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Quantum excitation transfer in bosonic networks: a bipartite-graph framework

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arXiv 2025年

作者： Liu, Cheng Liu, Yu-Hong Kuang, Le-Man Nori, Franco Liao, Jie-Qiao 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 Hunan Research Center of the Basic Discipline for Quantum Effects and Quantum Technologies Hunan Normal University Changsha410081 China Quantum Computing Center RIKEN Saitama Wakoshi351-0198 Japan Department of Physics The University of Michigan Ann ArborMI48109-1040 United States Institute of Interdisciplinary Studies Hunan Normal University Changsha410081 China

Highly efficient transfer of quantum resources including quantum excitations, states, and information on quantum networks is an important task in quantum information science. Here, we propose a bipartite-graph framework for studying quantum excitation transfer in bosonic networks by diagonalizing the intermediate sub-network between the sender and the receiver to construct a bipartite-graph configuration. We examine the statistical properties of the bosonic networks in both the original and bipartite-graph representations. In particular, we investigate quantum excitation transfer in both the finite and infinite intermediate-normal-mode cases, and show the dependence of the transfer efficiency on the network configurations and system parameters. We find the bound of maximally transferred excitations for various network configurations and reveal the underlying physical mechanisms. We also find that the dark-mode effect will degrade the excitation transfer efficiency. Our findings provide a new insight for the design and optimization of quantum networks. Copyright © 2025, The Authors. All rights reserved.

关键词： Graphic methods

Negative electrocaloric effect in nonpolar phases of perovskite over wide range of temperature

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arXiv 2023年

作者： Ma, Xingyue Chen, Mingxing Liu, Jun-Ming Wu, Di Yang, Yurong National Laboratory of Solid State Microstructures and Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210093 China Jiangsu Key Laboratory of Artificial Functional Materials Department of Materials Science and Engineering Nanjing University Nanjing210093 China School of Physics and Electronics Hunan Normal University Key Laboratory for Matter Microstructure and Function of Hunan Province Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Changsha410081 China

The electrocaloric effect (ECE) offers a promising alternative to the traditional gas compressing refrigeration due to its high efficiency and environmental friendliness. The unusual negative electrocaloric effect refers to the adiabatic temperature drops due to application of electric field, in contrast with the normal (positive) ECE, and provides ways to improve the electrocaloric efficiency in refrigeration cycles. However, negative ECE is unusual and requires a clear understanding of microscopic mechanisms. Here, we found unexpected and extensive negative ECE in nonpolar orthorhombic, tetragonal, and cubic phases of halide and oxide perovskite at wide range of temperature by means of first-principle-based large scale Monte Carlo methods. Such unexpected negative ECE originates from the octahedral tilting related entropy change rather than the polarization entropy change under the application of electric field. Furthermore, a giant negative ECE with temperature change of 8.6 K is found at room temperature. This giant and extensive negative ECE in perovskite opens up new horizon in the research of caloric effects and broadens the electrocaloric refrigeration ways with high efficiency. Copyright © 2023, The Authors. All rights reserved.

关键词： Perovskite

Controllable non-Hermitian Qubit-Qubit Coupling in Superconducting Quantum Circuit

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arXiv 2024年

作者： Wang, Hui Zhao, Yan-Jun Xu, Xun-Wei Inspur artificial intelligence research institute Jinan250014 China Shandong Yunhai Guochuang Innovative Technology Co. Ltd. Jinan250101 China Key Laboratory of Opto-electronic Technology Ministry of Education Beijing University of Technology Beijing100124 China 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

We propose a theoretical scheme to realize the controllable non-Hermitian qubit-qubit coupling by adding a high-loss resonator in tunable coupling superconducting quantum circuit. By changing the effective qubit-qubit coupling, phase and amplitude of resonator-qubit interaction, and the qubits’ quantum states, we can continually tune the energy level attraction, position of EP (exceptional point), and the nonreciprocity in the non-Hermitian superconducting circuit. The EPs and non-reciprocity can affect the quantum states’ evolutions and exchange efficiencies for two qubits in the non-Hermitian superconducting circuit. The controllable non-Hermitian and nonreciprocal interactions between two qubits provide a new insights and methods for exploring the unconventional quantum effects in superconducting quantum circuit. © 2024, CC BY.

