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Excite atom-photon bound state inside the coupled-resonator waveguide coupled with a giant atom

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arXiv 2021年

作者： Xiao, Han Wang, Luojia Li, Zhenghong Chen, Xianfeng Yuan, Luqi State Key Laboratory of Advanced Optical Communication Systems and Networks School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Department of Physics Shanghai University Shanghai200444 China Zhejiang Province Key Laboratory of Quantum Technology and Device Zhejiang University Hangzhou310027 China Shanghai Research Center for Quantum Sciences Shanghai201315 China Jinan Institute of Quantum Technology Jinan250101 China Collaborative Innovation Center of Light Manipulation and Applications Shandong Normal University Jinan250358 China

It is of fundamental interest in controlling the light-matter interaction for a long time in the field of quantum information processing. However, usual excitation with the propagating photon can hardly excite a localized state of light while keeping the atom under a subradiant decay in an atom-waveguide system. Here, we propose a model of coupling between a giant atom and the dynamically-modulated coupled-resonator waveguide and find that a bound state, where the light shows the localization effect and atom exhibits a subradiant decay time, can be excited by a propagating photon. An analytical treatment based on the separation of the propagating states and localized states of light has been used and provides inspiring explanation of our finding, i.e., a propagating photon can be efficiently converted to the localized light through the light-atom interactions in three resonators at frequency difference precisely equivalent to external modulation frequency. Our work therefore provides an alternative method for actively localizing the photon in a modulated coupled-resonator waveguide system interacting with giant atom, and also points out a way to study the light-atom interaction in a synthetic frequency dimension that holds the similar Hamiltonian. Copyright © 2021, The Authors. All rights reserved.

关键词： Atoms

Theoretical hyperfine splittings of Be2+7,9 ions for future studies of nuclear properties

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Physical Review A 2023年第1期107卷 L010802-L010802页

作者： Xiao-Qiu Qi Pei-Pei Zhang Zong-Chao Yan Ting-Yun Shi G. W. F. Drake Ai-Xi Chen Zhen-Xiang Zhong Key Laboratory of Optical Field Manipulation of Zhejiang Province and Physics Department of Zhejiang Sci-Tech University Hangzhou 310018 China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan 430071 China Canterbury College and Department of Physics University of Windsor Windsor Ontario Canada N9B 3P4 Department of Physics University of New Brunswick Fredericton New Brunswick Canada E3B 5A3

The hyperfine structures of the 2S13 and 2PJ3 states of Be2+7 and Be2+9 are investigated within the framework of the nonrelativistic quantum electrodynamics, including relativistic and radiative corrections up to order mα6. The uncertainties of the calculated hyperfine splittings are on the order of tens of ppm, and for Be2+9 our results improve the previous theoretical and experimental values by at least two orders of magnitude. The improved sensitivity of the hyperfine splittings of Be2+7,9 to the nuclear Zemach radius and electric quadrupole moment opens the way to future measurements to extract the atomic physics values of these two nuclear properties to an accuracy of 5% or better.

关键词： Fine & hyperfine structure Relativistic & quantum electrodynamic effects in atoms, molecules,& ions First-principles calculations Perturbative methods Schroedinger equation

A simplified method characterizing magnetic ordering modulated photo-thermoelectric response in noncentrosymmetric semimetal Ca3Ru2O7

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arXiv 2023年

作者： Chen, Qiang Li, Jialin Zhu, Huanfeng Zhang, Tian Tang, Wei Xing, Hui Peng, Jin Mao, Zhiqiang Li, Linjun State Key Laboratory of Modern Optical Instrumentation College of Optical Science and Engineering Zhejiang University Hangzhou310027 China Key Laboratory of Artificial Structures and Quantum Control Shanghai Center for Complex Physics School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China School of Physics Southeast University Nanjing211189 China Department of Physics Pennsylvania State University University ParkPA16802 United States

