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Nonlocal coherence harvesting from quantum vacuum

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Communications in Theoretical physics 2024年第07期76卷 46-53页

作者： Rui-Di Wang Shu-Min Wu Xiao-Li Huang department of physics Liaoning Normal University

It is well known that nonlocal coherence reflects nonclassical correlations better than quantum entanglement. Here, we analyze nonlocal coherence harvesting from the quantum vacuum to particle detectors adiabatically interacting with a quantum scalar field in Minkowski *** find that the harvesting-achievable separation range of nonlocal coherence is larger than that of quantum entanglement. As the energy gap grows sufficiently large, the detectors harvest less quantum coherence, while the detectors could extract more quantum entanglement from the vacuum state. Compared with the linear configuration and the scalene configuration, we should choose the model of equilateral triangle configuration to harvest tripartite coherence from the vacuum. Finally, we find a monogamous relationship, which means that tripartite l1-norm of coherence is essentially bipartite types.

关键词： monogamous relationship nonlocal coherence quantum vacuum

Two-dimensional investigation of characteristic parameters and their gradients for the self-generated electric and magnetic fields of laser-induced zirconium plasma

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Plasma Science and Technology 2024年第5期26卷 138-155页

作者： Tayyaba SAJID Shazia BASHIR Mahreen AKRAM Maira RAZZAQ Khaliq MAHMOOD Centre for Advanced Studies in physics Institute of PhysicsGovernment College University LahoreLahore 54000Pakistan department of physics Institute of PhysicsGovernment College University LahoreLahore 54000Pakistan

Two-dimensional diagnosis of laser-induced zirconium(Zr)plasma has been experimentally performed using the time-of-flight method by employing Faraday cups in addition to electric and magnetic *** characteristic parameters of laser-induced Zr plasma have been evaluated as a function of different laser irradiances ranging from 4.5 to 11.7 GW cm-2 at different axial positions of 1–4 cm with a fixed radial distance of 2 cm.A well-supporting correlation between the plume parameters and the laser-plasma-produced spontaneous electric and magnetic(E and B)fields was *** measurements of the characteristic parameters and spontaneously induced fields were observed to have an increasing trend with the increasing laser ***,when increasing the spatial distance in both the axial and radial directions,the plasma parameters(electron/ion number density,temperature and kinetic energy)did not show either continuously increasing or decreasing trends due to various kinetic and dynamic processes during the spatial evolution of the ***,the E and B fields were observed to be always diffusing away from the *** radial component of electron number densities remained higher than the axial number density component,whereas the axial ion number density at all laser irradiances and axial distances remained higher than the radial ion number *** higher axial self-generated electric field(SGEF)values than radial SGEF values are correlated with the effective charge-separation mechanism of electrons and *** generation of a self-generated magnetic field is observed dominantly in the radial direction at increasing laser irradiance as compared to the axial one due to the deflection of fast-moving electrons and the persistence of two-electron temperature on the radial axis.

关键词： Faraday cup axial and radial expansion space-charge effect laser-induced zirconium plasma two-electron temperature distribution self-generated electric and magnetic fields

Free Energy of Anisotropic Strangeon Stars

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Research in astronomy and Astrophysics 2024年第2期24卷 50-57页

作者： Shichuan Chen Yong Gao Enping Zhou Renxin Xu department of astronomy School of PhysicsPeking UniversityBeijing 100871China Kavli Institute for astronomy and Astrophysics Peking UniversityBeijing 100871China department of astronomy School of PhysicsHuazhong University of Science and TechnologyWuhan 430074China

Can pulsar-like compact objects release further huge free energy besides the kinematic energy of rotation?This is actually relevant to the equation of state of cold supra-nuclear matter,which is still under hot *** energy is surely needed to understand various observations,such asγ-ray bursts,fast radio bursts and softγ-ray *** this paper,the elastic/gravitational free energy of solid strangeon stars is revisited for strangeon stars,with two anisotropic models to calculate in general *** is found that huge free energy(>10^(46)erg)could be released via starquakes,given an extremely small anisotropy((p_(t)-p_(r))/p_(r)~10^(-4),with pt/pr the tangential/radial pressure),implying that pulsar-like stars could have great potential of free energy release without extremely strong magnetic fields in the solid strangeon star model.