关键词： Qubits

Dynamical emission of phonon pairs in optomechanical systems

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Physical Review A 2022年第5期105卷 053507-053507页

作者： Fen Zou Jie-Qiao Liao Yong Li Beijing Computational Science Research Center Beijing 100193 China 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 Hunan Normal University Changsha 410081 China Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha 410081 China Center for Theoretical Physics and School of Science Hainan University Haikou 570228 China

The multiphonon state plays an important role in quantum information processing and quantum metrology. Here we propose a scheme to realize dynamical emission of phonon pairs based on the technique of stimulated Raman adiabatic passage in a single-cavity optomechanical system, where the optical cavity is driven by two Gaussian pulse lasers. By exploring quantum trajectories of the state populations and the average phonon number, we find that the dynamical phonon-pair emission can be realized under the appropriate parameter conditions and is tunable by controlling the time interval between the consecutive pulses of pump lasers. In particular, the numerical results for the standard and generalized second-order correlation functions of the mechanical mode show that the system can behave as an antibunched phonon-pair emitter. Our proposal can be extended to achieve an antibunched n-phonon emitter, which has potential applications for on-chip quantum communication.

关键词： Optomechanics Photon statistics

Dynamical N-photon bundle emission

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arXiv 2023年

作者： Zou, Fen Li, Yong Liao, Jie-Qiao 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 Hunan Normal University Changsha410081 China Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha410081 China Beijing Computational Science Research Center Beijing100193 China Center for Theoretical Physics School of Science Hainan University Haikou570228 China

Engineering multiphoton resources is of importance in quantum metrology, quantum lithography, and biological sensing. Here we propose a concept of dynamical emission of N strongly-correlated photons. This is realized in a circuit quantum electrodynamical system driven by two Gaussian-pulse sequences. The underlying physical mechanism relies on the stimulated Raman adiabatic passage that allows efficient and selective preparation of target multiphoton states. Assisted by the photon decay, a highly pure N-photon bundle emission takes place in this system. In particular, the dynamical N-photon bundle emission can be tuned by controlling the time interval between consecutive pulses so that the device behaves as an Nphoton gun, which can be triggered on demand. Our work opens up a route to achieve multiphoton source devices, which have wide potential applications in quantum information processing and quantum metrology. Copyright © 2023, The Authors. All rights reserved.

关键词： Photons

High-mobility two-dimensional MA2N4 (M = Mo, W;A = Si, Ge) family for transistors

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Physical Review B 2024年第11期109卷 115427-115427页

作者： Wei-Hua Xiao Kaike Yang Roberto D'Agosta Hong-Rui Xu Gang Ouyang Guanghui Zhou Ke-Qiu Chen Li-Ming Tang Department of Applied Physics School of Physics and Electronics Hunan University Changsha 410082 China Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Key Laboratory for Matter Microstructure and Function of Hunan Province Synergetic Innovation Center for Quantum Effects and Applications Department of Physics Hunan Normal University Changsha 410081 China Nano-Bio Spectroscopy Group and European Theoretical Spectroscopy Facility (ETSF) Departamento de Polimeros y Materiales Avanzados: Fisica Quimica y Tecnologia Universidad del Pais Vasco (UPV/EHU) Avenida de Tolosa 72 E-20018 San Sebastian Ikerbasque Basque Foundation for Science Plaza de Euskadi 5 E-48009 Bilbao Spain

The quest for functional materials for the next generation of electronics plays a pivotal role in the postsilicon era, and two-dimensional layered semiconductors are at the core of this extensive research. In this work, we demonstrate that some members of the MA2Z4 family are candidates for high-efficiency optoelectronics. Through first-principles calculations, we find that the intrinsic electron mobility of MA2N4 (where M = {Mo, W} and A = {Si, Ge}) layer materials reaches up to 103cm2/Vs at liquid nitrogen temperature, and decreases as the temperature rises due to the enhanced electron-phonon scattering. Interestingly, the charge transport in these materials takes place purely along the intercalated transition metal nitride layer, so the surface adsorptions (impurities) or substrate interactions have nearly no effect on the carrier mobility due to the A-N bilayer protection, and the high electron mobility does not depend on the thickness of the sample. These features are distinct from other two-dimensional (2D) materials, such as silicene, black phosphorus, and indium selenide, and the 2D MA2Z4 family of materials are proposed as an outstanding candidate for field effect transistors and further studies.