Photo-Thermoelectric (PTE) response is usually one of the main working mechanisms for photodetectors. However, as another fast and easier way to measure thermoelectric characteristics of materials, it can also reveal important physics such as electric-phonon coupling, electron-electron correlation, etc. Recently, the spin entropy related to magnetic order transition which contributes to thermoelectric power is attracting more and more attention. Here, we demonstrate the PTE response can be reshaped when Ca3Ru2O7 undergoes meta-magnetic phase (MMP) transition driven by both temperature and magnetic field. Firstly, a sign change is observed crossing TS = 48 K and the linear polarization angle dependent PTE current maximizes along a-axis above TS while maximizes along b-axis below TS, which indicates that the antiferromagnetic spin order contributes to such spatial anisotropy. Secondly, in the temperature range of around 40 ~ 50 K, the PTE current is found to be sharply suppressed when external magnetic field is applied in plane along a-axis but is only gradually suppressed when applied field is along b-axis which gives out two critical fields. We attribute such suppression of PTE current under magnetic field to the suppression of the spin entropy in the phase transition between the antiferromagnetic state and the MMP state and the H-T phase diagrams of Ca3Ru2O7 is redrawn accordingly. Compared to previously work which trying to understand the magnetic phase transition in Ca3Ru2O7, such as neutron scattering, specific heat, and other advanced transport measurements, our work provides a more convenient yet efficient method, which may also find applications in other correlated spin materials in general. © 2023, CC BY.

关键词： Ruthenium compounds

Resource-efficient Direct Characterization of General Density Matrix

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arXiv 2023年

作者： Xu, Liang Zhou, Mingti Tao, Runxia Zhong, Zhipeng Wang, Ben Cao, Zhiyong Xia, Hongkuan Wang, Qianyi Zhan, Hao Zhang, Aonan Yu, Shang Xu, Nanyang Dong, Ying Ren, Changliang Zhang, Lijian College of Metrology and Measurement Engineering China Jiliang University Hangzhou310018 China National Laboratory of Solid State Microstructures Key Laboratory of Intelligent Optical Sensing and Manipulation College of Engineering and Applied Sciences Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210093 China Research Center for Quantum Sensing Zhejiang Lab Hangzhou310000 China School of Electronic Control Chang’an University Xi’an710064 China Quantum Optics and Laser Science Blackett Laboratory Imperial College London Prince Consort Rd LondonSW7 2AZ United Kingdom Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Key Laboratory for Matter Microstructure and Function of Hunan Province Department of Physics Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha410081 China

Sequential weak measurements allow for the direct extraction of individual density-matrix elements, rather than relying on global reconstruction of the entire density matrix, which opens a new avenue for the characterization of quantum systems. Nevertheless, extending the sequential scheme to multi-qudit quantum systems is challenging due to the requirement of multiple coupling processes for each qudit and the lack of appropriate precision evaluation. To address these issues, we propose a resource-efficient scheme (RES) that directly characterizes the density matrix of general multi-qudit systems while optimizing measurements and establishing a feasible estimation analysis. In the RES, an efficient observable of the quantum system is constructed such that a single meter state coupled to each qudit is sufficient to extract the corresponding density-matrix element. An appropriate model based on the statistical distribution of errors is utilized to evaluate the precision and feasibility of the scheme. We have experimentally applied the RES to the direct characterization of general single-photon qutrit states and two-photon entangled states. The results show that the RES outperforms sequential schemes in terms of efficiency and precision in both weak- and strong-coupling scenarios. This work sheds new light on the practical characterization of large-scale quantum systems and the investigation of their non-classical properties. © 2023, CC BY.

关键词： Photons

Fate of zero modes in a finite Su-Schrieffer-Heeger model with PT symmetry

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Physical Review A 2020年第1期101卷 013635-013635页

作者： Zhihao Xu Rong Zhang Shu Chen Libin Fu Yunbo Zhang Institute of Theoretical Physics Shanxi University Taiyuan 030006 China Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan 030006 People's Republic of China State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-Electronics Shanxi University Taiyuan 030006 People's Republic of China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100049 China Yangtze River Delta Physics Research Center Liyang Jiangsu 213300 China Graduate School of China Academy of Engineering Physics No. 10 Xibeiwang East Road Haidian District Beijing 100193 China Key Laboratory of Optical Field Manipulation of Zhejiang Province and Physics Department of Zhejiang Sci-Tech University Hangzhou 310018 China