关键词： (stars:)pulsars general-methods numerical-(stars:)gamma-ray bursts general

Significantly enhanced superconductivity in monolayer FeSe films on SrTiO3（001） via metallic δ-doping

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National Science Review 2024年第3期11卷 119-127页

作者： Xiaotong Jiao Wenfeng Dong Mingxia Shi Heng Wang Cui Ding Zhongxu Wei Guanming Gong Yanan Li Yuanzhao Li Binjie Zuo Jian Wang Ding Zhang Minghu Pan Lili Wang Qi-Kun Xue State Key Laboratory of Low-Dimensional Quantum physics Department of Physics Tsinghua University School of physics&Information Technology Shaanxi Normal University Beijing Academy of Quantum Information Sciences department of physics Southern University of Science and Technology International Center for Quantum Materials School of Physics Peking University department of physics The Pennsylvania State University Collaborative Innovation Center of Quantum Matter Hefei National Laboratory

Superconductivity transition temperature（Tc） marks the inception of a macroscopic quantum phase-coherent paired state in fermionic systems. For 2D superconductivity, the paired electrons condense into a coherent superfluid state at Tc, which is usually lower than the pairing temperature, between which intrinsic physics including Berezinskii–Kosterlitz–Thouless transition and pseudogap state are hotly debated. In the case of monolayer FeSe superconducting films on SrTiO3（001）, although the pairing temperature（Tp） is revealed to be 65–83 K by using spectroscopy characterization, the measured zero-resistance temperature（Tc0） is limited to 20 K. Here, we report significantly enhanced superconductivity in monolayer FeSe films by δ-doping of Eu or Al on SrTiO3（001） surface, in which Tc0is enhanced by 12 K with a narrowed transition width ΔTc～8 K, compared with non-doped samples. Using scanning tunneling microscopy/spectroscopy measurements, we demonstrate lowered work function of the δ-doped SrTiO3（001） surface and enlarged superconducting gaps in the monolayer FeSe with improved morphology/electronic homogeneity. Our work provides a practical route to enhance 2D superconductivity by using interface engineering.

关键词： monolayer FeSe interface superconductivity δ-doping zero-resistance temperature superconductivity transition temperature

Nonlinearly induced entanglement in dissipatively coupled optomechanical system

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Chinese physics B 2024年第6期33卷 255-260页

作者：杨文全冷轩程泂张闻钊 department of physics Ningbo UniversityNingbo 315211China

Nonlinearly induced steady-state photon–phonon entanglement of a dissipative coupled system is studied in the bistable regime. Quantum dynamical characteristics are analysed by solving the mean-field and fluctuation equations of the system. It is shown that dissipative coupling can induce bistable behaviour for the effective dissipation of the *** suitable parameters, one of the steady states significantly reduces the dissipative effect of the system. Consequently,a larger steady-state entanglement can be achieved compared to linear dynamics. Furthermore, the experimental feasibility of the parameters is analysed. Our results provide a new perspective for the implementation of steady-state optomechanical entanglement.

关键词： entanglement optomechanical system dissipatively coupling

Interacting topological magnons in a checkerboard ferromagnet

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Chinese physics B 2024年第3期33卷 596-601页

作者：朱恒施洪潮唐政国唐炳 department of physics Jishou UniversityJishou 416000China

This work is devoted to studying the magnon-magnon interaction effect in a two-dimensional checkerboard ferromagnet with the Dzyaloshinskii-Moriya *** a first-order Green function method,we analyze the influence of magnon-magnon interaction on the magnon band *** find that Chern numbers of two renormalized magnon bands are different above and below the critical temperature,which means that the magnon band gap-closing phenomenon is an indicator for one topological phase transition of the checkerboard *** results show that the checkerboard ferromagnet possesses two topological phases,and its topological phase can be controlled either via the temperature or the applied magnetic field due to magnon-magnon ***,it is found that the topological phase transition can occur twice with the increase in the temperature,which is different from the results of the honeycomb ferromagnet.

