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Observation of dark edge states in parity-time-symmetric quantum dynamics

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National Science Review 2023年第8期10卷 156-165页

作者： Peng Xue Xingze Qiu Kunkun Wang Barry C. Sanders Wei Yi Beijing Computational Science Research Center Key Laboratory of quantum information University of Science and Technology of China Chinese Academy of Sciences synergetic innovation Center in quantum information and quantum physics University of Science and Technology of China Chinese Academy of Sciences 4. School of Physics and Optoelectronic Engineering Anhui University Shanghai Branch National Laboratory for Physical Sciences at MicroscaleUniversity of Science and Technology of China Institute for quantum Science and Technology University of Calgary Program in quantum information Science Canadian Institute for Advanced Research

Topological edge states arise in non-Hermitian parity-time(PT)-symmetric systems, and manifest themselves as bright or dark edge states, depending on the imaginary components of their eigenenergies. As the spatial probabilities of dark edge states are suppressed during the non-unitary dynamics, it is a challenge to observe them experimentally. Here we report the experimental detection of dark edge states in photonic quantum walks with spontaneously broken PT symmetry, thus providing a complete description of the topological phenomena therein. We experimentally confirm that the global Berry phase in PT-symmetric quantum-walk dynamics unambiguously defines topological invariants of the system in both the PT-symmetry-unbroken and-broken regimes. Our results establish a unified framework for characterizing topology in PT-symmetric quantum-walk dynamics, and provide a useful method to observe topological phenomena in PT-symmetric non-Hermitian systems in general.

关键词： parity-time symmetry photonic quantum walks dark edge states topological invariants

Experimental exploration of five-qubit quantum error-correcting code with superconducting qubits

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National Science Review 2022年第1期9卷 100-106页

作者： Ming Gong Xiao Yuan Shiyu Wang Yulin Wu Youwei Zhao Chen Zha Shaowei Li Zhen Zhang Qi Zhao Yunchao Liu Futian Liang Jin Lin Yu Xu Hui Deng Hao Rong He Lu Simon C.Benjamin Cheng-Zhi Peng Xiongfeng Ma Yu-Ao Chen Xiaobo Zhu Jian-Wei Pan Hefei National Laboratory for Physical sciences at the Microscale and Department of Modern physics University of Science and Technology of China Shanghai Branch CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics University of Science and Technology of China Shanghai Research Center for quantum sciences Center for quantum information Institute for Interdisciplinary Information Sciences Tsinghua University Department of Materials University of Oxford

quantum error correction is an essential ingredient for universal quantum computing.D espite tremendous experimental efforts in the study of quantum error correction,to date,there has been no demonstration in the realis ation of universal quantum error-correcting code,with the subsequent verification of all key features including the identification of an arbitrary physical error,the capability for transversal manipulation of the logical state and state *** address this challenge,we experimentally realise the [5,1,3]code,the so-called smallest perfect code that permits corrections of generic single-qubit *** the experiment,having optimised the encoding circuit,we employ an array of superconducting qubits to realise the [5,1,3] code for several typical logical states including the magic state,an indispensable resource for realising non-Clifford *** encoded states are prepared with an average fidelity of 57.1(3)% while with a high fidelity of 98.6(1)% in the code ***,the arbitrary single-qubit errors introduced manually are identified by measuring the *** further implement logical Pauli operations with a fidelity of 97.2(2)% within the code ***,we realise the decoding circuit and recover the input state with an overall fidelity of 74.5(6)%,in total with 92 *** work demonstrates each key aspect of the [5,1,3] code and verifies the viability of experimental realisation of quantum error-correcting codes with superconducting qubits.

关键词： quantum error-correcting code superconducting qubit five-qubit code error detection logical operation

Interaction-induced particle-hole symmetry breaking and fractional exclusion statistics

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National Science Review 2022年第12期9卷 204-210页

作者： Xibo Zhang Yang-Yang Chen Longxiang Liu Youjin Deng Xiwen Guan International Center for quantum Materials School of PhysicsPeking University Collaborative innovation Center of quantum Matter Beijing academy of quantum information sciences State Key Laboratory of Magnetic Resonance and Atomic and Molecular physics Wuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of Sciences Institute of Modern physics Northwest University chinese academy of sciences Center for excellence in quantum information and quantum physics University of Science and Technology of China Min Jiang Collaborative Center for Theoretical physics College of Physics and Electronic Information Engineering Minjiang University Department of Theoretical physics Research School of Physics and EngineeringAustralian National University

quantum statistics plays a fundamental role in the laws of *** fractional exclusion statistics(FES) generalizes the Pauli exclusion statistics,and can emerge in the properties of elementary particles and hole excitations of a quantum system consisting of conventional bosons or *** has a long history of intensive studies,but its simple realization in interacting physical systems is *** we report a simple non-mutual FES that depicts the particle-hole symmetry breaking in interacting Bose gases at a quantum critical *** show that the FES distribution directly comes from particle-hole symmetry *** on exact solutions,quantum Monte Carlo simulations and experiments,we find that,over a wide range of interaction strengths,the macroscopic physical properties of these gases are determined by non-interacting quasi-particles that obey non-mutual FES of the same form in one and two *** strongly interacting Bose gases reach full fermionization in one dimension,they exhibit incomplete fermionization in two *** results provide a generic connection between interaction-induced particle-hole symmetry breaking(depicted by FES) and macroscopic properties of many-body systems in arbitrary *** work lays the groundwork for using FES to explore quantum criticality and other novel many-body phenomena in strongly correlated quantum systems.

