-quantized DTOP measures,at a given time,the winding of the geometric phase accumulated by the wavefunction during a quantum *** observe distinct dynamical regimes in our experimentally realized quantum walks,and each regime can be attributed to a qualitatively different temporal behavior of the *** identifying an equivalent manybody problem,we reveal an intriguing connection between the nonanalytic changes of the DTOP in quantum walks and the occurrence of dynamical quantum phase transitions.

关键词： quantum dynamical topological

Room-temperature coherent manipulation of single-spin qubits in silicon carbide with a high readout contrast

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National Science Review 2022年第5期9卷 89-98页

作者： Qiang Li Jun-Feng Wang Fei-Fei Yan Ji-Yang Zhou Han-Feng Wang He Liu Li-Ping guo Xiong Zhou Adam Gali Zheng-Hao Liu Zu-Qing Wang Kai Sun guo-Ping guo Jian-Shun Tang Hao Li Li-Xing You Jin-Shi Xu Chuan-Feng Li guang-can guo CAS Key Laboratory of Quantum Information University of Science and Technology of China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education and School of Physics and Technology Wuhan University Department of Atomic Physics Budapest University of Technology and Economics Wigner Research Centre for Physics State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences(CAS)

Spin defects in silicon carbide(SiC) with mature wafer-scale fabrication and micro/nano-processing technologies have recently drawn considerable *** room-temperature single-spin manipulation of colour centres in SiC has been demonstrated,the typically detected contrast is less than 2%,and the photon count rate is also ***,we present the coherent manipulation of single divacancy spins in 4 H-SiC with a high readout contrast(-30%) and a high photon count rate(150 kilo counts per second)under ambient conditions,which are competitive with the nitrogen-vacancy centres in *** between a single defect spin and a nearby nuclear spin is also *** further provide a theoretical explanation for the high readout contrast by analysing the defect levels and decay *** the high readout contrast is of utmost importance in many applications of quantum technologies,this work might open a new territory for SiC-based quantum devices with many advanced properties of the host material.

关键词： silicon carbide single divacancy defects spin coherent control high readout contrast bright photon emission

Interaction of Quantum Optics and Surface Plasmon

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量子光学学报 2006年第B8期12卷 64-64页

作者： guo-Ping guo guang-can guo Key Laboratory of Quantum Information University of Science and Technology of China Chinese Academy of SciencesHefei Anhui 230026 China

Experimental realization of nonadiabatic holonomic single‐qubit quantum gates with two dark paths in a trapped ion

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Fundamental Research 2022年第5期2卷 661-666页

作者： Ming-Zhong Ai Sai Li Ran He Zheng-Yuan Xue Jin-Ming Cui Yun-Feng Huang Chuan-Feng Li guang-can guo CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China CAS Center For Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials and School of Physics and Telecommunication EngineeringSouth China Normal UniversityGuangzhou 510006China guangdong-Hong Kong Joint Laboratory of Quantum Matter and Frontier Research Institute for PhysicsSouth China Normal UniversityGuangzhou 510006China

For circuit-based quantum computation,experimental implementation of a universal set of quantum logic gates with high-fidelity and strong robustness is essential and *** gates induced by geometric phases,which depend only on global properties of the evolution paths,have built-in noise-resilience ***,we propose and experimentally demonstrate nonadiabatic holonomic single-qubit quantum gates on two dark paths in a trapped ^(171)γδ^(+)ion based on four-level systems with resonant *** confirm the implementation with measured gate fidelity through both quantum process tomography and randomized benchmarking ***,we find that nontrivial holonomic two-qubit quantum gates can also be realized within current experimental *** with previous implementations,our experiments share both the advantages of fast nonadiabatic evolution and robustness against systematic ***,our experiments confirm a promising method for fast and robust holonomic quantum computation.

关键词： Geometric phase Quantum computation Nonadiabatic evolution Noise robustness Ion trap

Silicon carbide based quantum networking

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Fundamental Research 2021年第2期1卷 220-222页

作者： Jin-Shi Xu Chuan-Feng Li guang-can guo CAS Key Laboratory of Quanoum Informaion Untversty of Science and Technology of ChinaHefelAnhui 230026People's Republic of China CAS Center for Exellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefeil Anhui 230026People's Republic ofChina

*** defects in silicon carbide Solid-state qubits are critical for scalable quantum information *** of the most studied optically addressable solid-state spin systems is the negatively charged nitrogen-vacancy(NV)center in di-amond,which has been widely used in quantum communication and quantum ***,the visible wavelength emission of NV cen-ters in diamond causes a large loss in fiber transmission and has shallow penetration depth in biological ***,there is still a lack of mature growing and nanofabrication methods for diamond.

