检索结果-内蒙古大学图书馆

SSRN 2022年

作者： Le, Xianchao Zeng, Zhao-Yun Yang, Baiyuan Luo, Yunrong Xiao, Jinpeng Li, Lei Wang, Lisheng Chen, Yajiang Chen, Aixi Luo, Xiaobing Department of Physics Zhejiang Sci-Tech University Hangzhou310018 China School of Mathematics and Physics Jinggangshan University Jian343009 China Department of Physics Key Laboratory for Matter Microstructure and Function of Hunan Province Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of Ministry of Education Hunan Normal University Changsha410081 China

In this paper, we present a rigorous analysis of symmetry and underlying physics of the nonlinear two-mode system driven by a harmonic mixing field, by means of multiple scale asymptotic analysis method. The effective description in the framework of the second-order perturbative theory provides an accurate picture for understanding the Floquet eigenspectrum and dynamical features of the nonlinear two-mode system, showing full agreement with the prediction of symmetry considerations. We find that two types of symmetries play significant role in the dynamical features of this model, the mechanism behind which can be interpreted in terms of the effective description. The results are of relevance for the phase control of the atomic localization in Bose-Einstein condensates or switch of the optical signals in nonlinear mediums. © 2022, The Authors. All rights reserved.

关键词： Nonlinear analysis

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Phase control of localization in the nonlinear two-mode system from harmonic mixing driving: Perturbative analysis and symmetry consideration

arXiv

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arXiv 2022年

作者： Le, Xianchao Zeng, Zhao-Yun Yang, Baiyuan Luo, Yunrong Xiao, Jinpeng Li, Lei Wang, Lisheng Chen, Yajiang Chen, Ai-Xi Luo, Xiaobing Department of Physics Zhejiang Sci-Tech University Hangzhou310018 China School of Mathematics and Physics Jinggangshan University Ji'an343009 China Department of Physics Key Laboratory for Matter Microstructure and Function of Hunan Province Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Hunan Normal University Changsha410081 China

关键词： Statistical mechanics

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Resource-Efficient Direct Characterization of General Density Matrix

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Physical Review Letters 2024年第3期132卷 030201-030201页

作者： Liang Xu Mingti Zhou Runxia Tao Zhipeng Zhong Ben Wang Zhiyong Cao Hongkuan Xia Qianyi Wang Hao Zhan Aonan Zhang Shang Yu Nanyang Xu Ying Dong Changliang Ren Lijian Zhang College of Metrology & Measurement Engineering China Jiliang University Hangzhou 310018 China National Laboratory of Solid State Microstructures Key Laboratory of Intelligent Optical Sensing and Manipulation College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China Research Center for Quantum Sensing Zhejiang Lab Hangzhou 310000 China School of Electronic Control Chang’an University Xi’an 710064 China Quantum Optics and Laser Science Blackett Laboratory Imperial College London Prince Consort Road London SW7 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 and Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha 410081 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 multiqudit 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 multiqudit 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 Letter sheds new light on the practical characterization of large-scale quantum systems and the investigation of their nonclassical properties.

关键词： Optical quantum information processing Quantum foundations Quantum measurements Quantum tomography Weak values & weak measurements Weak measurements

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Controlling the qubit-qubit coupling in the superconducting circuit with double-resonator couplers

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Physical Review A 2024年第1期109卷 012601-012601页

作者： Hui Wang Yan-Jun Zhao Hui-Chen Sun Xun-Wei Xu Yong Li Yarui Zheng Qiang Liu Rengang Li Shandong Inspur Intelligence Research Institute Co. Ltd. Jinan 250100 China Shandong Yunhai Guochuang Innovative Technology Co. Ltd. Jinan 250101 China Key Laboratory of Opto-electronic Technology Ministry of Education Beijing University of Technology Beijing 100124 China Institute for Quantum Computing and Department of Physics and Astronomy University of Waterloo Waterloo Ontario N2L 3G1 Canada 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 and Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha 410081 China Quantum Element Technology (Shen Zhen) Co. Ltd. Shenzhen 518048 China

