检索结果-内蒙古大学图书馆

Operating Single-Photon Circulator by Spinning Optical Resonators

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Li, Jing Lu, Tian-Xiang Peng, Meiyu Kuang, Le-Man Jing, Hui Zhou, Lan Key Laboratory of Low-Dimension 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 Xiangjiang-Laboratory Department of Physics Hunan Normal University Changsha410081 China Institute of Interdisciplinary Studies Hunan Normal University Changsha410081 China College of Physics and Electronic Information Gannan Normal University Jiangxi Ganzhou341000 China

A circulator is one of the crucial devices in quantum networks and simulations. We propose a four-port circulator that regulate the flow of single photons at muti-frequency points by studying the coherent transmission of a single photon in a coupled system of two resonators and two waveguides. When both resonators are static or rotate at the same angular velocity, single-photon transport demonstrates reciprocity;however, when the angular velocities differ, four distinct frequency points emerge where photon circulation can occur. In particular, when the angular velocities of the two resonators are equal and opposite, there are two different frequency points where photon circulation can be achieved, and there is a frequency point where a single photon input from any waveguide can be completely routed to the other waveguide. Interestingly, by rotating the two resonators, the single-photon circulation suppressed by the internal defect-induced backscattering can be restored. Copyright © 2024, The Authors. All rights reserved.

关键词： Angular velocity

Ferroelectrically switchable magnetic multistates in MnBi2Te4(Bi2Te3)n and MnSb2Te4(Sb2Te3)n (n = 0, 1) thin films

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Yu, Guoliang Tang, Chuhan Tian, Zhiqiang Zhu, Ziming Liu, Peitao Pan, Anlian Chen, Mingxing Chen, Xing-Qiu 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 Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang110016 China School of Materials Science and Engineering University of Science and Technology of China Shenyang110016 China Key Laboratory for Micro-Nano Physics and Technology of Hunan Province College of Materials Science and Engineering Hunan University Changsha410082 China

Ferroelectric control of two-dimensional magnetism is promising in fabricating electronic devices with high speed and low energy consumption. The newly discovered layered MnBi2Te4(Bi2Te3)n and their Sb counterparts exhibit A-type antiferromagnetism with intriguing topological properties. Here, we propose to obtain tunable magnetic multistates in their thin films by ferroelectrically manipulating the interlayer magnetic couplings (IMCs) based on the Heisenberg model and first-principles calculations. Our strategy relies on that interfacing the thin films with appropriate ferroelectric materials can switch on/off an interlayer hopping channel between Mn-eg orbitals as the polarizations reversed, thus resulting in a switchable interlayer antiferromagnetism-to-ferromagnetism transition. On the other hand, the interface effect leads to asymmetric energy barrier heights for the two polarization states. These properties allow us to build ferroelectrically switchable triple and quadruple magnetic states with multiple Chern numbers in thin films. Our study reveals that ferroelectrically switchable magnetic and topological multistates in MnBi2Te4 family can be obtained by rational design for multifunctional electronic devices, which can also be applied to other two-dimensional magnetic materials. © 2023, CC BY.

关键词： Thin films

Geometrical bounds on irreversibility in squeezed thermal bath

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Zou, Chen-Juan Li, Yue You, Jia-Bin Chen, Qiong Yang, Wan-Li Feng, Mang 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 State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan430071 China 1 Fusionopolis Way #16-16 Connexis 138632 Singapore

Irreversible entropy production (IEP) plays an important role in quantum thermodynamic processes. Here we investigate the geometrical bounds of IEP in nonequilibrium thermodynamics by exemplifying a system coupled to a squeezed thermal bath subject to dissipation and dephasing, respectively. We find that the geometrical bounds of the IEP always shift in contrary way under dissipation and dephasing, where the lower and upper bounds turning to be tighter occurs in the situation of dephasing and dissipation, respectively. However, either under dissipation or under dephasing, we may reduce both the critical time of the IEP itself and the critical time of the bounds for reaching an equilibrium by harvesting the benefits of squeezing effects, in which the values of the IEP, quantifying the degree of thermodynamic irreversibility, also becomes smaller. Therefore, due to the nonequilibrium nature of the squeezed thermal bath, the system-bath interaction energy brings prominent impact on the IEP, leading to tightness of its bounds. Our results are not contradictory with the second law of thermodynamics by involving squeezing of the bath as an available resource, which can improve the performance of quantum thermodynamic devices. © 2022, CC BY.

