Production of the X(4014)as the Spin-2 Partner of X(3872)in e^(+)e^(-)Collisions

In 2021,the Belle collaboration reported the first observation of a new structure in theψ(2S)γfinal state produced in the two-photon fusion process.In the hadronic molecule picture,this new structure can be associatedwith the shallow isoscalar D*D* bound state and as such is an excellent candidate for the spin-2 partner of the X(3872)with the quantum numbers J^(PC)=2^(++)conventionally named X_(2).

Vortex Quantum Droplets under Competing Nonlinearities

This concise review summarizes recent advancements in theoretical studies of vortex quantum droplets(VQDs)in matter-wave fields.These are robust self-trapped vortical states in two-and three-dimensional(2D and 3D)Bose–Einstein condensates(BECs)with intrinsic nonlinearity.Stability of VQDs is provided by additional nonlinearities resulting from quantum fluctuations around mean-field states,often referred to as the Lee–Huang–Yang(LHY)corrections.The basic models are presented,with emphasis on the interplay between the mean-field nonlinearity,LHY correction,and spatial dimension,which determines the structure and stability of VQDs.We embark by delineating fundamental properties of VQDs in the 3D free space,followed by consideration of their counterparts in the 2D setting.Additionally,we address stabilization of matter-wave VQDs by optical potentials.Finally,we summarize results for the study of VQDs in the single-component BEC of atoms carrying magnetic moments.In that case,the anisotropy of the long-range dipole-dipole interactions endows the VQDs with unique characteristics.The results produced by the theoretical studies in this area directly propose experiments for the observation of novel physical effects in the realm of quantum matter,and suggest potential applications to the design of new schemes for processing classical and quantum information.

Non-Hermitian CHSH^(*)Game with a Single Trapped-Ion Qubit

The Clauser-Horne-Shimony-Holt(CHSH)game provides a captivating illustration of the advantages of quantum strategies over classical ones.In a recent study,a variant of the CHSH game leveraging a single qubit system,referred to as the CHSH^(*)game,has been identified.We demonstrate that this mapping relationship between these two games remains effective even for a non-unitary gate.Here we delve into the breach of Tsirelson’s bound in a non-Hermitian system,predicting changes in the upper and lower bounds of the player’s winning probability when employing quantum strategies in a single dissipative qubit system.We experimentally explore the impact of the CHSH^(*)game on the player’s winning probability in a single trapped-ion dissipative system,demonstrating a violation of Tsirelson’s bound under the influence of parity-time(PT)symmetry.These results contribute to a deeper understanding of the influence of non-Hermitian systems on quantum games and the behavior of quantum systems under PT symmetry,which is crucial for designing more robust and efficient quantum protocols.

Nonresonant Multiphoton Ionization of Stark Decelerated Molecules by Femtosecond Laser Pulses

Nonresonant multiphoton ionization by femtosecond laser pulses can be applied to any molecule virtually,thereby greatly enhancing the scope of Stark decelerated molecules.For comparison,we detect decelerated and trapped ammonia molecules using two different schemes:(ⅰ) nonresonant multiphoton ionization using intense femtosecond(fs) pulses in the near infrared,and(ⅱ) resonance-enhanced multiphoton ionization using nanosecond(ns) pulses from a tunable UV laser.The observed number of ions per shot for both schemes is similar.The fs laser detection scheme suffers from an increased background,which can be effectively eliminated by subsequent mass and velocity selection.To determine the detection volume of the ns laser detection scheme,we present measurements in which the decelerated ammonia molecules are bunched to a packet with a longitudinal spread well below~100 μm.It is concluded that the detection volume for the ns laser detection scheme is 1.5-2 times larger than that of the fs laser detection scheme.

Vector Spatiotemporal Solitons and Their Memory Features in Cold Rydberg Gases

We propose a scheme to generate stable vector spatiotemporal solitons through a Rydberg electromagnetically induced transparency(Rydberg-EIT)system.Three-dimensional vector monopole and vortex solitons have been found under three nonlocal degrees.The numerical calculation and analytical solutions indicate that these solitons are generated with low energy and can stably propagate along the axes.The behavior of vector spatiotemporal solitons can be manipulated by the local and nonlocal nonlinearities.The results show a memory feature as these solitons can be stored and retrieved effectively by tuning the control field.