关键词： quantum statistics interaction particle-hole symmetry breaking fractional exclusion statistics strongly correlated quantum materials

Manipulating high-temperature superconductivity by oxygen doping in Bi2Sr2CaCu2O8+δ thin flakes

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National Science Review 2022年第10期9卷 112-119页

作者： Bin Lei Donghui Ma Shihao Liu Zeliang Sun Mengzhu Shi Weizhuang Zhuo Fanghang Yu Genda Gu Zhenyu Wang Xianhui Chen Key Laboratory of Strongly-Coupled quantum Matter physics Chinese Academy of Sciences and Department of Physics University of Science and Technology of China CAS Center for excellence in quantum information and quantum physics Department of Condensed Matter physics and Materials Science Brookhaven National Laboratory CAS Center for excellence in Superconducting Electronics (CENSE) Collaborative innovation Center of Advanced Microstructures Nanjing University

Harnessing the fascinating properties of correlated oxides requires precise control of their carrier *** to other methods,oxygen doping provides an effective and more direct way to tune the electronic properties of correlated *** several approaches,such as thermal annealing and oxygen migration,have been introduced to change the oxygen content,a continuous and reversible solution that can be integrated with modern electronic technology is much in ***,we report a novel ionic field-effect transistor using solid Gd-doped CeO2as the gate dielectric,which shows a remarkable carrier-density-tuning ability via electric-field-controlled oxygen concentration at room *** Bi2Sr2CaCu2O8+δ(Bi-2212) thin flakes,we achieve a reversible superconductor-insulator transition by driving oxygen ions in and out of the samples with electric fields,and map out the phase diagram all the way from the insulating regime to the over-doped superconducting regime by continuously changing the oxygen doping *** analysis indicates that the reversible superconductor-insulator transition for the Bi-2212 thin flakes follows the theoretical description of a two-dimensional quantum phase *** work provides a route for realizing electric-field control of phase transition in correlated ***,the configuration of this type of transistor makes heterostructure/interface engineering possible,thus having the potential to serve as the next-generation all-solid-state field-effect transistor.

关键词： high-temperature superconductivity oxygen doping electric field effect all-solid-state field effect transistor superconductor–insulator transition

Production of an ultracold mixture of ^(23)Na^(40)K and ^(40)K

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Science China(physics,Mechanics & Astronomy) 2022年第2期65卷 39-43页

作者： Xin-Yao Wang Zhen Su Jin Cao Huan Yang Bo Zhao Chun-Li Bai Jian-Wei Pan Beijing National Laboratory for Molecular sciences Key Laboratory of Molecular Nanostructure and NanotechnologyCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China Hefei National Laboratory for Physical sciences at the Microscale and Department of Modern physics University of Science and Technology of ChinaHefei 230026China Shanghai Branch CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum PhysicsUniversity of Science and Technology of ChinaShanghai 201315China A Shanghai Research Center for quantum sciences Shanghai 201315China University of chinese academy of sciences Beijing 100049China

We report on the production of an ultracold mixture of 2.8×10^(4)^(23)Na^(40)K molecules and 3.3×10^(5)^(40)K atoms at a temperature of about 250 n *** with previous studies,the number of atoms and molecules improved by a factor of about 2,and the temperature reduced by a factor of about *** improvements occur mainly because of the use of a crossed large-volume horizontal dipole trap to load the atoms from a cloverleaf-type magnetic trap,and a large-volume three-beam dipole trap to perform optical evaporative *** achieving the mode-matching loading,this method avoids evaporative cooling in a decompressed cloverleaf magnetic trap,which is sensitive to magnetic field *** characterize an atom-molecule Feshbach resonance using the ultracold atom-molecule *** enhancement of particle number and temperature significantly improves the signal-to-noise ratio,and enables us to refine the location and width of the Feshbach resonance.

