Chin. Phys. B

The application of quantum coherence as a resource

Si-Yuan Liu(刘思远) and Heng Fan(范桁)

Chin. Phys. B, 2023, 32 (11): 110304. DOI: 10.1088/1674-1056/acfa85

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Quantum coherence is a basic concept in quantum mechanics, representing one of the most fundamental characteristics that distinguishes quantum mechanics from classical physics. Quantum coherence is the basis for multi-particle interference and quantum entanglement. It is also the essential ingredient for various physical phenomena in quantum optics, quantum information, etc. In recent years, with the proposal of a quantum coherence measurement scheme based on a resource theory framework, quantum coherence as a quantum resource has been extensively investigated. This article reviews the resource theories of quantum coherence and introduces the important applications of quantum coherence in quantum computing, quantum information, and interdisciplinary fields, particularly in quantum thermodynamics and quantum biology. Quantum coherence and its applications are still being explored and developed. We hope this review can provide inspiration for relevant research.

Special breathing structures induced by bright solitons collision in a binary dipolar Bose-Einstein condensates

Gen Zhang(张根), Li-Zheng Lv(吕李政), Peng Gao(高鹏), and Zhan-Ying Yang(杨战营)

Chin. Phys. B, 2023, 32 (11): 110303. DOI: 10.1088/1674-1056/acf283

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We numerically investigate the breathing dynamics induced by collision between bright solitons in a binary dipolar Bose-Einstein condensates, whose dipole-dipole interaction and contact interaction are attractive. We identify three special breathing structures, such as snakelike special breathing structure, mixed breathing structure, and divide breathing structure. The characteristics of these breathing structures can be described by breathing frequency Ω, maximum breathing amplitude A and lifetime τ, which can be manipulated by atomic number N_i and interspecies scattering length a₁₂. Meanwhile, the above breathing structures can realize the process of quasi-transition with a reasonable N_i and a₁₂. Additionally, the collision of two special breathing structures also can bring more abundant breathing dynamics. Our results provide a reference for the study of soliton interactions and deepen the understanding of soliton properties in a binary dipolar Bose-Einstein condensates.

Low-lying electronic states of osmium monoxide OsO

Wen Yan(严汶) and Wenli Zou(邹文利)

Chin. Phys. B, 2023, 32 (11): 113101. DOI: 10.1088/1674-1056/acec46

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The ground state of osmium monoxide (OsO) has long been controversial. In this paper, the low-lying Λ-S and Ω electronic states of OsO have been comprehensively studied by the high-precision multi-reference calculations. The ground state of OsO is unexpectedly the closed-shell ¹Σ+ state with a double bond instead of the previously reported ³Φ or ⁵Σ⁺ state; after including the spin-orbit coupling effects, the ground state becomes ³Π₂. With the help of the theoretical spectroscopic constants and transition dipole moments, the emission spectra in the region of 405 nm-875 nm are assigned. Our results will facilitate the future studies of absorption and emission spectra of OsO.

Vector fiber Bragg gratings accelerometer based on silicone compliant cylinder for low frequency vibration monitoring

Wenyu Hu(胡文玉), Zhuo Chen(陈卓), Jiangshan You(尤江山), Ruohui Wang(王若晖), Rui Zhou(周锐), and Xueguang Qiao(乔学光)

Chin. Phys. B, 2023, 32 (11): 114201. DOI: 10.1088/1674-1056/acec43

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Vector accelerometer has attracted much attention for its great application potential in underground seismic signal measurement. We propose and demonstrate a novel vector accelerometer based on the three fiber Bragg gratings (FBGs) embedded in a silicone rubber compliant cylinder at 120° distributed uniformly. The accelerometer is capable of detecting the orientation of vibration with a range of 0°-360° and the acceleration through monitoring the central wavelength shifts of three FBGs simultaneously. The experimental results show that the natural frequency of the accelerometer is about 85 Hz, and the sensitivity is 84.21 pm/g in the flat range of m 20 Hz-60 Hz. Through experimental calibration, the designed accelerometer can accurately obtain vibration vector information, including vibration orientation and acceleration. In addition, the range of resonant frequency and sensitivity can be expanded by adjusting the hardness of the silicone rubber materials. Due to the characteristics of small size and orientation recognition, the accelerometer can be applied to low-frequency vibration acceleration vector measurement in narrow spaces.

Topological resonators based on hexagonal-star valley photonic crystals

Xin Wan(万鑫), Chenyang Peng(彭晨阳), Gang Li(李港), Junhao Yang(杨俊豪), and Xinyuan Qi(齐新元)

Chin. Phys. B, 2023, 32 (11): 114208. DOI: 10.1088/1674-1056/acf44b

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In valley photonic crystals, topological edge states can be gained by breaking the spatial inversion symmetry without breaking time-reversal symmetry or creating pseudo-spin structures, making highly unidirectional light transmission easy to achieve. This paper presents a novel physical model of a hexagonal-star valley photonic crystal. Simulations based on the finite element method (FEM) are performed to investigate the propagation of TM polarized mode and its application to ring resonators. The results show that such a topologically triangular ring resonator exhibits an optimum quality factor Q of about 1.25× 10⁴, and Q has a maximum value for both frequency and the cavity length L. Our findings are expected to have significant implications for developing topological lasers and wavelength division multiplexers.