Due to the boundary coupling in a finite system, the zero modes of a standard Su-Schrieffer-Heeger (SSH) model may deviate from exact-zero energy. A recent experiment has shown that by increasing the system size or altering gain or loss strength of the SSH model with parity-time (PT) symmetry, the real parts of the energies of the edge modes can be recovered to exact-zero value [Song et al., Phys. Rev. Lett. 123, 165701 (2019)]. To clarify the effects of PT-symmetric potentials on the recovery of the nontrivial zero modes, we study the SSH model with PT-symmetric potentials of different forms in both infinite and finite systems. Our results indicate that the energies of the edge modes in the infinite size case decide whether or not the success of the recovery of the zero modes by tuning the strength of PT-symmetric potential in a finite system. If the energies of the edge modes amount to zero in the thermodynamic limit under an open boundary condition (OBC), the recovery of the zero modes will break down by increasing the gain or loss strength for a finite system. Our results can be easily examined in different experimental platforms and inspire more insightful understanding on nontrivial edge modes in topologically non-Hermitian systems.

关键词： Edge states Polycrystalline materials quantum wires Topological insulators Tight-binding model

Measuring the non-separability of spatially disjoint vectorial fields

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arXiv 2022年

作者： Aiello, Andrea Hu, Xiao-Bo Rodríguez-Fajardo, Valeria Forbes, Andrew Hernandez-Aranda, Raul I. Perez-Garcia, Benjamin Dr, Carmelo Rosales-Guzmán Max Planck Institute for the Science of Light Staudtstrasse 2 Erlangen91058 Germany Key Laboratory of Optical Field Manipulation of Zhejiang Province Department of Physics Zhejiang Sci-Tech University Hangzhou310018 China School of Physics University of the Witwatersrand Private Bag 3 Wits 2050 South Africa Photonics and Mathematical Optics Group Tecnologico de Monterrey Monterrey64849 Mexico Centro de Investigaciones en Óptica A.C. Loma del Bosque 115 Colonia Lomas del campestre C.P. Guanajuato León37150 Mexico Wang Da-Heng Collaborative Innovation Center Heilongjiang Provincial Key Laboratory of Quantum Manipulation and Control Harbin University of Science and Technology Harbin150080 China

Vectorial forms of structured light that are non-separable in their spatial and polarisation degrees of freedom have become topical of late, with an extensive toolkit for their creation and control. In contrast, the toolkit for quantifying their non-separability, the inhomogeneity of the polarisation structure, is far less developed, and in some cases fails altogether. To overcome this, here we introduce a new measure for vectorial light, which we demonstrate both theoretically and experimentally. We consider the general case where the local polarisation homogeneity can vary spatially across the field, from scalar to vector, a condition that can arise naturally if the composite scalar fields are path separable during propagation, leading to spatially disjoint vectorial light. We show how the new measure correctly accounts for the local path-like separability of the individual scalar beams, which can have varying degrees of disjointness, even though the global vectorial field remains intact. Our work attempts to address a pressing issue in the analysis of such complex light fields, and raises important questions on spatial coherence in the context of vectorially polarised light. Copyright © 2022, The Authors. All rights reserved.

关键词： Polarization

Measurement of Hyperfine Structure and the Zemach Radius in Li+6 Using optical Ramsey Technique

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Physical Review Letters 2023年第10期131卷 103002-103002页

作者： Wei Sun Pei-Pei Zhang Peng-peng Zhou Shao-long Chen Zhi-qiang Zhou Yao Huang Xiao-Qiu Qi Zong-Chao Yan Ting-Yun Shi G. W. F. Drake Zhen-Xiang Zhong Hua Guan Ke-lin Gao State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan 430071 China Key Laboratory of Atomic Frequency Standards Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan 430071 China University of Chinese Academy of Sciences Beijing 100049 China Key Laboratory of Optical Field Manipulation of Zhejiang Province and Physics Department of Zhejiang Sci-Tech University Hangzhou 310018 China Department of Physics University of New Brunswick Fredericton New Brunswick Canada E3B 5A3 Canterbury College and Department of Physics University of Windsor Windsor Ontario Canada N9B 3P4 Center for Theoretical Physics College of Science Hainan University Haikou 570228 China

