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Wave packet dynamics of entangled q-deformed states

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arXiv 2024年

作者： Rohith, M. Anupama, S. Sudheesh, C. Quantum Systems Lab Department of Physics Government College Malappuram University of Calicut Malappuram676 509 India P. G. & Research Department of Physics Government Arts and Science College University of Calicut Kozhikode673 018 India Department of Physics Indian Institute of Space Science and Technology Thiruvananthapuram695 547 India

This paper explores the wave packet dynamics of a math-type q-deformed field interacting with atoms in a Kerr-type nonlinear medium. The primary focus is on the generation and dynamics of entanglement using the q-deformed field, with the quantification of entanglement accomplished through the von Neumann entropy. Two distinct initial q-deformed states, the q-deformed Fock state, and the q-deformed coherent state, are investigated. The entanglement dynamics reveal characteristics of periodic, quasi-periodic, and chaotic behavior. Non-deformed initial states display wave packet near revivals and fractional revivals in entanglement dynamics while introducing q-deformation eliminates these features. The q-deformation significantly influences wave packet revivals and fractional revivals, with even a slight introduction causing their disappearance. For large values of q, the entanglement dynamics exhibit a chaotic nature. In the case of a beam splitter-type interaction applied to the initial deformed Fock state, an optimal deformation parameter q is identified, leading to maximum entanglement exceeding the non-deformed scenario. © 2024, CC BY.

关键词： Wave packets

The cooperative migration dynamics of particles correlates to the nature of hexatic-isotropic phase transition in 2D systems of corner-rounded hexagons

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Fundamental Research 2024年第2期4卷 284-290页

作者： Zhanglin Hou Mingwei Liu Yiwu Zong Fangfu Ye Kun Zhao Wenzhou Institute University of Chinese Academy of SciencesWenzhouZhejiang 325001China Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering(Ministry of Education) School of Chemical Engineering and TechnologyTianjin 300072China School of Physical Science University of Chinese Academy of SciencesBeijing 100049China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Oujiang Laboratory(Zhejiang Lab for Regenerative Medicine Vision and Brain Health)WenzhouZhejiang 325001China Sichuan Provincial People’s Hospital University of Electronic Science and Technology of ChinaChengduSichuan 610054China Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengduSichuan 610054China

In the two-dimensional(2D)melting transition of colloidal systems,the hexatic-isotropic(H-I)transition can be either first-order or ***,how particle dynamics differs at the single-particle level during these two different melting transitions remains to be *** this work,by Brownian dynamics(BD)simulations,we have systematically studied the dynamic behavior of corner-rounded hexagons during the H-I transition,for a range of corner-roundness𝜁=0.40 to 0.99 that covers the crossover from the continuous to first-order nature of H-I *** results show that hexagons with𝜁≤0.5 display a continuous H-I transition,whereas those with𝜁≥0.6 demonstrate a first-order H-I *** analysis shows different evolution pathways of the dominant cluster formed by migrating particles,which results in a droplet-like cluster structure for𝜁=0.40 hexagons and a tree-like cluster structure for𝜁=0.99 *** investigations on the hopping activities of particles suggest a cooperative origin of migrating *** work provides a new aspect to understand the dependence of the nature of H-I transition on the roundness of hexagons through particle dynamic behavior.

关键词： Melting transition Colloids Hexatic phase Cooperative migration Hexagons

Probing the antiferromagnetic structure of bilayer CrI3 by second harmonic generation: A first-principles study

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Physical Review B 2022年第23期106卷 235410-235410页

作者： ZhenHua Li Zhi-Ming Yu JianHua Wei Hong-Gang Luo School of Physical Science and Technology & Lanzhou Center for Theoretical Physics & Key Laboratory of Theoretical Physics of Gansu Province Lanzhou University Lanzhou 730000 China Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100081 China Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China Department of Physics Renmin University of China Beijing 100872 China