High stability and low noise laser-diode end-pumped Nd: YAG ceramic passively Q-switched laser at 1123 nm based on a Ti₃C₂T_x-PVA saturable absorber

Jia-Le Yan(闫佳乐), Ben Li(李奔), Guo-Zhen Wang(王国珍), Shun-Yu Yang(杨顺宇), Bao-Le Lu(陆宝乐), and Yang Bai(白杨)

Chin. Phys. B, 2023, 32 (11): 114212. DOI: 10.1088/1674-1056/acf495

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We report a high repetition frequency, high power stability and low laser noise laser-diode (LD) end-pumped Nd: YAG ceramic passively Q-switched laser at 1123 nm based on a Ti₃C₂T_x-polyvinyl alcohol (PVA) film as a saturable absorber (SA). A Brewster polarizer (BP) and a birefringent crystal (BC) are incorporated to enable frequency selection and filtering for the passively Q-switched 1123 nm pulsed laser to improve the power stability and reduce the noise. When the pump power is 5.1 W, an average output power of 457.9 mW is obtained, corresponding to a repetition frequency of 1.09 MHz, a pulse width of 56 ns, a spectral line width of 0.65 nm, a power instability of ± 0.92%, and a laser noise of 0.89%. The successful implementation of the “Ti₃C₂T_x-PVA film passively Q-switching” combined with “frequency selection and filtering of m BP + BC” technology path provides a valuable reference for developing pulsed laser with high repetition frequency, high stability and low noise.

Topological states switching and group velocity control in two-dimensional non-reciprocal Hermitian photonic lattice

Yu Lin(林宇), Yuandan Wang(王元旦), Junhao Yang(杨俊豪), Yixuan Fu(符艺萱), and Xinyuan Qi(齐新元)

Chin. Phys. B, 2023, 32 (11): 114213. DOI: 10.1088/1674-1056/ad0621

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We proposed a model with non reciprocal coupling coefficients, in which the imaginary parts γ indicate the phase delay or exceed term. The distributions of band structure and the group velocity are both characterized as a function of the coupling. we studied the system's topological states and group velocity control. The results show that the movement and breaking of Dirac points exist in the energy band of the system. By changing the coupling coefficients, the conversion between any topological states corresponds to different Chern number. Topological edge states exist in topological non-trivial systems that correspond to the two different Chern numbers. Besides, it is also found that both the coupling coefficient and the wave vector can cause the oscillation of the pulse group velocity. At the same time, the topological state can suppress the amplitude of the group velocity profiles. Our findings enrich the theory of light wave manipulation in high-dimensional photonic lattices and provide a novel view for realizing linear localization and group velocity regulation of light waves, which has potential application in high-speed optical communication and quantum information fields.

Absorption spectra and enhanced Kerr nonlinearity in a four-level system

Hao-Jie Huangfu(皇甫浩杰), Ying-Jie Du(杜英杰), and Ai-Hua Gao(高爱华)

Chin. Phys. B, 2023, 32 (11): 114214. DOI: 10.1088/1674-1056/ad0622

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In a coherent system, enhanced nonlinearity can be reached via far-detuned coupling fields in the presence of Autler-Townes splitting. We explore the absorption spectra and the Kerr nonlinearity of the coherent system via the interaction between a four-level atomic system and triple fields. We obtain the absorption spectra with double, triple and even quadruple peaks which depend on both the magnitude and the difference of the coupling fields. The Kerr nonlinearity always remains reversely correlated with the absorption spectra. We find that the large coupling detunings can lead to a significant growth of the Kerr nonlinearity and the degenerate four-wave mixing. Both the Kerr nonlinearity and the four-wave mixing can be managed by adjusting the detunings of the coupling fields.

Bacterial turbulence in gradient confinement

Ningzhe Yan(颜宁哲), Chenliang Xie(谢晨亮), Hao Luo(罗昊), Yanan Liu(刘亚楠), and Guangyin Jing(经光银)

Chin. Phys. B, 2023, 32 (11): 114704. DOI: 10.1088/1674-1056/acea6d

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We investigate a novel form of non-uniform living turbulence at an extremely low Reynolds number using a bacterial suspension confined within a sessile droplet. This turbulence differs from homogeneous active turbulences in two or three-dimensional geometries. The heterogeneity arises from a gradient of bacterial activity due to oxygen depletion along the droplet's radial direction. Motile bacteria inject energy at individual scales, resulting in local anisotropic energy fluctuations that collectively give rise to isotropic turbulence. We find that the total kinetic energy and enstrophy decrease as distance from the drop contact line increases, due to the weakening of bacterial activity caused by oxygen depletion. While the balance between kinetic energy and enstrophy establishes a characteristic vortex scale depending on the contact angle of the sessile drop. The energy spectrum exhibits diverse scaling behaviors at large wavenumber, ranging from k^-1/5 to k^-1, depending on the geometric confinement. Our findings demonstrate how spatial regulation of turbulence can be achieved by tuning the activity of driving units, offering insights into the dynamic behavior of living systems and the potential for controlling turbulence through gradient confinements.

Straight and twisted Weyl nodal line phonons in Ho₂CF₂ material

Xin-Yue Kang(康鑫越), Jin-Yang Li(李金洋), and Si Li(李思)

Chin. Phys. B, 2023, 32 (11): 116301. DOI: 10.1088/1674-1056/aceaea

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Based on first-principles calculations, symmetry analysis and model construction, we predict that Ho₂CF₂ hosts both straight and twisted Weyl nodal lines in its bulk phonon spectrum. We identify that the top two phonon bands entangle with each other, forming two straight Weyl nodal lines on the K-H and K'-H' paths at the Brillouin zone (BZ) boundary, and six twisted Weyl nodal lines within the BZ. All the Weyl nodal lines along the k_z direction and across the entire BZ. The symmetry analysis indicates that these Weyl nodal lines are protected by the PT symmetry and crystal symmetry. The Berry phase and drumhead-like nontrivial surface states are calculated. We also construct a tight-binding model to describe these nodal lines. Our work provides an excellent material platform for exploring the fascinating physics associated with straight and twisted Weyl nodal line phonons.