Quantum Oscillations in Noncentrosymmetric Weyl Semimetal SmAlSi

As a new type of quantum state of matter hosting low energy relativistic quasiparticles,Weyl semimetals(WSMs)have attracted significant attention for scientific community and potential quantum device applications.In this study,we present a comprehensive investigation of the structural,magnetic,and transport properties of noncentrosymmetric RAl Si(R=Sm,Ce),which have been predicted to be new magnetic WSM candidates.Both samples exhibit nonsaturated magnetoresistance,with about 900%and 80%for Sm Al Si and Ce Al Si,respectively,at temperature of 1.8 K and magnetic field of 9 T.The carrier densities of Sm Al Si and Ce Al Si exhibit remarkable change around magnetic transition temperatures,signifying that the electronic states are sensitive to the magnetic ordering of rare-earth elements.At low temperatures,Sm Al Si reveals prominent Shubnikov–de Haas oscillations associated with the nontrivial Berry phase.High-pressure experiments demonstrate that the magnetic order is robust and survival under high pressure.Our results would yield valuable insights into WSM physics and potentials in applications to next-generation spintronic devices in the RAl Si(R=Sm,Ce)family.

Transverse Rutherford Scattering of Electron-Ion Collision in a Uniformly Magnetized Plasma

Rutherford scattering formula plays an important role in plasma classical transport.It is urgent to investigate influence of magnetic field on the Rutherford scattering since the high magnetic field has been widely used in nowadays magnetic confinement fusion,inertial confinement fusion,and magneto-inertial fusion.In order to elucidate the magnetic field effect in a concise manner,we study the electron-ion collisions transverse to the magnetic field.The scattering angle is defined using the directions of electron velocity before and after collision,which is obtained analytically.It is found that the scattering angle can be influenced by finite magnetic field significantly.The theoretical results agree well with numerical calculation by checking the dependence of scattering angle on the magnetic field.

Recent Progress in Presodiation Technique for High-Performance Na-Ion Batteries

Na-ion batteries(NIBs) have been attracting growing interests in recent years with the increasing demand of energy storage owing to their dependence on more abundant Na than Li. The exploration of the industrialization of NIBs is also on the march, where some challenges are still limiting its step. For instance, the relatively low initial Coulombic efficiency(ICE) of anode can cause undesired energy density loss in the full cell. In addition to the strategies from the sight of materials design that to improve the capacity and ICE of electrodes, presodiation technique is another important method to efficiently offset the irreversible capacity and enhance the energy density. Meanwhile, the slow release of the extra Na during the cycling is able to improve the cycling stability.In this review, we would like to provide a general insight of presodiation technique for high-performance NIBs.The recent research progress including the principles and strategies of presodiation will be introduced, and some remaining challenges as well as our perspectives will be discussed. This review aims to exhibit the basic knowledge of presodiation to inspire the researchers for future studies.

Production of ^(87)Rb Bose-Einstein Condensate in an Asymmetric Crossed Optical Dipole Trap

We report the production of ^(87)Rb Bose–Einstein condensate in an asymmetric crossed optical dipole trap(ACODT)without the need of an additional dimple laser.In our experiment,the ACODT is formed by two laser beams with different radii to achieve efficient capture and rapid evaporation of laser cooled atoms.Compared to the cooling procedure in a magnetic trap,the atoms are firstly laser cooled and then directly loaded into an ACODT without the pre-evaporative cooling process.In order to determine the optimal parameters for evaporation cooling,we optimize the power ratio of the two beams and the evaporation time to maximize the final atom number left in the ACODT.By loading about 6×10^(5) laser cooled atoms in the ACODT,we obtain a pure Bose–Einstein condensate with about 1.4×10^(4) atoms after 19 s evaporation.Additionally,we demonstrate that the fringe-type noises in optical density distributions can be reduced via principal component analysis,which correspondingly improves the reliability of temperature measurement.

Entirety of Quantum Uncertainty and Its Experimental Verification

As a foundation of quantum physics,uncertainty relations describe ultimate limit for the measurement uncertainty of incompatible observables.Traditionally,uncertainty relations are formulated by mathematical bounds for a specific state.Here we present a method for geometrically characterizing uncertainty relations as an entire area of variances of the observables,ranging over all possible input states.We find that for the pair of position and momentum operators,Heisenberg's uncertainty principle points exactly to the attainable area of the variances of position and momentum.Moreover,for finite-dimensional systems,we prove that the corresponding area is necessarily semialgebraic;in other words,this set can be represented via finite polynomial equations and inequalities,or any finite union of such sets.In particular,we give the analytical characterization of the areas of variances of(a)a pair of one-qubit observables and(b)a pair of projective observables for arbitrary dimension,and give the first experimental observation of such areas in a photonic system.