关键词： Electrical conductivity Electronic structure 2-dimensional systems First-principles calculations

Two-dimensional hourglass Weyl nodal loop in monolayer Pb(ClO2)2 and Sr(ClO2)2

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arXiv 2022年

作者： Kang, Xin-Yue Zhang, Chunmei Chen, Mingxing Li, Si School of Physics Northwest University Xi’an710127 China Shaanxi Key Laboratory for Theoretical Physics Frontiers Xi’an710127 China School of Physics and Electronics Hunan Normal University Key Laboratory for Matter Microstructure and Function of Hunan Province Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control Ministry of Education Changsha410081 China

The hourglass fermions in solid-state materials have been attracting significant interest recently. However, realistic two-dimensional (2D) materials with hourglass-shaped band structures are still very scarce. Here, through the first-principles calculations, we identify the monolayer Pb(ClO2)2 and Sr(ClO2)2 materials as the new realistic materials platform to realize 2D hourglass Weyl nodal loop. We show that these monolayer materials possess an hourglass Weyl nodal loop circling around the Γ point and Weyl nodal line on the Brillouin zone (BZ) boundary in the absence of spin-orbit coupling (SOC). Through the symmetry analysis, we demonstrate that the hourglass Weyl nodal loop and Weyl nodal line are protected by the nonsymmorphic symmetries, and are robust under the biaxial strains. When we include the SOC, a tiny gap will be opened in the hourglass nodal loop and nodal line, and the nodal line can be transformed into the spin-orbit Dirac points. Our results provide a new realistic material platform for studying the intriguing physics associated with the 2D hourglass Weyl nodal loop and spin-orbit Dirac points. © 2022, CC BY-NC-ND.

关键词： Chlorine compounds

Understanding the nature of Ω(2012) in a coupled-channel approach

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Physical Review D 2023年第1期107卷 014025-014025页

作者： Qi-Fang Lü Hideko Nagahiro Atsushi Hosaka Department of Physics Hunan Normal University and Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Changsha 410081 China Key Laboratory for Matter Microstructure and Function of Hunan Province Hunan Normal University Changsha 410081 China Research Center for Nuclear Physics (RCNP) Ibaraki Osaka 567-0047 Japan Department of Physics Nara Women’s University Nara 630-8506 Japan Advanced Science Research Center Japan Atomic Energy Agency Tokai Ibaraki 319-1195 Japan

We perform a systematic analysis of the mass and strong decays of the Ω(2012) resonance in a coupled-channel approach of a bare three-quark state and a composite meson-baryon state. Besides the coupling of the bare state and Ξ*K¯ channel, the effective meson-baryon interactions are also included. We find a pole with a mass of 2008 MeV by solving the Bethe-Salpeter equation. The calculated decay widths and its ratios of branching fractions RΞK¯ΞπK¯ agree well with the new experimental measurement by the Belle Collaboration. Our results suggest that both three-quark core and Ξ*K¯ channel are essential for the description of the Ω(2012) resonance. We expect that present calculations can help us to better understand the nature of Ω(2012) resonance.

关键词： Hadronic decays Hyperons Mass

Quantum thermalization and thermal entanglement in the open quantum Rabi model

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arXiv 2022年

作者： Liu, Wang-Yan Fan, Li-Bao Zeng, Ye-Xiong Huang, Jin-Feng Liao, Jie-Qiao 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 Hunan Key Laboratory of Nanophotonics and Devices Hunan Key Laboratory of Super-Microstructure and Ultrafast Process School of Physics and Electronics Central South University Changsha410083 China Theoretical Quantum Physics Laboratory RIKEN Cluster for Pioneering Research Saitama Wako-shi351-0198 Japan

We study quantum thermalization and thermal entanglement in the open quantum Rabi model (QRM), in which a two-level system and a single-mode bosonic field are coupled to either two individual heat baths or a common heat bath. By treating the QRM as an effective multilevel system and deriving global quantum master equations in the eigenstate representation of the QRM, we study the physical conditions for quantum thermalization of the QRM. It is found that, in the individual heat-bath case, the QRM can only be thermalized when either the two heat baths have the same temperature or the QRM is only coupled to one of the two baths. In the common heat-bath case, differently, the QRM can always be thermalized. We also study thermal entanglement of the QRM in both the resonant- and non-resonant coupling cases. The logarithmic negativity for the thermal state of the QRM is obtained in a wide parameter space, ranging from the low- to high-temperature limits, and from the weak- to deep-strong-coupling regimes. This work paves the way towards the study of quantum effects in nonequilibrium ultrastrongly-coupled light-matter systems. Copyright © 2022, The Authors. All rights reserved.

关键词： Quantum entanglement