Interfacial photoconductivity effect of type-I and type-II Sb₂Se₃/Si heterojunctions for THz wave modulation

Xue-Qin Cao(曹雪芹), Yuan-Yuan Huang(黄媛媛), Ya-Yan Xi(席亚妍), Zhen Lei(雷珍), Jing Wang(王静), Hao-Nan Liu(刘昊楠), Ming-Jian Shi(史明坚), Tao-Tao Han(韩涛涛), Meng-En Zhang(张蒙恩), and Xin-Long Xu(徐新龙)

Chin. Phys. B, 2023, 32 (11): 116701. DOI: 10.1088/1674-1056/acf301

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An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivity and photocarrier density at the heterojunction interface remains elusive. Herein, we have obtained the photoconductivity and photocarrier density of 173 nm Sb₂Se₃/Si (type-I heterojunction) and 90 nm Sb₂Se₃/Si (type-II heterojunction) utilizing terahertz (THz) time-domain spectroscopy (THz-TDS) and a theoretical Drude model. Since type-I heterojunctions accelerate carrier recombination and type-II heterojunctions accelerate carrier separation, the photoconductivity and photocarrier density of the type-II heterojunction (21.8× 10⁴ S·m^-1, 1.5× 10¹⁵ cm^-3) are higher than those of the type-I heterojunction (11.8× 10⁴ S·m^-1, 0.8× 10¹⁵ cm^-3). These results demonstrate that a type-II heterojunction is superior to a type-I heterojunction for THz wave modulation. This work highlights THz-TDS as an effective tool for studying photoconductivity and photocarrier density at the heterojunction interface. In turn, the intriguing interfacial photoconductivity effect provides a way to improve the THz wave modulation performance.

Photo-responsive droplet manipulation slippery lubricant-infused porous surface with ultra-high durability

Ze-Zhi Liu(刘泽志), Chen Zhang(张琛), Tong Wen(文通), Hui-Zhu Li(李荟竹), Wen-Ping Gao(高文萍), Xin-Kong Wang(王新孔), Wei Zhao(赵伟), Kai-Ge Wang(王凯歌), and Jin-Tao Bai(白晋涛)

Chin. Phys. B, 2023, 32 (11): 116801. DOI: 10.1088/1674-1056/ad0143

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Photo-responsive slippery lubricant-infused porous surface (SLIPS) for droplet manipulation is flexible, non-contact and non-destructive in droplet manipulation, which has promising applications in flexible robotics, microfluidics, biomedicine, and chemical analysis. However, the repeated manipulations for droplets of SLIPSs are quite limited in the works reported so far, the poor durability of droplet manipulation severely limits the practical application of the surfaces. In this paper, an Fe₃O₄-doped polydimethylsiloxane (PDMS)-based SLIPS is proposed and implemented to achieve ultra-high repeated droplet manipulation numbers under near-infrared ray (NIR) laser irradiation. Firstly, a micron columnar array structure with micro-pits on the top side, as well as, a wall structure out of the array is designed on SLIPS to reserve the lubricant. Secondly, the prototype of the SLIPS is fabricated by a 3-step ultraviolet (UV) lithography, and subsequently immersed in silicone oil for more than 96 h to obtain the ultra-high durability slippery lubricant-infused porous surface (UD-SLIPS). With a power of 25 mW-85 mW NIR laser, the repeated manipulation of microdroplets (≤ 5 μ L) in the scale of 1 cm can exceed more than 3000 times which is far beyond that in previous reports. Finally, the droplet manipulation performance of this photo-responsive UD-SLIPS and the influence of infusion time on durability are investigated. The mechanism of the PDMS swelling effect is found to be the key factor in improving the droplet manipulation durability of SLIPS. The findings of this work would be of great significance for the development of highly durable photo-responsive functional surfaces for droplet manipulation.

Structural, electronic and magnetic properties of Fe-doped strontium ruthenates

Nan Liu(刘楠), Xiao-Chao Wang(王晓超), and Liang Si(司良)

Chin. Phys. B, 2023, 32 (11): 117101. DOI: 10.1088/1674-1056/ad0112

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By employing a combined approach of density-functional theory (DFT) and dynamical mean-field theory (DMFT) calculations, we examine the structural, electronic, and magnetic characteristics of two distinct strontium ruthenates: Sr₂RuO₄, an unconventional superconductor, and the correlated metal SrRuO₃, both at 50% Fe-doping level. In both Sr₂Fe_0.5Ru_0.5O₄ and SrFe_0.5Ru_0.5O₃, the original ruthenium (Ru) and the dopant iron (Fe) atoms adopt 3-dimensional and 2-dimensional G-type structures, respectively. The hybridization between Fe-3d and Ru-4d is comparatively weaker than in other double perovskite systems. The interplay between strong correlations and reduced itinerancy results in significant spin splitting at Fe and Ru sites. Consequently, a charge transfer process, along with the super-exchange effect, leads to antiferromagnetically coupled Fe³⁺ and Ru⁵⁺ ions and establishes a semiconducting ferrimagnetic order. Subsequent DMFT calculations demonstrate the persistence of the ferrimagnetic order even at room temperature (300 K). These findings align with prior reports on SrFe_0.5Ru_0.5O₃, thus reinforcing the notion that 3d-4d transition metal oxides hold considerable promise as candidates for high-performance spintronic devices, such as spin-valve sensors and spintronic giant magnetoresistance devices.

Off-diagonal approach to the exact solution of quantum integrable systems

Yi Qiao(乔艺), Junpeng Cao(曹俊鹏), Wen-Li Yang(杨文力), Kangjie Shi(石康杰), and Yupeng Wang(王玉鹏)

Chin. Phys. B, 2023, 32 (11): 117504. DOI: 10.1088/1674-1056/ad0774

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We investigate the t-W scheme for the anti-ferromagnetic XXX spin chain under both periodic and open boundary conditions. We propose a new parametrization of the eigenvalues of the transfer matrix. Based on it, we obtain the exact solution of the system. By analyzing the distribution of zero roots at the ground state, we obtain the explicit expressions of the eigenfunctions of the transfer matrix and the associated $\mathbb{W}$ operator (see Eqs. (10) and (70)) in the thermodynamic limit. We find that the ratio of the quantum determinant with the eigenvalue of $\mathbb{W}$ operator for the ground state exhibits exponential decay behavior. Thus this fact ensures that the so-called inversion relation (the t-W relation without the W-term) can be used to study the ground state properties of quantum integrable systems with/without U(1)-symmetry in the thermodynamic limit.