关键词： Entropy

Hydrogen Peroxide-Assisted Synthesis of Nitrogen/Sulfur Co-Doped Activated Carbon for High-Performance All-Printed Flexible Supercapacitor

学校读者我要写书评

暂无评论

SSRN

SSRN 2022年

作者： Hu, Leihang Song, Xianyin Zeng, Fan Liang, Jing Zhang, Xingang Zhou, Hongtao Wu, Xueli Liu, Zhi Wu, Wei Jiang, Changzhong College of Materials Science and Engineering Hunan University Changsha410082 China Laboratory of Printable Functional Materials and Printed Electronics School of Printing and Packaging Wuhan University Wuhan430072 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

Achieving more effective nitrogen/sulfur (N/S) co-doping activated carbon (AC) with superior specific surface area and pseudocapacitive remains challenging. Herein, a simple hydrogen peroxide preprocessing of commercial activated carbon has been demonstrated to dramatically promote the co-doping of N/S into AC. The N/S co-doped AC with hydrogen peroxide preprocessing (N/S-HAC) exhibits more than 2-fold increase in specific capacitance and exceptional rate capability (70% capacitance retention from 0.5 A g−1 to 100 A g−1) relative to the pristine commercial AC. Systematic experiments and characterizations reveal the significantly enhanced capacitive performances of N/S-HAC can be attributed to the etching-induced pore expansion and high-concentration nitrogen/sulfur co-doping incorporated pseudocapacitive. Furthermore, an all-printed N/S-HAC based flexible supercapacitor is fabricated by a facile screen-printing technique and shows an outstanding areal capacitance of 100 mF cm-2, energy and power density of 0.027 mWh cm-2 and 28 mW cm-2, respectively, as well as ultrahigh stability (90% capacitance retention after 20000 cycles at 10 mA cm-2). These results are superior to most of carbon-based printed flexible supercapacitors and even better than some pseudocapacitive materials. In addition, the printed flexible supercapacitor maintains stable capacitance after 1000 bending cycles, even when bent to different angles (45°, 90°, 135°, and 180°), indicating its excellent flexibility. Further, the packaged flexible supercapacitor arrays integrating multiple supercapacitors solidly light up LEDs, even during dynamic bending. This work opens a promising prospect for the development of carbon-based flexible devices with both outstanding power and energy density, remarkable stability, and excellent flexibility. © 2022, The Authors. All rights reserved.

关键词： Activated carbon

Generation and storage of spin squeezing via learning-assisted optimal control

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Tan, Qing-Shou Zhang, Mao Chen, Yu Liao, Jie-Qiao Liu, Jing 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 MOE Key Laboratory of Fundamental Physical Quantities Measurement Hubei Key Laboratory of Gravitation and Quantum Physics PGMF and School of Physics Huazhong University of Science and Technology Wuhan430074 China Tencent Lightspeed & Quantum Studios Shenzhen 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

The generation and storage of spin squeezing is an attractive topic in quantum metrology and the foundations of quantum mechanics. The major models to realize the spin squeezing are the one- and two-axis twisting models. Here, we consider a collective spin system coupled to a bosonic field, and show that proper constant-value controls in this model can simulate the dynamical behavior of these two models. More interestingly, a better performance of squeezing can be obtained when the control is time-varying, which is generated via a reinforcement learning algorithm. However, this advantage becomes limited if the collective noise is involved. To deal with it, we propose a four-step strategy for the construction of a new type of combined controls, which include both constant-value and time-varying controls, but performed at different time intervals. Compared to the full time-varying controls, the combined controls not only give a comparable minimum value of the squeezing parameter over time, but also provides a better lifetime and larger full amount of squeezing. Moreover, the amplitude form of a combined control is simpler and more stable than the full time-varying control. Therefore, our scheme is very promising to be applied in practice to improve the generation and storage performance of squeezing. © 2020, CC BY-NC-SA.

关键词： Reinforcement learning

Electronic origin of solute effects on the mobility of screw dislocation in bcc molybdenum

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Zhou, Kangzhi Feng, Jiajun Liu, Ziran Deng, Huiqiu Jia, Lixia He, Xinfu School of Physics and Electronics Hunan Normal University Hunan Changsha410081 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 Institute of Interdisciplinary Studies Hunan Normal University Hunan Changsha410081 China Hunan Provincial Key Laboratory of High-Energy Scale Physics and Applications School of Physics and Electronics Hunan University Changsha410082 China Division of Reactor Engineering Technology Research China Institute of Atomic Energy Beijing102413 China

In body-centered cubic (bcc) metals such as molybdenum, screw dislocations often exhibit non-Schmid behavior, moving in directions unpredicted by the Schmid law. The mobility of these dislocations is notably influenced by the presence of solute atoms within the alloy matrix. In this study, employing first-principles calculations, we delve into the electronic origins of these influences. Initially, we construct both single atomic column and triple atomic column models to simulate the formation of screw dislocations with solute atoms. Our investigation reveals that tantalum (Ta) and tungsten (W) increase the formation energy of solute-dislocation complexes, in contrast to osmium (Os), iridium (Ir), and platinum (Pt). Subsequently, employing a comprehensive screw dislocation dipole model under shear deformation, we explore the combined effects of solute atoms and deformation on dislocation core movement. Our findings demonstrate that Ta and W, positioned as first nearest neighbors, reduce the stress required to move dislocation cores away from corresponding dislocation dipoles. Conversely, Os, Ir, and Pt exhibit an attractive effect on dislocation cores, lowering the energy barrier for screw dislocation formation and enticing dislocation cores towards these solute atoms. Copyright © 2024, The Authors. All rights reserved.

