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Chinese physics C 2016年第11期40卷 152-158页

作者：易晗吕黎明张钊程文静季伟黄彦张嫣李红洁崔银平林明王轶杰段利敏胡荣江肖志刚 Department of physics Tsinghua University Institute of Modern physics Chinese Academy of Sciences Collaborative Innovation center of quantum Matter

A Flash-ADC data acquisition （DAQ） system has been developed for the drift chamber array designed for the External-Target-Experiment at the Cooling Storage Ring at the Heavy Ion Research Facility, Lanzhou. The simplified readout electronics system has been developed using the Flash-ADC modules and the whole waveform in the sampling window is obtained, with which the time and energy information can be deduced with an offiine processing. A digital filter algorithm has been developed to discriminate the noise and the useful signal. With the digital filtering process, the signal to noise ratio （SNR） is increased and a better time and energy resolution can be obtained.

关键词： external target experiment multiwire drift chamber flash-ADC DAQ

Low-temperature growth of large-scale,single-crystalline graphene on Ir(111)

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Chinese physics B 2019年第5期28卷 11-15页

作者： Hui Guo Hui Chen Yande Que Qi Zheng Yu-Yang Zhang Li-Hong Bao Li Huang Ye-Liang Wang Shi-Xuan Du Hong-Jun Gao Institute of physics and University of Chinese Academy of sciences CAS center for Excellence in Topological quantum Computation University of Chinese Academy of Sciences

Iridium is a promising substrate for self-limiting growth of graphene. However, single-crystalline graphene can only be fabricated over 1120 K. The weak interaction between graphene and Ir makes it challenging to grow graphene with a single orientation at a relatively low temperature. Here, we report the growth of large-scale, single-crystalline graphene on Ir(111) substrate at a temperature as low as 800 K using an oxygen-etching assisted epitaxial growth method. We firstly grow polycrystalline graphene on Ir. The subsequent exposure of oxygen leads to etching of the misaligned *** growth cycle, in which the leftover aligned domain serves as a nucleation center, results in a large-scale and single-crystalline graphene layer on Ir(111). Low-energy electron diffraction, scanning tunneling microscopy, and Raman spectroscopy experiments confirm the successful growth of large-scale and single-crystalline graphene. In addition, the fabricated single-crystalline graphene is transferred onto a SiO_2/Si substrate. Transport measurements on the transferred graphene show a carrier mobility of about 3300 cm^2·V^(-1)·s^(-1). This work provides a way for the synthesis of large-scale,high-quality graphene on weak-coupled metal substrates.

关键词： graphene low-temperature growth single-crystalline Ir(111)

High-Chern-number and high-temperature quantum Hall effect without Landau levels

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National Science Review 2020年第8期7卷 1280-1287页

作者： Jun Ge Yanzhao Liu Jiaheng Li Hao Li Tianchuang Luo Yang Wu Yong Xu Jian Wang International center for quantum Materials School of Physics Peking University State Key Laboratory of Low Dimensional quantum physics Department of Physics Tsinghua University School of Materials Science and Engineering Tsinghua University Tsinghua-Foxconn Nanotechnology Research center and Department of physics Tsinghua University Department of Mechanical Engineering Tsinghua University Frontier Science center for quantum Information CAS center for Excellence in Topological quantum Computation University of Chinese Academy of Sciences

The quantum Hall effect（QHE） with quantized Hall resistance of h/νe;started the research on topological quantum states and laid the foundation of topology in physics. Since then, Haldane proposed the QHE without Landau levels, showing nonzero Chern number |C| = 1, which has been experimentally observed at relatively low temperatures. For emerging physics and low-power-consumption electronics, the key issues are how to increase the working temperature and realize high Chern numbers（C > 1）. Here, we report the experimental discovery of high-Chern-number QHE（C = 2） without Landau levels and C = 1 Chern insulator state displaying a nearly quantized Hall resistance plateau above the Néel temperature in MnBi;Te;devices. Our observations provide a new perspective on topological matter and open new avenues for exploration of exotic topological quantum states and topological phase transitions at higher temperatures.