Temperature-dependent photoluminescence of lead-free cesium tin halide perovskite microplates

Jiayu Tan(谭佳雨), Yixuan Zhou(周译玄), De Lu(卢德), Xukun Feng(冯旭坤), Yuqi Liu(刘玉琪), Mengen Zhang(张蒙恩), Fangzhengyi Lu(卢方正一), Yuanyuan Huang(黄媛媛), and Xinlong Xu(徐新龙)

Chin. Phys. B, 2023, 32 (11): 117802. DOI: 10.1088/1674-1056/ad028e

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Tin halide perovskites recently have attracted extensive research attention due to their similar electronic and band structures but non-toxicity compared with their lead analogues. In this work, we prepare high-quality CsSnX₃ (X=Br, I) microplates with lateral sizes of around 1-4 μ m by chemical vapor deposition and investigate their low-temperature photoluminescence (PL) properties. A remarkable splitting of PL peaks of the CsSnBr₃ microplate is observed at low temperatures. Besides the possible structural phase transition at below 70 K, the multi-peak fittings using Gauss functions and the power-dependent saturation phenomenon suggest that the PL could also be influenced by the conversion from the emission of bound excitons into free excitons. With the increase of temperature, the peak position shows a blueshift tendency for CsSnI₃, which is governed by thermal expansion. However, the peak position of the CsSnBr₃ microplate exhibits a transition from redshift to blueshift at ～ 160 K. The full width at half maximum of CsSnX₃ broadens with increasing temperature, and the fitting results imply that longitudinal optical phonons dominate the electron-phonon coupling and the coupling strength is much more robust in CsSnBr₃ than in CsSnI₃. The PL intensity of CsSnX₃ microplates is suppressed due to the enhanced non-radiative relaxation and exciton dissociation competing with radiative recombination. According to the Arrhenius law, the exciton binding energy of CsSnBr₃ is ～ 38.4 meV, slightly smaller than that of CsSnI₃.

Fabrication and research of bi-functional CuNi₂S₄ nanosheets decorated TiO₂/CuNi₂S₄ heterojunction photoanode for photoelectrochemical water splitting

Wei Jin(金伟), Liyuan Zhang(张立媛), Wenjing Zhang(张文静), Qian Sun(孙倩), Dekai Zhang(张德恺), Hui Miao(苗慧), and Xiaoyun Hu(胡晓云)

Chin. Phys. B, 2023, 32 (11): 118201. DOI: 10.1088/1674-1056/acef06

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As a traditional n-type semiconductor, TiO₂ has good UV absorption ability and stable physical and chemical properties. However, its wide band gap and low oxygen evolution reaction (OER) activity limit its application in the field of photoelectrochemical (PEC) water splitting. In this work, a type-II TiO₂/CuNi₂S₄ heterojunction photoanode is successfully constructed, which expanded the light absorption range to visible and enhanced the OER activity. Firstly, TiO₂ nanotubes (NTs) thin films are prepared on Ti substrates by two-step anodization, and then the bi-functional electrocatalytic material CuNi₂S₄ is grown on TiO₂ NTs in the shape of nanosheets (NSs) in situ by solvothermal method. As a bi-functional electrocatalytic material, CuNi₂S₄ has good visible light absorption property as well as OER catalytic activity. Compared with TiO₂, the IPCE value of TiO₂/CuNi₂S₄ is 2.59% at 635 nm, and that of TiO₂ is a mere 0.002%. The separation efficiency and injection efficiency increase from 2.49% and 31.52% to 3.61% and 87.77%, respectively. At 1.23 V vs. RHE, the maximum photocurrent density is 0.26 mA/cm², which is 2.6 times than that of TiO₂ (0.11 mA/cm²), and can be maintained at 0.25 mA/cm² for at least 2 h under light illumination. Moreover, a hydrogen production rate of 4.21 μ mol· cm^-2·h^-1 is achieved within 2 h. This work provides a new idea for the application of TiO₂ in the field of PEC water splitting and the construction of efficient and stable photoelectronic devices.

A fast-response self-powered UV-Vis-NIR broadband photodetector based on a AgIn₅Se₈/t-Se heterojunction

Kang Li(李康), Lei Xu(许磊), Qidong Lu(陆启东), and Peng Hu(胡鹏)

Chin. Phys. B, 2023, 32 (11): 118503. DOI: 10.1088/1674-1056/acec44

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A type II p-n heterojunction could improve the photodetection performance of a photodetector due to the excellent ability of carrier separation. N-type AgIn₅Se₈ (AIS) exhibits a large optical absorption coefficient, high optical conductivity and a suitable bandgap, and shows potential application in broadband photodetection. Even though our previous study on AgIn₅Se₈/FePSe₃ obtained a good response speed, it still gave low responsivity due to the poor quality of the p-type FePSe₃ thin film. Se, with a direct bandgap (around 1.7 eV), p-type conductivity, high electron mobility and high carrier density, is likely to form a low-dimensional structure, which leads to an increase in the effective contact area of the heterojunction and further improves the photodetector performance. In this work, continuous and dense t-Se thin film was prepared by electrochemical deposition. The self-powered AgIn₅Se₈/t-Se heterojunction photodetector exhibited a broadband detection range from 365 nm to 1200 nm. The responsivity and detectivity of the heterojunction photodetector were 32 μ A/W and 1.8× 10⁹ Jones, respectively, which are around 9 and 4 times higher than those of the AgIn₅Se₈/FePSe₃ heterojunction photodetector. The main reason for this is the good quality of the t-Se thin film and the formation of the low-dimensional t-Se nanoribbons, which optimized the transport pathway of carriers. The results indicate that the AgIn₅Se₈/t-Se heterojunction is an excellent candidate for broadband and self-powered photoelectronic devices.