Production of Degenerate Fermi Gases of ~6Li Atoms in an Optical Dipole Trap

We report the experimental production of degenerate Fermi gases of 6 Li atoms in an optical dipole trap.The gray-molasses technique is carried out to decrease the atomic temperature to 57 μK,which facilitates the efficient loading of cold atoms into the optical dipole trap.The Fermi degeneracy is achieved by evaporative cooling of a two-spin mixture of ~6 Li atoms on the Feshbach resonance.The degenerate atom number per spin is 3.5×10^(4),and the reduced temperature T/T_F is as low as 0.1,where T_F is the Fermi temperature of the non-interacting Fermi gas.We also observe the anisotropic expansion of the atom cloud in the strongly interacting regime.

Stable Compositions, Structures and Electronic Properties in K–Ga Systems Under Pressure

New stable stoichiometries in K-Ga systems are firstly investigated up to 100 GPa by the unbiased structure searching techniques.Six novel compositions as K4Ga,K3Ga,K2Ga,KGa,KGa2 and KGa4 are found to be thermodynamically stable under pressure.Most of the predicted stable phases exhibit metallic character,while the Fd3m KGa phase behaves as a semiconductor with a bandgap ~1.62 eV.Notably,the gallium atoms exhibit different interesting morphologies;e.g.,Ga2 units,zigzag chains,six rings and cage.We further investigate the bonding nature of K-Ga systems with help of electron localization function and Bader charge analyses.Strong covalent bonding characteristics are found between the Ga and Ga atoms,and ionic bonding patterns are observed between the K and Ga atoms.Meanwhile,we notice charge transferring from the K atom to the Ga atom in the K-Ga systems.The present results can be helpful for understanding the diverse structures and properties of K-Ga binary compounds at high pressures.

Physical Properties of Half-Heusler Antiferromagnet MnPtSn Single Crystal

We report the growth of ternary half-Heusler MnPtSn single crystals and detailed study on its structural and physical properties.MnPtSn single crystal has a larger lattice parameter than that in polycrystal and it exhibits antiferromagnetism with transition temperature TN at about 215 K,distinctly different from the ferromagnetism of MnPtSn polycrystal.Hall resistivity measurement indicates that the dominant carriers are hole-type and the nearly temperature-independent carrier concentration reaches about 2.86×10^22 cm^-3 at 5 K.Moreover,the carrier mobility is also rather low(4.7 cm^2·V^-1s^-1 at 5 K).The above results strongly suggest that the significant Mn/Sn anti-site defects,i.e.,the content of Mn in MnPtSn single crystal,play a vital role on structural,magnetic and transport properties.

Mode Structures and Damping of Quantized Spin Waves in Ferromagnetic Nanowires

Magnonic devices based on spin waves are considered as a new generation of energy-efficient and high-speed devices for storage and processing of information.Here we experimentally demonstrate that three distinct dominated magneto-dynamic modes are excited simultaneously and coexist in a transversely magnetized ferromagnetic wire by the ferromagnetic resonance(FMR)technique.Besides the uniform FMR mode,the spin-wave well mode,the backward volume magnetostatic spin-wave mode,and the perpendicular standing spin-wave mode are experimentally observed and further confirmed with more detailed spatial profiles by micromagnetic simulation.Furthermore,our experimental approach can also access and reveal damping coefficients of these spin-wave modes,which provides essential information for development of magnonic devices in the future.

Coaxial Multi-Wavelength Generation in YVO4 Crystal with Stimulated Raman Scattering Excited by a Picosecond-Pulsed 1064 Laser

The multiwavelength characteristics of stimulated Raman scattering(SRS)in YVO4 crystal excited by a picosecond laser at 1064nm are investigated theoretically and experimentally.Laser output with seven wavelengths is achieved coaxially and synchronously at 894,972,1175,1312,1486,1713 and 2022 nm in a YVO4 crystal.The maximum total Raman output energy is as high as 2.77mJ under the pump energy of 7.75mJ.A maximum total Raman conversion efficiency of 47.8%is obtained when the pump energy is 6.54 mj.This is the highest order of Stokes components and the highest output energy generated by YVO4 reported up to date.This work expands the Raman spectrum of YVO4 crystal to the near-IR regime,with seven wavelengths covered at the same time,paving the way for new wavelength generation in the near-IR regime and its multiwavelength application.