We propose a theoretical scheme of using two fixed-frequency resonator couplers to tune the interaction between two Xmon qubits. The indirect interaction between two qubits induced by two resonators can cancel each other, so direct qubit-qubit coupling is not essential for the switching off. So, we can suppress the static ZZ coupling with the weak direct qubit-qubit coupling and even eliminate the static ZZ coupling through the destructive interferences of the double-path couplers. The cross-Kerr resonance can induce additional poles for the static ZZ coupling which should be kept away during the two-qubit gates. The double-resonator couplers scheme could unfreeze some restrictions during the design of superconducting quantum chips and mitigate the static ZZ coupling, which might supply a promising platform for future superconducting quantum chips.

关键词： Quantum computation Quantum control

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Ultrafast growth of high-quality large-sized GaSe crystals by liquid metal promoter

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Nano Research 2022年第5期15卷 4677-4681页

作者： Zuxin Chen Quan Chen Zebing Chai Bin Wei Jun Wang Yanping Liu Yumeng Shi Zhongchang Wang Jingbo Li Institute of semiconductors South China Normal UniversityGuangzhou 510631China School of Materials Sun Yat-Sen UniversityGuangzhou 510275China School of Electrical Engineering and Automation Wuhan UniversityWuhan 430000China School of Physics and Electronics Hunan Key Laboratory for Super-microstructure and Ultrafast ProcessCentral South University932 South Lushan RoadChangsha 410083China Engineering Technology Research Center for 2D Material Information Function Devices and Systems of Guangdong Province International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of EducationInstitute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060China International Iberian Nanotechnology Laboratory(INL) 4715–330 BragaPortugal

Growth of high-quality large-sized crystals using the traditional chemical vapor transport(CVT)or vertical Bridgman(VB)technique is costly and time-consuming,limiting its practical industrial ***,we propose an ultrafast crystal growth process with low energy consumption and capability of producing crystals of excellent quality,and demonstrate that large-sized GaSe crystals with a lateral size of 0.5 to 1 cm can be obtained within a short period of 5 min.X-ray diffraction(XRD)and scanning transmission electron microscopy(STEM)studies clearly indicate that the as-grown crystals have a good *** further show the potential application of the resulting GaSe crystals,we fabricate the few-layer GaSe-based photodetector,which exhibits low dark current of 21 pA and fast response of 34 ms under 405 nm *** proposed technique for rapid crystal growth could be further extended to other metallenes with low-melting point,such as Bi-,Sn-,In-,Pb-based crystals,opening up a new avenue in fulfilling diverse potential optoelectronics applications of two-dimensional(2D)crystals.

关键词： GaSe ultrafast growth photodetector liquid metal

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Nonreciprocal photon blockade and directional amplification in a spinning resonator coupled to a two-level atom

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Physical Review A 2021年第3期104卷 033707-033707页

作者： Yu-Wei Jing Hai-Quan Shi Xun-Wei Xu 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 and Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha 410081 China Department of Applied Physics East China Jiaotong University Nanchang 330013 China

We propose a scheme to realize nonreciprocal photon blockade and directional amplification in a spinning resonator with clockwise and counterclockwise traveling modes coupled to a stationary two-level atom. By manipulating the rotational frequency of the resonator, the two-level atom can be resonant with one of the traveling modes and largely detuned from the other one. Nonreciprocal conventional photon blockade is induced by the difference of the detunings between the two-level atom and the optical modes traveling in different directions. Besides that, nonreciprocal unconventional photon blockade (UPB) based on the quantum interference can also be observed in the system. Based on the mechanism for nonreciprocal UPB, directional amplification of the blockaded photons is predicted by driving the spinning resonator and stationary two-level atom simultaneously. Our proposal will be applicable to achieve highly efficient nonreciprocal single-photon devices for applications in chiral quantum information processing.