Reconstructing in vivo spatially offset Raman spectroscopy of human skin tissue using a GPU-accelerated Monte Carlo platform

Yun-He Zhang(张云鹤), Huan-Zheng Zhu(朱桓正), Yong-Jiang Dong(董泳江), Jia Zeng(曾佳), Xin-Peng Han(韩新鹏), Ivan A. Bratchenko, Fu-Rong Zhang(张富荣), Si-Yuan Xu(许思源), and Shuang Wang(王爽)

Chin. Phys. B, 2023, 32 (11): 118702. DOI: 10.1088/1674-1056/acef05

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As one type of spatially offset Raman spectroscopy (SORS), inverse SORS is particularly suited to in vivo biomedical measurements due to its ring-shaped illumination scheme. To explain inhomogeneous Raman scattering during in vivo inverse SORS measurements, the light-tissue interactions when excitation and regenerated Raman photons propagate in skin tissue were studied using Monte Carlo simulation. An eight-layered skin model was first built based on the latest transmission parameters. Then, an open-source platform, Monte Carlo eXtreme (MCX), was adapted to study the distribution of 785 nm excitation photons inside the model with an inverse spatially shifted annular beam. The excitation photons were converted to emission photons by an inverse distribution method based on excitation flux with spatial offsets Δs of 1 mm, 2 mm, 3 mm and 5 mm. The intrinsic Raman spectra from separated skin layers were measured by continuous linear scanning to improve the simulation accuracy. The obtained results explain why the spectral detection depth gradually increases with increasing spatial offset, and address how the intrinsic Raman spectrum from deep skin layers is distorted by the reabsorption and scattering of the superficial tissue constituents. Meanwhile, it is demonstrated that the spectral contribution from subcutaneous fat will be improved when the offset increases to 5 mm, and the highest detection efficiency for dermal layer spectral detection could be achieved when Δs = 2 mm. Reasonably good matching between the calculated spectrum and the measured in vivo inverse SORS was achieved, thus demonstrating great utility of our modeling method and an approach to help understand the clinical measurements.

Assessing pathological features of breast cancer via the multimodal information of multiphoton and Raman imaging

Bing-Ran Gao(高冰然), Xi-Wen Chen(陈希文), Bao-Ping Zhang(张宝萍), Ivan A. Bratchenko, Jian-Xin Chen(陈建新), Shuang Wang(王爽), and Si-Yuan Xu(许思源)

Chin. Phys. B, 2023, 32 (11): 118703. DOI: 10.1088/1674-1056/acea67

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For unveiling the pathological evolution of breast cancer, nonlinear multiphoton microscopic (MPM) and confocal Raman microspectral imaging (CRMI) techniques were both utilized to address the structural and constitutional characteristics of healthy (H), ductal carcinoma in situ (DCIS), and invasive ductal carcinoma (IDC) tissues. MPM-based techniques, including two-photon excited fluorescence (TPEF) and second harmonic generation (SHG), visualized label-free and the fine structure of breast tissue. Meanwhile, CRMI not only presented the chemical images of investigated samples with the K-mean cluster analysis method (KCA), but also pictured the distribution of components in the scanned area through univariate imaging. MPM images illustrated that the cancer cells first arranged around the basement membrane of the duct, then proliferated to fill the lumens of the duct, and finally broke through the basement membrane to infiltrate into the stroma. Although the Raman imaging failed to visualize the cell structure with high resolution, it explained spectroscopically the gradual increase of nucleic acid and protein components inside the ducts as cancer cells proliferated, and displayed the distribution pattern of each biological component during the evolution of breast cancer. Thus, the combination of MPM and CRMI provided new insights into the on-site pathological diagnosis of malignant breast cancer, also ensured technical support for the development of multimodal optical imaging techniques for precise histopathological analysis.

Effect of mono-/divalent metal ions on the conductivity characteristics of DNA solutions transferring through a microfluidic channel

Jie Zhu(朱洁), Jing Xue(薛菁), Wei Zhao(赵伟), Chen Zhang(张琛), Xiaoqiang Feng(冯晓强), and Kaige Wang(王凯歌)

Chin. Phys. B, 2023, 32 (11): 118704. DOI: 10.1088/1674-1056/acfaf6

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Interactions between deoxyribonucleic acid (DNA) and metal ions are vital for maintaining life functions, however, there are still unsolved questions about its mechanisms. It is of great practical significance to study these issues for medical chip design, drug development, health care, etc. In this investigation, the conductivity properties of λ -DNA solutions with mono-/divalent metal ions (Na⁺, K⁺, Mg²⁺, and Ca²⁺) are experimentally studied as they are electrically driven through a 5 μ m microfluidic channel. Experimental data indicate that the conductivities of λ -DNA solutions with metal ions (M⁺/M²⁺) basically tend to reduce firstly and then increase as the voltage increases, of which the turning points varied with the metal ions. When the voltage surpasses turning points, the conductivity of λ -DNA-M⁺ solutions increases with the concentration of metal ions, while that of λ -DNA-M²⁺ solutions decrease. Moreover, the conductivity of λ -DNA-M²⁺ solutions is always smaller than that of λ -DNA-M⁺ solutions, and with high-concentration M²⁺, it is even smaller than that of the λ -DNA solution. The main reasons for the above findings could be attributed to the polarization of electrodes and different mechanisms of interactions between metal ions and λ -DNA molecules. This investigation is helpful for the precise manipulation of single DNA molecules in micro-/nanofluidic space and the design of new biomedical micro-/nanofluidic sensors.