Two-dimensional antiferromagnetic materials with robust second harmonic generation (SHG) have been attracting significant research interest. In recent experiments, enhanced SHG from layered antiferromagnet (AFM) bilayer chromium trioxide (CrI3) with A-type antiferromagnetic order has been observed. However, bilayer CrI3 with A-type, C-type, and G-type antiferromagnetic order may simultaneously occur in experimental synthesis, as the total free-energy difference between the three AFMs is small. Here, based on symmetry analysis and first-principles calculations, we study the three kinds of bilayer AFMs with and without the spin-orbit coupling (SOC) effect. We find that for all three types, the i-type SHG response vanishes due to the centrosymmetric lattice structure. However, significant c-type SHG response can arise in A-type and C-type AFMs but still vanishes for G-type AFM. Under normal incidence, both A-type and C-type AFMs exhibit three independent nonvanishing SHG components. Remarkably, the nonvanishing SHG components of A-type and C-type AFMs are mutually exclusive, namely, the SHG components that are finite for A-type vanish for C-type and vice versa. In particular, the SHG of both A-type and C-type AFMs is sensitive to the SOC effect and it becomes enhanced when the SOC effect is fully considered. Hence, the SHG response would be an efficient method for probing bilayer CrI3 with different antiferromagnetic orders.

关键词： Magnetic order Optoelectronics Layered crystals Magnetic multilayers Density functional theory Symmetries

Isolated Cu-Sn diatomic sites for enhanced electroreduction of CO_(2)to CO

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Nano Research 2023年第7期16卷 8729-8736页

作者： Wei Liu Haoqiang Li Pengfei Ou Jing Mao Lili Han Jun Song Jun Luo Huolin L.Xin State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Department of Physics and Astronomy University of CaliforniaIrvineCA 92697USA Tsinghua Shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China School of Materials Science and Engineering Tianjin Key Lab of Photoelectric Materials&DevicesTianjin University of TechnologyTianjin 300384China Department of Mining and Materials Engineering McGill UniversityMontreal H3A 0C5Canada Teaching and Analytical Instrumentation Center School of Materials Science and EngineeringTianjin UniversityTianjin 300072China

Electrochemical CO_(2)reduction reaction(CO_(2)RR)to high-value product,CO,not only provides a key feedstock for the wellestablished Fischer-Tropsch process but also mitigates the greenhouse ***,it suffers from sluggish reaction kinetics,competitive hydrogen evolution reaction,and low ***,we report non-precious Cu-Sn diatomic sites anchored on nitrogen-doped porous carbon(CuSn/NPC)as an efficient catalyst for CO_(2)RR to *** catalyst exhibits outstanding selectivity with CO Faradaic efficiency(FE)up to 99.1%,much higher than those of individual Cu(66.2%)and Sn(51.3%)single-atom ***,high stability is confirmed by consecutive 24 h electrolysis with high selectivity from CO_(2)to *** calculations reveal an obvious activation of CO_(2)with weakened C-O bonds and distorted CO_(2)configuration upon chemisorption on the CuSn/NPC *** is also suggested CuSn/NPC is more selective for the CO_(2)RR with dominant CO production during the electrolysis,rather than the competing hydrogen evolution reaction.

关键词： CO_(2)reduction reaction Cu-Sn active site CO product dual-atom electrocatalyst density functional theory(DFT)calculation

Surface Coating Changes the Phytotoxicity of Ceo2 Nanoparticles to Duckweed (Lemna Minor L.)

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SSRN

SSRN 2024年

作者： Zhao, Xuepeng Ma, Yuhui Dai, Wanqin Song, Zhuda Wang, Yun Shen, Jiaqi He, Xiao Yang, Fang Zhang, Zhiyong Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety & CAS-HKU Joint Laboratory of Metallomics on Health and Environment Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China Hebei Provincial Key Lab of Green Chemical Technology & High Efficient Energy Saving School of Chemical Engineering and Technology Hebei University of Technology Tianjin300130 China School of Nuclear Science and Technology University of the Chinese Academy of Sciences Beijing100049 China Hebei University of Technology China