关键词： quantum Hall effect without Landau levels Chern insulator topological matter topological quantum states high Chern number high temperature

FPGA based digital phase-coding quantum key distribution system

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Science China(physics,Mechanics & Astronomy) 2015年第12期58卷 153-159页

作者： LU XiaoMing Zhang LiJun WANG YongGang CHEN Wei HUANG DaJun LI Deng WANG Shuang HE DeYong YIN ZhenQiang ZHOU Yu HUI Cong HAN ZhengFu Department of Modern physics University of Science and Technology of China Key Laboratory of quantum Information University of Science and Technology of China Synergetic Innovation center of quantum Information & quantum physics University of Science and Technology of China Chinese Academy of Sciences

quantum key distribution （QKD） is a technology with the potential capability to achieve information-theoretic security. Phase- coding is an important approach to develop practical QKD systems in fiber channel. In order to improve the phase-coding modulation rate, we proposed a new digital-modulation method in this paper and constructed a compact and robust prototype of QKD system using currently available components in our lab to demonstrate the effectiveness of the method. The system was deployed in laboratory environment over a 50 km fiber and continuously operated during 87 h without manual interaction. The quantum bit error rate （QBER） of the system was stable with an average value of 3.22% and the secure key generation rate is 8.91 kbps. Although the modulation rate of the photon in the derno system was only 200 MHz, which was limited by the Faraday- Michelson interferometer （FMI） structure, the proposed method and the field programmable gate array （FPGA） based electronics scheme have a great potential for high speed QKD systems with Giga-bits/second modulation rate.

关键词： quantum key distribution phase-coding digital phase modulation field programmable gate array Faraday-Michelsoninterferometer

Detection and analysis of DNA recapture through a solid-state nanopore

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Chinese Science Bulletin 2014年第35期59卷 4953-4959页

作者： Ying Hu Zhi Zhou Xinyan Shan Xinghua Lu Institute of physics Chinese Academy of Sciences Collaborative Innovation center of quantum Matter

Motion control of a single molecule through a solid-state nanopore offers a new perspective on detecting and analyzing single *** recapture of a single DNA molecule reveals the dynamics in DNA translocation through a nanopore and may significantly increase the signal-to-noise ratio for DNA base ***,the transient current at the moment of voltage reversal prevents the observation of instantly recaptured molecules and invalidates the continuous DNA ping-pong *** performed and analyzed the DNA translocation and recapture experiment in a silicon nitride solid-state *** calculation of molecular motion clearly shows the recapture dynamics with different delay *** prohibited time when the data acquisition system is saturated by the transient current is derived by equivalent circuit analysis and finite element *** COMSOL simulation reveals that the membrane capacitance plays an important role in determining the electric field distribution during the charging *** a result of the transient charging process,a non-constant driving force pulls the DNA back to nanopores faster than theoretically *** observed long time constant in the transient current trace is explained by the dielectric absorption of the membrane capacitor.

关键词：单个DNA分子纳米孔固态检测瞬态电流数据采集系统生物分子运动控制

Phase Sensitive Photonic Flash

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Communications in Theoretical physics 2018年第8期69卷 215-219页

作者： Xin-Yun Cui Zhi-Hai Wang Jin-Hui Wu center for quantum sciences and School of physics Northeast Normal UniversityChangchun 130024China

We theoretically propose a photonic flash based on a linearly coupled cavity system. Via driving the two side cavities by external fields, it forms a cyclic energy-level diagram and therefore the phase difference between the driving fields acts as a controller of the steady state due to the quantum interference effect. In the optical trimer structure,we show that the perfect photonic flash can be realized in the situation of resonant driving. The perfect photonic flash scheme is furthermore generalized to multiple coupled cavity system, where the cavities with odd and even number turn bright and dark alternatively. Our proposal may be applied for designing the quantum neon and realizing a controllable photonic localization.

关键词： phase control photonic flash coupled cavity system

Investigation of point-contact Andreev reflection on magnetic Weyl semimetal Co3Sn2S2

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Science China(physics,Mechanics & Astronomy) 2020年第8期63卷 107-113页

作者： He Wang YanZhao Liu HuiBin Zhou HaoRan Ji JiaWei Luo JiaWei Zhang TianHeng Wei PinYuan Wang Shuang Jia Jian Wang Department of physics Capital Normal UniversityBeijing 100048China International center for quantum Materials School of PhysicsPeking UniversityBeijing 100871China Collaborative Innovation center of quantum Matter Beijing 100871China CAS center for Excellence in Topological quantum Computation University of Chinese Academy of SciencesBeijing 100190China Beijing Academy of quantum Information sciences Beijing 100193China