Directional-to-random transition of cell cluster migration

Yang Zeng(曾阳), Bingchen Che(车丙晨), Dan Sun(孙聃), Ce Zhang(张策), and Guangyin Jing(经光银)

Chin. Phys. B, 2023, 32 (11): 118705. DOI: 10.1088/1674-1056/acf704

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Efficient cell migration is crucial for the functioning of biological processes, e.g., morphogenesis, wound healing, and cancer metastasis. In this study, we monitor the migratory behavior of the 3D fibroblast clusters using live cell microscopy, and find that crowded environment affects cell migration, i.e., crowding leads to directional migration at the cluster's periphery. The number of cell layers being stacked during seeding determines the directional-to-random transition. Intriguingly, the migratory behavior of cell clusters resembles the dispersion dynamics of clouds of passive particles, indicating that the biological process is driven by physical effects (e.g., entropy) rather than cell communication. Our findings highlight the role of intrinsic physical characteristics, such as crowding, in regulating biological behavior, and suggest new therapeutic approaches targeting at cancer metastasis.

MatChat: A large language model and application service platform for materials science

Zi-Yi Chen(陈子逸), Fan-Kai Xie(谢帆恺), Meng Wan(万萌), Yang Yuan(袁扬), Miao Liu(刘淼), Zong-Guo Wang(王宗国), Sheng Meng(孟胜), and Yan-Gang Wang(王彦棡)

Chin. Phys. B, 2023, 32 (11): 118104. DOI: 10.1088/1674-1056/ad04cb

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The prediction of chemical synthesis pathways plays a pivotal role in materials science research. Challenges, such as the complexity of synthesis pathways and the lack of comprehensive datasets, currently hinder our ability to predict these chemical processes accurately. However, recent advancements in generative artificial intelligence (GAI), including automated text generation and question-answering systems, coupled with fine-tuning techniques, have facilitated the deployment of large-scale AI models tailored to specific domains. In this study, we harness the power of the LLaMA2-7B model and enhance it through a learning process that incorporates 13878 pieces of structured material knowledge data. This specialized AI model, named MatChat, focuses on predicting inorganic material synthesis pathways. MatChat exhibits remarkable proficiency in generating and reasoning with knowledge in materials science. Although MatChat requires further refinement to meet the diverse material design needs, this research undeniably highlights its impressive reasoning capabilities and innovative potential in materials science. MatChat is now accessible online and open for use, with both the model and its application framework available as open source. This study establishes a robust foundation for collaborative innovation in the integration of generative AI in materials science.

Benchmarking calculations of excitation energies and transition properties with spectroscopic accuracy of highly charged ions used for the fusion plasma and astrophysical plasma

Chunyu Zhang(张春雨), Kai Wang(王凯), Ran Si(司然), Jinqing Li(李金晴), Changxian Song(宋昌仙), Sijie Wu(吴思捷), Bishuang Yan(严碧霜), and Chongyang Chen(陈重阳)

Chin. Phys. B, 2023, 32 (11): 113102. DOI: 10.1088/1674-1056/acef07

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Atomic radiative data such as excitation energies, transition wavelengths, radiative rates, and level lifetimes with high precision are the essential parameters for the abundance analysis, simulation, and diagnostics in fusion and astrophysical plasmas. In this work, we mainly focus on reviewing our two projects performed in the past decade. One is about the ions with $Z\lesssim 30$ that are generally of astrophysical interest, and the other one is about the highly charged krypton (Z=36) and tungsten (Z=74) ions that are relevant in research of magnetic confinement fusion. Two different and independent methods, namely, multiconfiguration Dirac-Hartree-Fock (MCDHF) and the relativistic many-body perturbation theory (RMBPT) are usually used in our studies. As a complement/extension to our previous works for highly charged tungsten ions with open M-shell and open N-shell, we also mainly focus on presenting and discussing our complete RMBPT and MCDHF calculations for the excitation energies, wavelengths, electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transition properties, and level lifetimes for the lowest 148 levels belonging to the 3l³ configurations in Al-like W⁶¹⁺. We also summarize the uncertainties of our systematical theoretical calculations, by cross-checking/validating our datasets from our RMBPT and MCDHF calculations, and by detailed comparisons with available accurate observations and other theoretical calculations. The data are openly available in Science Data Bank at https://doi.org/10.57760/sciencedb.10569.

An effective method to calculate the electron impact excitation cross sections of helium from ground state to a final channel in the whole energy region

Rui Sun(孙瑞), De-Ling Zeng(曾德灵), Rui Jin(金锐), Xiao-Ying Han(韩小英), Xiang Gao(高翔), and Jia-Ming Li(李家明)

Chin. Phys. B, 2023, 32 (11): 113401. DOI: 10.1088/1674-1056/acf11f

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The electron impact excitation (EIE) cross sections of an atom/ion in the whole energy region are needed in many research fields, such as astrophysics studies, inertial confinement fusion researches and so on. In the present work, an effective method to calculate the EIE cross sections of an atom/ion in the whole energy region is presented. We use the EIE cross sections of helium as an illustration example. The optical forbidden 1¹S-n¹S (n = 2-4) and optical allowed 1¹S-n¹P (n=2-4) excitation cross sections are calculated in the whole energy region using the scheme that combines the partial wave R-matrix method and the first Born approximation. The calculated cross sections are in good agreement with the available experimental measurements. Based on these accurate cross sections of our calculation, we find that the ratios between the accurate cross sections and Born cross sections are nearly the same for different excitation final states in the same channel. According to this interesting property, a universal correction function is proposed and given to calculate the accurate EIE cross sections with the same computational efforts of the widely used Born cross sections, which should be very useful in the related application fields. The datasets presented in this paper are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00142.