关键词： Cavity quantum electrodynamics Coherent control Optomechanics Photon statistics Quantum optics Optical microcavities Jaynes-Cummings model

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Optimal control of linear Gaussian quantum systems via quantum learning control

arXiv

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arXiv 2024年

作者： Liu, Yu-Hong Zeng, Yexiong Tan, Qing-Shou Dong, Daoyi 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 Theoretical Quantum Physics Laboratory Cluster for Pioneering Research RIKEN Wakoshi Saitama351-0198 Japan Quantum Computing Center RIKEN Wakoshi Saitama351-0198 Japan Key Laboratory of Hunan Province on Information Photonics and Freespace Optical Communication College of Physics and Electronics Hunan Institute of Science and Technology Yueyang414000 China School of Engineering and Information Technology University of New South Wales CanberraACT2600 Australia Department of Physics The University of Michigan Ann ArborMI48109-1040 United States Institute of Interdisciplinary Studies Hunan Normal University Changsha410081 China

Efficiently controlling linear Gaussian quantum (LGQ) systems is a significant task in both the study of fundamental quantum theory and the development of modern quantum technology. Here, we propose a general quantum-learning-control method for optimally controlling LGQ systems based on the gradient-descent algorithm. Our approach flexibly designs the loss function for diverse tasks by utilizing first- and second-order moments that completely describe the quantum state of LGQ systems. We demonstrate both deep optomechanical cooling and large optomechanical entanglement using this approach. Our approach enables the fast and deep ground-state cooling of a mechanical resonator within a short time, surpassing the limitations of sideband cooling in the continuous-wave driven strong-coupling regime. Furthermore, optomechanical entanglement could be generated remarkably fast and surpass several times the corresponding steady-state entanglement, even when the thermal phonon occupation reaches one hundred. This work will not only broaden the application of quantum learning control, but also open an avenue for optimal control of LGQ systems. Copyright © 2024, The Authors. All rights reserved.

关键词： Cooling

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Cosmological constraints from type-I radio-loud quasars

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Physical Review D 2024年第4期109卷 043529-043529页

作者： L. Huang Z. Y. Tu N. Chang F. F. Song F. He X. Y. Fu College of Science Jiujiang University Jiujiang 332000 People’s Republic of China Jiangxi Province Key Lab of Microstructure Function Materials Jiujiang 332000 People’s Republic of China Xinjiang Astronomical Observatory Chinese Academy of Sciences Urumqi 830011 People’s Republic of China Key Laboratory of Radio Astronomy Chinese Academy of Sciences Nanjing 210008 People’s Republic of China Institute of Physics Hunan University of Science and Technology Xiangtan Hunan 411201 People’s Republic of China

We obtain a sample of 1192 type-I quasars with the UV-optical, radio, and x-ray waveband coverage, which combined with the data from Huang and Chang [Mon. Not. R. Astron. Soc. 515, 1358 (2022)] and other matching objects of SDSS-DR16 with FIRST, XMM-Newton, and Chandra Source Catalog, and a sample of 407 flat-spectrum radio-loud quasars of blazars from the Roma-BZCAT, which can be used to investigate their multiband luminosity correlations and measure the luminosity distances of these type-I radio-loud quasar (RLQ) samples. We check the correlation between x-ray, UV-optical, and radio luminosity for various groupings of radio-quiet quasars (RQQs) and RLQs by parametrizing x-ray luminosity as a sole function of UV-optical or radio luminosity and as a joint function of UV/optical radio luminosity, which also can be employed to determine these cosmological distances. By Bayesian information criterion, the data suggest that the x-ray luminosity of RQQs is indirectly correlative with radio luminosity because of the connection between UV-optical and radio luminosity. However for RLQs, the x-ray luminosity is directly related to radio luminosity, and the correlations between x-ray, optical/UV, and radio luminosity get stronger with the increase in the ratio of monochromatic luminosities. Furthermore, we compare the results from RLQs with different UV-optical power-law index ΓUV, and find that the goodness of fit for RLQs with ΓUV≤1.6 is tentatively better. Finally, we apply a combination of type-I RLQs and Type Ia supernova (SN Ia) Pantheon to verify the nature of dark energy concerning whether or not its density deviates from the constant, and the statistical results indicate that the Lambda cold dark matter model may be in tension with type-I RLQs at ∼1.5σ.