Magnetic Weyl semimetals(WSMs)with broken time-reversal symmetry(TRS)hosting topological band structures are expected to provide an ideal platform for investigating topological superconductivity and ***,the experimental verification of magnetic WSMs is very *** recently,the kagome magnet Co3Sn2S2 was confirmed to be a magnetic WSM by both angle-resolved photoemission spectroscopy and scanning tunneling spectroscopy and consequently has become the focus of great *** paper reports a point-contact Andreev-reflection spectroscopy(PCARS)investigation on the(001)surface and the side surface of the Co3Sn2S2 single crystals,*** measurements from the sample’s(001)and side surfaces provide experimental evidence for transport spin polarization in the Co3Sn2S2 magnetic ***,the superconducting proximity effect in the Co3Sn2S2 single crystal is successfully *** point-contact spectra(PCS)along the in-plane direction cannot be well fitted by theoretical models based on s-wave pairing,indicating that possible triplet p-wave superconductivity may be triggered at the interface,which paves the way for the future exploration of the topological superconductivity and Majorana states in broken TRS WSMs.

关键词： magnetic Weyl semimetal point contact pairing symmetry superconducting proximity effect

Precision spectroscopy of atomic helium

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National Science Review 2020年第12期7卷 1818-1827页

作者： Yu R.Sun Shui-Ming Hu Hefei National Laboratory for Physical sciences at Microscale iChem CenterUniversity of Science and Technology of China CAS center for Excellence in quantum Information and quantum physics University of Science and Technology of China

Helium is a prototype three-body system and has long been a model system for developing quantum mechanics theory and computational *** fine-structure splitting in the 2;P state of helium is considered to be the most suitable for determining the fine-structure constant α in *** more than 50 years of efforts by many theorists and experimentalists,we are now working toward a determination ofα with an accuracy of a few parts per billion,which can be compared to the results obtained by entirely different methods to verify the self-consistency of quantum ***,the precision spectroscopy of helium allows determination of the nuclear charge radius,and it is expected to help resolve the ’proton radius puzzle’.In this review,we introduce the latest developments in the precision spectroscopy of the helium atom,especially the discrepancies among theoretical and experimental results,and give an outlook on future progress.

关键词： precision spectroscopy helium, quantum electrodynamics fine-structure constant nuclear charge radius

Decoy-state measurement-device-independent quantum key distribution with mismatched-basis statistics

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Science China(physics,Mechanics & Astronomy) 2015年第9期58卷 1-4页

作者： ZHANG ChunMei LI Mo YIN ZhenQiang LI HongWei CHEN Wei HAN ZhengFu Key Laboratory of quantum Information Chinese Academy of Sciences University of Science and Technology of China Synergetic Innovation center of quantum Information & quantum physics University of Science and Technology of China

Measurement-device-independent quantum key distribution(MDI-QKD) is aimed at removing all detector side channel attacks,while its security relies on the assumption that the encoding systems including sources are fully characterized by the two legitimate parties. By exploiting the mismatched-basis statistics in the security analysis, MDI-QKD even with uncharacterized qubits can generate secret keys. In this paper, considering the finite size effect, we study the decoy-state MDI-QKD protocol with mismatchedbasis events statistics by performing full parameter optimization, and the simulation result shows that this scheme is very practical.

关键词： decoy-state method MDI-QKD full parameter optimization mismatched-basis statistics

Optical spectroscopy study of charge density wave orderOptical spectroscopy study of charge density wave order in Sr_3Rh_4Sn_(13) and (Sr_(0.5)Ca_(0.5))3_Rh_4Sn_(13)

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Science China(physics,Mechanics & Astronomy) 2017年第4期60卷 57-61页

作者： Qian Wan KuiJuan Jin JieSu Wang HongBao Yao JunXing Gu HaiZhong Guo XiuLai Xu GuoZhen Yang Beijing National Laboratory for Condensed Matter physics Institute of PhysicsChinese Academy of Sciences University of Chinese Academy of sciences Collaborative Innovation center of quantum Matter

The ultrafast laser-excited magnetization dynamics of ferromagnetic （FM） La0.67Sr0.33MnO3 （LSMO） thin films with BiFeO3 （BFO） coating layers grown by laser molecular beam epitaxy are investigated using the optical pump-probe technique. Uniform magnetization precessions are observed in the films under an applied external magnetic field by measuring the time-resolved magneto-optical Kerr effect. The magnetization precession frequencies of the LSMO thin films with the BFO coating layers are lower than those of uncoated LSMO films, which is attributed to the suppression of the anisotropy field induced by the exchange interaction at the interface between the antiferromagnetic order of BFO and the FM order of LSMO.

关键词： magnetization precession ultrafast time-resolved magneto-optical Kerr effect perovskite oxide interface

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