Oscillator strength and cross section study of the valence-shell excitations of NO₂ by fast electron scattering

Qiang Sun(孙强), Jin-Feng Chen(陈锦峰), Zhi-Wei Nie(聂智伟), Jian-Hui Zhu(朱剑辉), and Lin-Fan Zhu(朱林繁)

Chin. Phys. B, 2023, 32 (11): 113402. DOI: 10.1088/1674-1056/acf5d6

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Oscillator strengths and cross sections of the valence-shell excitations in NO₂ are of great significance in testing the theoretical calculations and monitoring the state of the ozone layer in the earth's atmosphere. In the present work, the generalized oscillator strengths of the valence-shell excitations in NO₂ were obtained based on the fast electron scattering technique at an incident electron energy of 1.5 keV and an energy resolution of about 70 meV. By extrapolating the generalized oscillator strengths to the limit of a zero squared momentum transfer, the optical oscillator strengths for the dipole-allowed transitions have been obtained, which provide an independent cross check to the previous experimental results. Based on the BE-scaling method, the corresponding integral cross sections have also been derived systematically from the excitation threshold to 5000 eV. The present dynamic parameters can provide the fundamental spectroscopic data of NO₂ and have important applications in the studies of atmospheric science. The datasets presented in this paper, including the GOSs, OOSs and ICSs, are openly available at https://doi.org/10.57760/sciencedb.j00113.00156.

Performance optimization of scintillator neutron detectors for EMD in CSNS

Xiaojie Cai(蔡小杰), Qian Yu(于潜), Chang Huang(黄畅), Bin Tang(唐彬), Shihui Zhou(周诗慧), Xiaohu Wang(王小胡), Xiuping Yue(岳秀萍), and Zhijia Sun(孙志嘉)

Chin. Phys. B, 2023, 32 (11): 110701. DOI: 10.1088/1674-1056/acd8a2

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Chinese Spallation Neutron Source (CSNS) has successfully produced its first neutron beam in 28th August 2017. It has been running steadily from March, 2018. According to the construction plan, the engineering materials diffractometer (EMD) will be installed between 2019-2023. This instrument requires the neutron detectors with the cover area near 3 m² in two 90° neutron diffraction angle positions, the neutron detecting efficiency is better than 40%@1 Å, and the spatial resolution is better than 4 mm×200 mm in horizontal and vertical directions respectively. We have developed a one-dimensional position-sensitive neutron detector based on the oblique ⁶LiF/ZnS(Ag) scintillators, wavelength shifting fibers, and SiPMs (silicon photomultipliers) readout. The inhomogeneity of the neutron detection efficiency between each pixel and each detector module, which caused by the inconsistency of the wave-length shifting fibers in collecting scintillation photons, needs to be mitigated before the installation. A performance optimization experiment of the detector modules was carried out on the BL20 (beam line 20) of CSNS. Using water sample, the neutron beam with Φ 5 mm exit hole was dispersed related evenly into the forward space. According to the neutron counts of each pixel of the detector module, the readout electronics threshold of each pixel is adjusted. Compared with the unadjusted detector module, the inhomogeneity of the detection efficiency for the adjusted one has been improved from 69% to 90%. The test result of the diffraction peak of the standard sample Si showed that the adjusted detector module works well.

Ultrafast two-dimensional x-ray imager with temporal fiducial pulses for laser-produced plasmas

Zheng-Dong Liu(刘正东), Jia-Yong Zhong(仲佳勇), Xiao-Hui Yuan(远晓辉), Ya-Peng Zhang(张雅芃), Jia-Wen Yao(姚嘉文), Zuo-Lin Ma(马作霖), Xiang-Yan Xu(徐向晏), Yan-Hua Xue(薛彦华), Zhe Zhang(张喆), Da-Wei Yuan(袁大伟), Min-Rui Zhang(张敏睿), Bing-Jun Li(李炳均), Hao-Chen Gu(谷昊琛), Yu Dai(戴羽), Cheng-Long Zhang(张成龙), Yu-Feng Dong(董玉峰), Peng Zhou(周鹏), Xin-Jie Ma(马鑫杰), Yun-Feng Ma(马云峰), Xue-Jie Bai(白雪洁), Gao-Yang Liu(刘高扬), Jin-Shou Tian(田进寿), Gang Zhao(赵刚), and Jie Zhang(张杰)

Chin. Phys. B, 2023, 32 (11): 110702. DOI: 10.1088/1674-1056/ace766

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It is challenging to make an ultrafast diagnosis of the temporal evolution of small and short-lived plasma in two dimensions. To overcome this difficulty, we have developed a well-timed diagnostic utilizing an x-ray streak camera equipped with a row of multi-pinhole arrays. By processing multiple sets of one-dimensional streaked image data acquired from various pinholes, we are capable of reconstructing high-resolution two-dimensional images with a temporal resolution of 38 ps and a spatial resolution of 18 μm. The temporal fiducial pulses accessed from external sources can advance the precise timing and accurately determine the arrival time of the laser. Moreover, it can correct the nonlinear sweeping speed of the streak camera. The effectiveness of this diagnostic has been successfully verified at the Shenguang-II laser facility, providing an indispensable tool for observing complex physical phenomena, such as the implosion process of laser-fusion experiments.

Design and calibration of an elliptical crystal spectrometer for the diagnosis of proton-induced x-ray emission (PIXE)

Yanlyu Fang(方言律), Dongyu Li(李东彧), Hao Cheng(程浩), Yuan Gao(高原), Ze-Qing Shen(申泽清), Tong Yang(杨童), Yu-Ze Li(李昱泽), Ya-Dong Xia(夏亚东), Yang Yan(晏炀), Sha Yan(颜莎), Chen Lin(林晨), and Xue-Qing Yan(颜学庆)

Chin. Phys. B, 2023, 32 (11): 110703. DOI: 10.1088/1674-1056/acf493

Abstract ( 150 )

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Laser-driven proton-induced x-ray emission (laser-PIXE) is a nuclear analysis method based on the compact laser ion accelerator. Due to the transient process of ion acceleration, the laser-PIXE signals are usually spurted within nanoseconds and accompanied by strong electromagnetic pulses (EMP), so traditional multi-channel detectors are no longer applicable. In this work, we designed a reflective elliptical crystal spectrometer for the diagnosis of laser-PIXE. The device can detect the energy range of 1 keV-11 keV with a high resolution. A calibration experiment was completed on the electrostatic accelerator of Peking University using samples of Al, Ti, Cu, and ceramic artifacts. The detection efficiency of the elliptical crystal spectrometer was obtained in the order of 10^-9.