关键词： ultracold molecule Bose-Fermi mixture Feshbach resonance

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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

Fabrication and characterization of ultra-low noise narrow and wide band Josephson parametric amplifiers

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chinese physics B 2017年第9期26卷 198-203页

作者：黄克强郭秋江宋超郑亚锐邓辉吴玉林金贻荣朱晓波郑东宁 Institute of physics and Beijing National Laboratory for Condensed Matter physics Chinese Academy of Sciences School of physics University of Chinese Academy of Sciences Department of physics Zhejiang University CAS centre for excellence and synergetic innovation centre in quantum information and quantum physics University of Science and Technology of China

We have fabricated two types of lumped-element Josephson parameter amplifiers（JPAs） by using a multilayer microfabrication process involving wet etching of Al films. The first type is a narrow band JPA which shows typical gain above14 dB in a bandwidth around 35 MHz. The second type is a wideband JPA which is coupled to an input 50Ω transmission line via an impedance transformer that changes the impedance from about 15 Ω on the non-linear resonator side to 50 Ωon the input transmission line side. The wideband JPA could operate in a 200 MHz range with a gain higher than 14 d *** amplifiers were used for superconducting qubit readout. The results showed that the signal to noise ratio and hence the readout fidelity were improved significantly.

关键词： Josephson parameter amplifier multilayer micro-fabrication qubit state readout

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Asymmetricalπback-donation of hetero-dicationic Mo^(4+)-Mo^(6+)pairs for enhanced electrochemical nitrogen reduction

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Nano Research 2022年第4期15卷 3010-3016页

作者： Hao Tan Qianqian Ji Chao Wang Hengli Duan Yuan Kong Yao Wang Sihua Feng Liyang Lv Fengchun Hu Wenhua Zhang Wangsheng Chu Zhihu Sun Wensheng Yan National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China Hefei National Laboratory for Physical sciences at the Microscale and Department of Chemical Physics and Synergetic Innovation Center of Quantum Information and Quantum PhysicsUniversity of Science and Technology of ChinaHefei 230029China

The breaking of nonpolar N≡N bond of dinitrogen is the biggest dilemma for electrocatalytic nitrogen reduction reaction(NRR)application,driving electron migration between catalysts and N≡N bond(termed“πback-donation”process)is crucial for attenuating interfacial energy barrier but still remains ***,using density functional theory calculations,we revealed that constructing a unique hetero-dicationic Mo^(4+)-Mo^(6+)pair could effectively activate N≡N bond with a lying-down chemisorption configuration by an asymmetrical“πback-donation”*** a proof-of-concept demonstration,we synthesized MoO_(2)@MoO_(3)heterostructure with double Mo sites(Mo^(4+)-Mo^(6+)),which are embedded in graphite,for electrochemical nitrogen ***,this hetero-dicationic Mo^(4+)-Mo^(6+)pair catalysts display more excellent catalytic performance with a high NH_(3)yield(60.9μg·h^(-1)·mg^(-1))and Faradic efficiency(23.8%)as NRR catalysts under ambient conditions than pristine MoO_(2)and MoO_(3).Operando characterizations using synchrotron-based spectroscopic techniques identified the emergence of a key^(*)N_(2)Hy intermediate on Mo sites during NRR,which indicates that the Mo sites are active sites and the NRR process tends to follow an associative *** novel type of hetero-dicationic catalyst has tremendous potential as a new class of transition metal-based catalysts with promising applications in electrocatalysis and catalysts for energy conversion and storage.

关键词： asymmetrical"πback-donation"process hetero-dicationic Mo^(4+)–Mo^(6+)pairs nitrogen reduction reaction operando experimental characterizations

Pressure tuning of the anomalous Hall effect in the kagome superconductor CsV_(3)Sb_(5)

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chinese physics B 2022年第1期31卷 31-36页

作者：喻芳航温茜凯桂智刚吴涛王震宇项子霁应剑俊陈仙辉 Hefei National Laboratory for Physical sciences at Microscale and Department of physics and CAS Key Laboratory of Strongly-coupled Quantum Matter PhysicsUniversity of Science and Technology of ChinaHefei 230026China CAS Center for excellence in quantum information and quantum physics Hefei 230026China Collaborative innovation Center of Advanced Microstructures Nanjing 210093China

Controlling the anomalous Hall effect(AHE)inspires potential applications of quantum materials in the next generation of *** recently discovered quasi-2D kagome superconductor CsV_(3)Sb_(5) exhibits large AHE accompanying with the charge-density-wave(CDW)order which provides us an ideal platform to study the interplay among nontrivial band topology,CDW,and unconventional ***,we systematically investigated the pressure effect of the AHE in CsV_(3)Sb_(5).Our high-pressure transport measurements confirm the concurrence of AHE and CDW in the compressed CsV_(3)Sb_(5).Remarkably,distinct from the negative AHE at ambient pressure,a positive anomalous Hall resistivity sets in below 35 K with pressure around 0.75 GPa,which can be attributed to the Fermi surface reconstruction and/or Fermi energy shift in the new CDW phase under *** work indicates that the anomalous Hall effect in CsV_(3)Sb_(5) is tunable and highly related to the band structure.

关键词： anomalous Hall effect(AHE) charge-density-wave(CDW) kagome superconductor pressure effect

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