关键词： quantum visible vacancy

Differentially private SGD with random features

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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 1-23页

作者： WANG Yi-guang guo Zheng-chu Polytechnic Institute of Zhejiang University Zhejiang UniversityHangzhou 310015China School of Mathematical Sciences Zhejiang UniversityHangzhou 310058China

In the realm of large-scale machine learning,it is crucial to explore methods for reducing computational complexity and memory demands while maintaining generalization ***,since the collected data may contain some sensitive information,it is also of great significance to study privacy-preserving machine learning *** paper focuses on the performance of the differentially private stochastic gradient descent(SGD)algorithm based on random *** begin,the algorithm maps the original data into a lowdimensional space,thereby avoiding the traditional kernel method for large-scale data storage ***,the algorithm iteratively optimizes parameters using the stochastic gradient descent ***,the output perturbation mechanism is employed to introduce random noise,ensuring algorithmic *** prove that the proposed algorithm satisfies the differential privacy while achieving fast convergence rates under some mild conditions.

关键词： learning theory differential privacy stochastic gradient descent random features reproducing kernel Hilbert spaces

Bayesian Optimization for Wavefront Sensing and Error Correction

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Chinese Physics Letters 2021年第6期38卷 40-44页

作者： Zhong-Hua Qian Zi-Han Ding Ming-Zhong Ai Yong-Xiang Zheng Jin-Ming Cui Yun-Feng Huang Chuan-Feng Li guang-can guo CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China CAS Center For Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China Department of Electrical and Computer Engineering Princeton UniversityPrincetonNew Jersey 08544USA

Algorithms for wavefront sensing and error correction from intensity attract great concern in many *** we propose Bayesian optimization to retrieve phase and demonstrate its performance in simulation and *** small aberration,this method demonstrates a convergence process with high accuracy of phase sensing,which is also verified *** large aberration,Bayesian optimization is shown to be insensitive to the initial phase while maintaining high *** approach’s merits of high accuracy and robustness make it promising in being applied in optical systems with static aberration such as AMO experiments,optical testing shops,and electron or optical microscopes.

关键词： optical optimization phase

A transportable long-lived coherent memory for light pulses

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Science Bulletin 2022年第23期67卷 2402-2405,M0003页

作者： Zong-Quan Zhou Duo-Lun Chen Ming Jin Liang Zheng You-Zhi Ma Tao Tu Alban Ferrier Philippe Goldner Chuan-Feng Li guang-can guo CAS key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China Chimie ParisTech PSL UniversityCNRSInstitut de Recherche de Chimie ParisParis 75005France Faculte des Sciences et Ingenierie Sorbonne UniversiteUFR933Paris 75005France

Optical memories can be categorized into three regimes,including the optical data storage that use light as a tool to store classical bit values[1,2],coherent memories for light which preserve the amplitude and the phase information of input optical pulses[3,4]and optical quantum memories that specifically work for quantum light field[5,6].Recently,Bland-Hawthorn et al.[7]proposed to construct long-baseline optical telescopes based on transportable optical memories.

关键词：存储器光存储相干光光信息处理轨道角动量量子光学基础物理光学干涉

Spectrally multiplexed and bright entangled photon pairs in a lithium niobate microresonator

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Science China(Physics,Mechanics & Astronomy) 2022年第9期65卷 3-9页

作者： Bo-Yu Xu Li-Kun Chen Jin-Tian Lin Lan-Tian Feng Rui Niu Zhi-Yuan Zhou Ren-Hong Gao Chun-Hua Dong guang-can guo Qi-Huang Gong Ya Cheng Yun-Feng Xiao Xi-Feng Ren CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics School of PhysicsPeking UniversityBeijing 100871China State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science Shanghai Institute of Optics and Fine Mechanics(SIOM)Chinese Academy of Sciences(CAS)Shanghai 201800China CAS Synergetic Innovation Center of Quantum Information&Quantum Physics University of Science and Technology of ChinaHefei 230026China State Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200062China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

On-chip bright quantum sources with multiplexing ability are extremely high in demand for integrated quantum networks with unprecedented scalability and ***,we demonstrate a bright and broadband biphoton quantum source with spectral multiplexing generated in a lithium niobate microresonator *** introducing the conventional domain poling,the on-chip microdisk produces photon pairs covering a broad bandwidth promised by natural phase matching in spontaneous parametric down ***,the multiplexed photon pairs are characterized by 30 nm bandwidth limited by the filtering system,providing over 40 multiplexing channels with a 0.8 nm channel ***,the generation rate reaches 5.13 MHz/μW with a coincidence-to-accidental ratio up to 804,and the quantum source manifests a high purity with a heralded single photon correlation g^((2))_(H)(0)=0.0098±***,the energy-time entanglement is demonstrated with an excellent interference visibility of 96.5%±2%.Such a quantum source at the telecommunication band paves the way for high-dimensional entanglement and future integrated quantum information systems.

关键词： quantum entangled source spectral multiplexing lithium niobate on insulator microresonator