We investigate the 2S13–2PJ3 (J=0, 1, 2) transitions in Li+6 using the optical Ramsey technique and achieve the most precise values of the hyperfine splittings of the 2S13 and 2PJ3 states, with smallest uncertainty of about 10 kHz. The present results reduce the uncertainties of previous experiments by a factor of 5 for the 2S13 state and a factor of 50 for the 2PJ3 states, and are in better agreement with theoretical values. Combining our measured hyperfine intervals of the 2S13 state with the latest quantum electrodynamic (QED) calculations, the improved Zemach radius of the Li6 nucleus is determined to be 2.44(2) fm, with the uncertainty entirely due to the uncalculated QED effects of order mα7. The result is in sharp disagreement with the value 3.71(16) fm determined from simple models of the nuclear charge and magnetization distribution. We call for a more definitive nuclear physics value of the Li6 Zemach radius.

关键词： Atomic spectra Fine & hyperfine structure Relativistic & quantum electrodynamic effects in atoms, molecules,& ions optical spectroscopy Super-resolution techniques

Observation of two-vertex four-dimensional spin foam amplitudes with a 10-qubit superconducting quantum processor

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arXiv 2020年

作者： Zhang, Pengfei Huang, Zichang Song, Chao Guo, Qiujiang Song, Zixuan Dong, Hang Wang, Zhen Li, Hekang Han, Muxin Wang, Haohua Wan, Yidun Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation Zhejiang Province Key Laboratory of Quantum Technology and Device Department of Physics Zhejiang University Hangzhou310027 China State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Department of Physics Center for Field Theory and Particle Physics Institute for Nanoelectronic devices and Quantum computing Fudan University Shanghai200433 China Department of Physics Florida Atlantic University 777 Glades Road Boca RatonFL33431 United States Institut für Quantengravitation Universität Erlangen-Nürnberg Staudtstr. 7/B2 Erlangen91058 Germany Department of Physics and Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China

quantum computers are an increasingly hopeful means for understanding large quantum many-body systems bearing high computational complexity. Such systems exhibit complex evolutions of quantum states, and are prevailing in fundamental physics, e.g., quantum gravity. Computing the transition amplitudes between different quantum states by quantum computers is one of the promising ways to solve such computational complexity problems. In this work, we apply a 10-qubit superconducting quantum processor, where the all-to-all circuit connectivity enables a many-body entangling gate that is highly efficient for state generation, to studying the transition amplitudes in loop quantum gravity. With the device metrics such as qubit coherence, control accuracy, and integration level being continuously improved, superconducting quantum processors are expected to outperform their classical counterparts in handling many-body dynamics and may lead to a deeper understanding of quantum gravity. Copyright © 2020, The Authors. All rights reserved.

关键词： Qubits

Precision calculation of hyperfine structure of 7,9Be2+ ions

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arXiv 2022年

作者： Qi, Xiao-Qiu Zhang, Pei-Pei Yan, Zong-Chao Shi, Ting-Yun Drake, G.W.F. Chen, Ai-Xi Zhong, Zhen-Xiang Key Laboratory of Optical Field Manipulation of Zhejiang Province Physics Department Zhejiang Sci-Tech University Hangzhou310018 China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan430071 China Department of Physics University of New Brunswick FrederictonNBE3B 5A3 Canada Department of Physics University of Windsor WindsorONN9B 3P4 Canada

The hyperfine structures of the 2 3S1 and 2 3PJ states of the 7Be2+ and 9Be2+ ions are investigated within the framework of the nonrelativistic quantum electrodynamics (NRQED). The uncertainties of present hyperfine splitting results of 9Be2+ are in the order of several tens of ppm, where two orders of magnitude improvement over the previous theory and experiment values has been achieved. The contribution of nuclear electric quadrupole moment to hyperfine splitting of 7Be2+ has been studied. A scheme for determining the properties of Be nuclei in terms of Zemach radius or the electric quadrupole moment based on precise spectra is proposed, and it opens a new window for the study of Be nuclei. Copyright © 2022, The Authors. All rights reserved.

关键词： Atomic physics