Effects of Total-Ionizing-Dose Irradiation on Single-Event Burnout for Commercial Enhancement-Mode AlGaN/GaN High-Electron Mobility Transistors

We investigate the synergism effect of total ionizing dose(TID)on single-event burnout(SEB)for commercial enhancement-mode AlGaN/GaN high-electron mobility transistors.Our experimental results show that the slight degradation of devices caused by gamma rays can affect the stability of the devices during the impact of high energy particles.During heavy ion irradiation,the safe working values of drain voltage are significantly reduced for devices which have already been irradiated by 60Co gamma rays before.This could be attributed to more charges trapped caused by 60Co gamma rays,which make GaN devices more vulnerable to SEB.Moreover,the electrical parameters of GaN devices after 60Co gamma and heavy-ion irradiations are presented,such as the output characteristic curve,effective threshold voltages,and leakage current of drain.These results demonstrate that the synergistic effect of TID on SEB for GaN power devices does in fact exist.

Performance Analyses of Planar Schottky Barrier MOSFETs with Dual Silicide Layers at Source/Drain on Bulk Substrates and Material Studies of ErSi_x/CoSi_2/Si Stack Interface

A dual silicide layer structure is proposed for Schottky barrier metal-oxide-semiconductor held effect transistors(MOSFETs)on bulk substrates.The source/drain regions are designed to be composed with dual stacked silicide layers,forming different barrier heights to silicon channel.Performance comparisons between the dual barrier structure and the single barrier structure are carried out with numerical simulations.It is found that the dual barrier structure has significant advantages over the single barrier structure because the drive current and leakage current of the dual barrier structure can be modulated.Furthermore,the dual barrier structure's performance is nearly insensitive to the total silicide thickness,which can relax the fabrication requirements and even make an SOI substrate unnecessary for planar device design.The formation of ErSix/CoSi2 stacked multilayers has been proved by experiments.

Machine Learning to Instruct Single Crystal Growth by Flux Method

Growth of high-quality single crystals is of great significance for research of condensed matter physics. The exploration of suitable growing conditions for single crystals is expensive and time-consuming, especially for ternary compounds because of the lack of ternary phase diagram. Here we use machine learning(ML) trained on our experimental data to predict and instruct the growth. Four kinds of ML methods, including support vector machine(SVM), decision tree, random forest and gradient boosting decision tree, are adopted. The SVM method is relatively stable and works well, with an accuracy of 81% in predicting experimental results. By comparison,the accuracy of laboratory reaches 36%. The decision tree model is also used to reveal which features will take critical roles in growing processes.

Charge Transport Properties of the Majorana Zero Mode Induced Noncollinear Spin Selective Andreev Reflection

We study the charge transport properties of the spin-selective Andreev reflection(SSAR)effect between a spin polarized scanning tunneling microscope(STM)tip and a Majorana zero mode(MZM).Considering both the MZM and the excited states,we calculate the conductance and the shot noise power of the noncollinear SSAR using scattering theory.We find that the excited states give rise to inside peaks.Moreover,we numerically calculate the shot noise power and the Fano factor of the SSAR effect.Our calculation shows that the shot noise power and the Fano factor are related to the angle between the spin polarization direction of the STM tip and that of the MZM,which provide additional characteristics to detect the MZM via SSAR.

Landau–Zener–Stückelberg Interference in Nonlinear Regime

Landau-Zener-Stückelberg(LZS)interference has drawn renewed attention to quantum information processing research because it is not only an effective tool for characterizing two-level quantum systems but also a powerful approach to manipulate quantum states.Superconducting quantum circuits,due to their versatile tunability and degrees of control,are ideal platforms for studying LZS interference phenomena.We use a superconducting Xmon qubit to study LZS interference by parametrically modulating the qubit transition frequency nonlinearly.For dc flux biasing of the qubit slightly far away from the optimal flux point,the qubit excited state population shows an interference pattern that is very similar to the standard LZS interference in linear regime,except that all bands shift towards lower frequencies when increasing the rf modulation amplitude.For dc flux biasing close to the optimal flux point,the negative sidebands and the positive sidebands behave differently,resulting in an asymmetric interference pattern.The experimental results are also in good agreement with our analytical and numerical simulations.