关键词： Screw dislocations

Doping induced multiferroicity and quantum anomalous Hall effect in α-In2Se3 thin films

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Tian, Zhiqiang Li, Jin-Yang Ouyang, Tao Liu, Chao-Fei Liu, Ziran Li, Si 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 School of Physics Northwest University Shaanxi Key Laboratory for Theoretical Physics Frontiers Xi’an710127 China Hunan Key Laboratory for Micro-Nano Energy Materials and Device School of Physics and Optoelectronics Xiangtan University Hunan Xiangtan411105 China School of Science Jiangxi University of Science and Technology Ganzhou341000 China Key Laboratory for Micro-Nano Physics and Technology of Hunan Province College of Materials Science and Engineering Hunan University Changsha410082 China State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China

In flat-band materials, the strong Coulomb interaction between electrons can lead to exotic physical phenomena. Recently, α-In2Se3 thin films were found to possess ferroelectricity and flat bands. In this work, using first-principles calculations, we find that for the monolayer, there is a Weyl point at Γ in the flat band, where the inclusion of the spin-orbit coupling opens a gap. Shifting the Fermi level into the spin-orbit gap gives rise to nontrivial band topology, which is preserved for the bilayer regardless of the interlayer polarization couplings. We further calculate the Chern number and edge states for both the monolayer and bilayer, for which the results suggest that they become quantum anomalous Hall insulators under appropriate dopings. Moreover, we find that the doping-induced magnetism for In2Se3 bilayer is strongly dependent on the interlayer polarization coupling. Therefore, doping the flat bands in In2Se3 bilayer can also yield multiferroicity, where the magnetism is electrically tunable as the system transform between different polarization states. Our study thus reveals that multiferroicity and nontrivial band topology can be unified into one material for designing multifunctional electronic devices. © 2024, CC BY.

关键词： Topology

Domino cooling of a coupled mechanical-resonator chain via cold-damping feedback

学校读者我要写书评

暂无评论

Physical Review A 2021年第6期103卷 063509-063509页

作者： Deng-Gao Lai Jian Huang Bang-Pin Hou Franco Nori Jie-Qiao Liao 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 Theoretical Quantum Physics Laboratory RIKEN Cluster for Pioneering Research Wako-shi Saitama 351-0198 Japan College of Physics and Electronic Engineering Institute of Solid State Physics Sichuan Normal University Chengdu 610068 China Physics Department University of Michigan Ann Arbor Michigan 48109-1040 USA

We propose a domino-cooling method to realize simultaneous ground-state cooling of a coupled mechanical-resonator chain through an optomechanical cavity working in the unresolved-sideband regime. This domino-effect cooling is realized by combining the cold-damping feedback on the first mechanical resonator with nearest neighbor couplings between other neighboring mechanical resonators. We obtain analytical results for the effective susceptibilities, noise spectra, final mean phonon numbers, and cooling rates of these mechanical resonators, and find the optimal cooling condition for these resonators. In particular, we analyze a two-mechanical-resonator case and find that by appropriately engineering either the laser power or the feedback, a flexible switch between symmetric and asymmetric ground-state cooling can be achieved. This could be used for preparing symmetric quantum states in multimode mechanical systems. We also simulate the cooling performance of a coupled N-mechanical-resonator chain and confirm that these resonators can be simultaneously cooled to their quantum ground states in the unresolved-sideband regime. Under proper parameter conditions, the cooling of the mechanical-resonator chain shows a temperature gradient along the chain. This study opens a route to quantum manipulation of multiple mechanical resonators in the bad-cavity regime.

关键词： Optomechanics

Fast Generation of High-Fidelity Mechanical Non-Gaussian States via Additional Amplifier and Photon Subtraction

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Hu, Dong-Long Zou, Jia-Jin Sun, Feng-Xiao Liao, Jie-Qiao He, Qiongyi Xiang, Ze-Liang School of Physics Sun Yat-sen University Guangzhou510275 China State Key Laboratory for Mesoscopic Physics School of Physics Frontiers Science Center for Nano-Optoelectronics Collaborative Innovation Center of Quantum Matter Peking University Beijing100871 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

Non-Gaussian states (NGSs) with higher-order correlation properties have wide-range applications in quantum information processing. However, the generation of such states with high quality still faces practical challenges. Here, we propose a protocol to faithfully generate two types of mechanical NGSs, i.e., Schrödinger cat states and Fock states, in open optomechanical systems, even when the cooperativity is smaller than one (g2/κγ © 2022, CC BY.

关键词： Photons