关键词： topological magnons magnon-magnon interactions topological phase transitions checkerboard ferromagnets

MEMS-actuated terahertz metamaterials driven by phase-transition materials

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Frontiers of Optoelectronics 2024年第2期17卷 23-32页

作者： Zhixiang Huang Weipeng Wu Eric Herrmann Ke Ma Zizwe A.Chase Thomas A.Searles M.Benjamin Jungfleisch Xi Wang department of Materials Science and Engineering College of EngineeringUniversity of DelawareNewarkDE 19716USA department of physics and astronomy College of Arts and SciencesUniversity of DelawareNewarkDE 19716USA department of Electrical and Computer Engineering College of EngineeringUniversity of Illinois ChicagoChicagoIL 60607USA

The non-ionizing and penetrative characteristics of terahertz(THz)radiation have recently led to its adoption across a variety of *** effectively utilize THz radiation,modulators with precise control are *** most recent THz modulators manipulate the amplitude,frequency,or phase of incident THz radiation,considerably less progress has been made toward THz polarization *** methods for polarization control suffer from high driving voltages,restricted modulation depth,and narrow band capabilities,which hinder device performance and broader ***,an ideal THz modulator that offers high modulation depth along with ease of processing and operation is *** this paper,we propose and realize a THz metamaterial comprised of microelectromechanical systems(MEMS)actuated by the phase-transition material vanadium dioxide(VO_(2)).Simulation and experimental results of the three-dimensional metamaterials show that by leveraging the unique phase-transition attributes of VO_(2),our THz polarization modulator offers notable advancements over existing designs,including broad operation spectrum,high modulation depth,ease of fabrication,ease of operation condition,and continuous modulation *** enhanced features make the system a viable candidate for a range of THz applications,including telecommunications,imaging,and radar systems.

关键词： Metamaterials MEMS THz VO_(2) Phase-transition material

Neutral and metallic *** and semiconducting surface layer in acceptor doped CeO_(2)

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 795-802页

作者： Ilan Riess physics department Technion IITHaifa 3200003Israel

The monomolecular surface layer of acceptor doped CeO_(2) may become neutral and metallic or charged and *** is revealed in the theoretical analysis of the oxygen pressure dependence of the surface defects concentration in acceptor doped ceria with two different dopant types and operated under different oxygen *** published experimental data for highly reduced Sm0.2Ce0.8O1.9-x(SDC)containing a fixed valence dopant Sm3+are very different from those published for Pr0.1Ce0.9O_(2)-x(PCO) with the variable valence dopant Pr4+/Pr3+being reduced under milder *** theoretical analysis of these experimental results fits very well the experimental results of SDC and *** leads to the following predictions:the highly reduced surface of SDC is metallic and neutral,the metallic surface electron density of state is gs=0.9×10^(38)J-1·m^(-2)(1.4×1015eV^(-1)·cm^(-2)),the electron effective mass is meff,s=3.3me,and the phase diagram of the reduced surface has theα(fcc)structure as in the *** PCO a double layer is predicted to be formed between the surface and the bulk with the surface being negatively charged and *** surface of PCO maintains high Pr^(3+) defect concentration as well as relative high oxygen vacancy concentration at oxygen pressures higher than in the *** reasons for the difference between a metallic and semiconducting surface layer of acceptor doped CeO_(2) are reviewed,as well as the key theoretical considerations applied in coping with this *** that we make use of the experimental data and theoretical analysis available for acceptor doped ceria.

关键词： CeO_(2) surface defects metallic surface oxide reduction Sm doped CeO_(2) Pr doped CeO_(2)

Structural,optical,electrical,and dielectric relaxation properties of rare earth containing sodium bismuth titanate Na_(0.5)Bi_(0.5)TiO_(3) perovskite:Effect of ionic radius

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Journal of Rare Earths 2024年第2期42卷 383-391,I0006页

作者： Rajdip Roy Abhigyan Dutta department of physics The University of BurdwanBurdwan713104India

The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE^(3+)(RE=La,Sm,Dy,and Ho) on structural and various physical properties of sodium bismuth titanate(Na_(0.5)B_(0.5)TiO_(3),NBT) based perovskite *** X-ray diffraction data indicate the successful formation of the rhombohedral phase(space group R3c) of NBT nano perovskite incorporated with various rare earth ions in *** lattice parameters were found to increase linearly with the ionic radius of the dopant *** ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared *** grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic *** emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and *** UV-Vis spectra reveal that La-doped NBT composition exhibits the lowest optical band gap,which unfolds the application of NBT-based perovskite as photoactive *** ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius,i.e.,La-doped NBT compound,exhibits the highest dc and bulk conductivity with the lowest activation *** frequency-dependent dielectric data follows Havriliak-Negami(HN) formalism and non-Debye type relaxation *** also indicate that La-doped NBT composition exhibits the highest dielectric strength ***,this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the Bi-site of NBT perovskite improves its microstructural,optical,and electrical properties.

关键词： Rare earth doped NBT Microstructural analysis Optical band gap AC Conductivity Dielectric relaxation Rare earths