关键词： Cosmological parameters Cosmology Dark energy Formation & evolution of stars & galaxies Optical, UV, & IR astronomy Active & peculiar galaxies Astrophysical jets Galactic nuclei & quasars

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Direct measurement of density-matrix elements using a phase-shifting technique

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Physical Review A 2021年第4期104卷 042403-042403页

作者： Tianfeng Feng Changliang Ren Xiaoqi Zhou State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics Sun Yat-sen University Guangzhou 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 and Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha 410081 China

A direct measurement protocol allows reconstructing specific elements of the density matrix of a quantum state without using quantum state tomography. However, the direct measurement protocols to date are primarily based on weak or strong measurements with an ancillary pointer, which interacts with the investigated system to extract information about the specified elements. Here, we present a direct measurement scheme based on phase-shifting operations which do not need ancillary pointers. In this method, estimates of at most six expectation values of projective observables suffice to determine any specific element of an unknown quantum density matrix. A concrete quantum circuit to implement this direct measurement protocol for multiqubit states is provided, which is composed of just single-qubit gates and two multiqubit controlled-phase gates. This scheme is also extended for the direct measurement of the density matrix of continuous-variable quantum states. Our method can be used in quantum information applications where only partial information about the quantum state needs to be extracted, for example, problems such as entanglement witnessing, fidelity estimation of quantum systems, and quantum coherence estimation.

关键词： Quantum algorithms Quantum information processing Quantum measurements Quantum protocols Quantum tomography

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Interface engineering of ferroelectricity in thin films of thiophosphate ABP2X6 (A = Cu, Ag;B = In, Bi, Cr, V;and X = S, Se)

arXiv

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arXiv 2021年

作者： Yu, Guoliang Pan, Anlian Chen, Mingxing Key Laboratory for Matter Microstructure and Function of Hunan Province Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education School of Physics and Electronics Hunan Normal University Changsha410081 China Key Laboratory for Micro-Nano Physics and Technology of Hunan Province College of Materials Science and Engineering Hunan University Changsha410082 China

Two-dimensional ferroelectrics (FEs) are promising in the miniaturization of memory devices with ultra-high-density data storage and low power consumption. However, many thiophosphate monolayers, i.e., analogs of CuInP2S6 and referred to as ABP2X6, lose ferroelectricity and instead exhibit an antiferroelectric (AFE) or paraelectric ordering. We propose to tune the AFE ABP2X6 monolayers into the FE ordering through interface engineering. The mechanism is that there are couplings between the charge polarizations of the ABP2X6 monolayers and the local dipoles as well as the induced electronic polarizations in the substrate which have a tendency to stabilize the FE ordering. We further perform first-principles calculations for CuInP2Se6 and CuCrP2S6 monolayers and their van der Waals heterostructures. We find that an AFE CuInP2Se6 monolayer becomes FE as interfaced with graphene, MoS2, and h-BN monolayers. In contrast, the CuCrP2S6 monolayer remains AFE since there is a large energy difference between the AFE and FE phases. Interfacing it with a MoTe2 monolayer induces a metal-insulator transition for the heterostructure, whereas interfacing with a polar surface MgO(111) can drive it into FE. The interfacing effect can also be used to manipulate the FE properties of ABP2X6 multilayers. We further find that the AFE-to-FE transition is electrically switchable in these systems. In particular, it is accompanied by an indirect-direct band-gap transition for the CuInP2Se6 monolayer. Our study offers an effective approach to tune the FE and electronic properties of ABP2X6 thin films for applications in electronics and optoelectronics. © 2021, CC BY.

关键词： Monolayers

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