Little is known about the effect of surface coatings on the fate and toxicity of CeO2 nanoparticles (NPs) in aquatic plants. In this study, we modified nCeO2 with chitosan (Cs) and alginate (Al) to obtain positively charged nCeO2@Cs and negatively charged nCeO2@Al, respectively, and exposed them to a representative aquatic plant, duckweed (Lemna minor L.). Uncoated nCeO2 could significantly inhibit the growth of duckweed, induce oxidative damage and lead to cell death, whereas nCeO2@Cs and nCeO2@Al exhibited lower toxicity to duckweed. ICP-MS analysis revealed that the Ce content in duckweed from the nCeO2 group was 1.74 and 2.85 times higher than that in the nCeO2@Cs and nCeO2@Al groups, respectively. This might be due to that coatings changed the surface properties of nCeO2, thereby affecting its bioavailability. Microscopic observations indicated that the positively charged nCeO2@Cs was more readily adsorbed on the root surface of duckweed than the negatively charged nCeO2@Al. The results of XANES and LCF demonstrated that a certain percentage of Ce(Ⅳ) was reduced to Ce(Ⅲ) after the interaction of the three NPs with duckweed, but the degree of biotransformation differed among the treatments. Specifically, the absolute contents of Ce(III) produced of nCeO2@Cs and nCeO2@Al through biotransformation were reduced by 55.5% and 83.5%, respectively, compared with that of the nCeO2 group, which might be the key factor for the diminished phytotoxicity of the coated nCeO2 to the duckweed. These findings were valuable for understanding the toxicity of metal-based NPs to aquatic plants and for the synthesis of environmentally friendly nanomaterials. © 2024, The Authors. All rights reserved.

关键词： Nanoparticles

Pressure induced transition from chiral charge order to time-reversal symmetry-breaking superconducting state in Nb-doped CsV3Sb5

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arXiv 2024年

作者： Graham, J.N. Islam, S.S. Sazgari, V. Li, Y. Deng, H. Janka, G. Zhong, Y. Gerguri, O. Král, P. Doll, A. Bialo, I. Chang, J. Salman, Z. Suter, A. Prokscha, T. Yao, Y. Okazaki, K. Luetkens, H. Khasanov, R. Wang, Z. Yin, J.-X. Guguchia, Z. PSI Center for Neutron and Muon Sciences CNM Villigen5232 Switzerland Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement Ministry of Education School of Physics Beijing Institute of Technology Beijing100081 China Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems Beijing Institute of Technology Beijing100081 China Department of Physics Southern University of Science and Technology Guangdong Shenzhen518055 China Institute for Solid States Physics The University of Tokyo Kashiwa Japan Physik-Institut Universität Zürich Winterthurerstrasse 190 ZürichCH-8057 Switzerland AGH University of Science and Technology Faculty of Physics and Applied Computer Science Kraków30-059 Poland International Center for Quantum Materials Beijing Institute of Technology Zhuhai319000 China Trans-scale Quantum Science Institute The University of Tokyo Tokyo Japan Material Innovation Research Center The University of Tokyo Kashiwa Japan

The experimental realisation of unconventional superconductivity and charge order in kagome systems AV3Sb5 is of critical importance. We conducted a highly systematic study of Cs(V1−xNbx)3Sb5 with x=0.07 (Nb0.07-CVS) by employing a unique combination of tuning parameters such as doping, hydrostatic pressure, magnetic fields, and depth, using muon spin rotation, AC susceptibility, and STM. We uncovered tunable magnetism in the normal state of Nb0.07-CVS, which transitions to a time-reversal symmetry (TRS) breaking superconducting state under pressure. Specifically, our findings reveal that the bulk of Nb0.07-CVS (at depths >20 nm from the surface) experiences TRS breaking below T∗ = 40 K, lower than the charge order onset temperature, TCO = 58 K. However, near the surface ( © 2024, CC BY.

关键词： Magnetic susceptibility

Probing angle dependent thermal conductivity in twisted bilayer MoSe2

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arXiv 2023年

作者： Mandal, Manab Maity, Nikhilesh Barman, Prahalad Kanti Srivastava, Ashutosh Singh, Abhishek K. Nayak, Pramoda K. Sethupathi, Kanikrishnan Low temperature physics lab Department of Physics Indian Institute of Technology Madras Chennai600 036 India Department of Physics Indian Institute of Technology Madras Chennai600 036 India Materials Research Centre Indian Institute of Science Bangalore560012 India Jain Global Campus Kanakapura Bangalore562112 India

Twisted bilayer (t-BL) transition metal dichalcogenides (TMDCs) attracted considerable attention in recent years due to their distinctive electronic properties, which arise due to the moiré superlattices that lead to the emergence of flat bands and correlated electron phenomena. Also, these materials can exhibit interesting thermal properties, including a reduction in thermal conductivity. In this article, we report the thermal conductivity of monolayer (1L) and t-BL MoSe2 at some specific twist angles around two symmetric stacking AB (0°) and AB ́ (60°) and one intermediate angle (31°) using the optothermal Raman technique. The observed thermal conductivity values are found to be 13 ± 1, 23 ± 3, and 30 ± 4 W m-1K-1 for twist angle [θ] = 58°, 31°and, 3° respectively, which is well supported by our first-principles calculation results. The reduction in thermal conductivity in t-BL MoSe2 compared to monolayer (38 ± 4 W m-1K-1) can be explained by the occurrence of phonon scattering caused by the formation of a moiré superlattice. Herein, the emergence of multiple folded phonon branches and modification in the Brillouin zone caused by in-plane rotation are also accountable for the decrease in thermal conductivity observed in t-BL MoSe2. The theoretical phonon lifetime study and electron localization function (ELF) analysis further reveals the origin of angle-dependent thermal conductivity in t-BL MoSe2. This work paves the way towards tuning the angle-dependent thermal conductivity for any bilayer TMDCs system. Copyright © 2023, The Authors. All rights reserved.

关键词： Density functional theory

Large Nernst Effect in a layered metallic antiferromagnet EuAl2Si2

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arXiv 2024年

作者： Yang, Kunya Xia, Wei Mi, Xinrun Zhang, Yiyue Zhang, Long Wang, Aifeng Chai, Yisheng Zhou, Xiaoyuan Guo, Yanfeng He, Mingquan Low Temperature Physics Lab College of Physics Center of Quantum Materials and Devices Chongqing University Chongqing401331 China Department of Physics Chongqing Three Gorges University Chongqing404100 China School of Physical Science and Technology ShanghaiTech University Shanghai201210 China ShanghaiTech Laboratory for Topological Physics Shanghai201210 China

The large Nernst effect is advantageous for developing transverse Nernst thermoelectric generators or Ettingshausen coolers within a single component, avoiding the complexity of electron- and hole-modules in longitudinal Seebeck thermoelectric devices. We report a large Nernst signal reaching 130 µV/K at 8 K and 13 T in the layered metallic antiferromagnet EuAl2Si2. Notably, this large transverse Nernst thermopower is two orders of magnitude greater than its longitudinal counterpart. The Nernst coefficient peaks around 4 K and 8 K at 3 T and 13 T, respectively. At similar temperatures, both the Hall coefficient and the Seebeck signal change sign. Additionally, nearly compensated electron- and hole-like carriers with high mobility (∼ 4000 cm2/Vs at 4 K) are revealed from the magnetoconductivity. These findings suggest that the large Nernst effect and vanishing Seebeck thermopower in EuAl2Si2 are due to the compensated electron- and hole-like bands, along with the high mobility of the Weyl band near the Fermi level. Our results underscore the importance of band compensation and topological fermiology in achieving large Nernst thermopower and exploring potential Nernst thermoelectric applications at low temperatures. © 2024, CC BY-NC-SA.

关键词： Thermoelectric power

Design and Sensitivity Analysis of an Electro-Optical System for a Ka-Band Traveling Wave Tube

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Design and Sensitivity Analysis of an Electro-Optical System...

International Conference on Infrared and Millimeter Waves

作者： Duo Xu Hexin Wang Tenglong He Weihao Li Shaomeng Wang Zhanliang Wang Yubin Gong National Key Lab of Science and Technology on Vacuum Electronics University of Electronic Science and Technology of China Chengdu Sichuan China School of Automation Beijing Institute of Technology Beijing China

A pencil beam electro-optical system (EOS) for a Ka-band traveling wave tube is designed in this paper. The operating voltage and current of the electron gun are 12060 V and 0.102 A, respectively. A periodic permanent magnet (PPM) beam focusing system is designed to focus the beam and ensure a good beam transparency. The particle tracking simulation results show the beam transparency is 100% in a beam tunnel with a radius of 0.45 mm. The sensitivity of the designed EOS is investigated by varying the density and the position of the magnetic field. The simulation results show that the designed EOS can keep a beam transparency higher than 93% with slight fabrication errors.

关键词： Particle beams Sensitivity analysis Traveling wave tubes Simulation Earth Observing System Focusing Voltage