A combined magnetic field stabilization system for improving the stability of ⁴⁰Ca⁺ optical clock

Mengyan Zeng(曾孟彦), Zixiao Ma(马子晓), Ruming Hu(胡如明), Baolin Zhang(张宝林), Yanmei Hao(郝艳梅), Huaqing Zhang(张华青), Yao Huang(黄垚), Hua Guan(管桦), and Kelin Gao(高克林)

Chin. Phys. B, 2023, 32 (11): 110704. DOI: 10.1088/1674-1056/acf5d5

Abstract ( 238 )

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Future applications of portable ⁴⁰Ca⁺ optical clocks require reliable magnetic field stabilization to improve frequency stability, which can be achieved by implementing an active and passive magnetic field noise suppression system. On the one hand, we have optimized the magnetic shielding performance of the portable optical clock by reducing its apertures and optimizing its geometry; on the other hand, we have introduced an active magnetic field noise suppression system to further suppress the magnetic field noise experienced by the ions. These efforts reduced the ambient magnetic field noise by about 10000 times, significantly reduced the linewidth of the clock transition spectrum, improved the stability of the portable ⁴⁰Ca⁺ optical clock, and created the conditions for using portable optical clocks in non-laboratory magnetic field environments. This active magnetic field suppression scheme has the advantages of simple installation and wide applicability.

A cryogenic radio-frequency ion trap for a ⁴⁰Ca⁺ optical clock

Mengyan Zeng(曾孟彦), Yao Huang(黄垚), Baolin Zhang(张宝林), Zixiao Ma(马子晓), Yanmei Hao(郝艳梅), Ruming Hu(胡如明), Huaqing Zhang(张华青), Hua Guan(管桦), and Kelin Gao(高克林)

Chin. Phys. B, 2023, 32 (11): 113701. DOI: 10.1088/1674-1056/acc807

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A liquid-nitrogen cryogenic ⁴⁰Ca⁺ optical clock is presented that is designed to greatly reduce the blackbody radiation (BBR) shift. The ion trap, the electrodes and the in-vacuum BBR shield are installed under the liquid-nitrogen container, keeping the ions in a cryogenic environment at liquid-nitrogen temperature. Compared with the first design in our previous work, many improvements have been made to increase the performance. The liquid-nitrogen maintenance time has been increased by about three times by increasing the volume of the liquid-nitrogen container; the trap position recovery time after refilling the liquid-nitrogen container has been decreased more than three times by using a better fixation scheme in the liquid-nitrogen container; and the magnetic field noise felt by the ions has been decreased more than three times by a better design of the magnetic shielding system. These optimizations make the scheme for reducing the BBR shift uncertainty of liquid-nitrogen-cooled optical clocks more mature and stable, and develop a stable lock with a narrower linewidth spectrum, which would be very beneficial for further reducing the overall systematic uncertainty of optical clocks.

Performance of the merged APPLE-Knot undulator for soft x-ray beamline in medium energy ring

Rui Cheng(成锐), Fa-Yuan Zhang(张发远), He-Ming Zha(查鹤鸣), and Shan Qiao(乔山)

Chin. Phys. B, 2023, 32 (11): 114102. DOI: 10.1088/1674-1056/acd924

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APPLE-Knot undulator can effectively solve the on-axis heat load problem and is proven to perform well in VUV beamline and soft x-ray beamline in high energy storage ring. However, for soft x-ray beamline in a medium energy ring, whether the APPLE-Knot undulator excels the APPLE undulator is still a question. Here, a merged APPLE-Knot undulator is studied to generate soft x-ray in a medium energy ring. Its advantages and problems are discussed. Though the on-axis heat load of the APPLE-Knot undulator is lower in linear polarization modes compared to the APPLE undulator, its flux is lower. The APPLE-Knot undulator shows no advantage when only fundamental harmonic is needed. However, in circular polarization mode, the APPLE-Knot undulator shows the ability to cover a broader energy range which can remedy the notable shortcoming of the APPLE undulator.

Fast and perfect state transfer in superconducting circuit with tunable coupler ^Hot!

Chi Zhang(张驰), Tian-Le Wang(王天乐), Ze-An Zhao(赵泽安), Xiao-Yan Yang(杨小燕), Liang-Liang Guo(郭亮亮), Zhi-Long Jia(贾志龙), Peng Duan(段鹏), and Guo-Ping Guo(郭国平)

Chin. Phys. B, 2023, 32 (11): 110305. DOI: 10.1088/1674-1056/acf496

Abstract ( 298 )

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In quantum computation and quantum information processing, the manipulation and engineering of quantum systems to suit certain purposes are an ongoing task. One such example is quantum state transfer (QST), an essential requirement for both quantum communication and large-scale quantum computation. Here we engineer a chain of four superconducting qubits with tunable couplers to realize the perfect state transfer (PST) protocol originally proposed in quantum spin networks and successfully demonstrate the efficient transfer of an arbitrary single-qubit state from one end of the chain to the other, achieving a high fidelity of 0.986 in just 25 ns. This demonstrated QST is readily to extend to larger chain and multi-node configurations, thus serving as a desirable tool for scalable quantum information processing.

Direct measurement of nonlocal quantum states without approximation ^Hot!

Gang Yang(杨冈), Ran Yang(杨然), Yan-Xiao Gong(龚彦晓), and Shi-Ning Zhu(祝世宁)

Chin. Phys. B, 2023, 32 (11): 110306. DOI: 10.1088/1674-1056/acf5d7

Abstract ( 349 )

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Efficient acquiring information from a quantum state is important for research in fundamental quantum physics and quantum information applications. Instead of using standard quantum state tomography method with reconstruction algorithm, weak values were proposed to directly measure density matrix elements of quantum state. Recently, similar to the concept of weak value, modular values were introduced to extend the direct measurement scheme to nonlocal quantum wavefunction. However, this method still involves approximations, which leads to inherent low precision. Here, we propose a new scheme which enables direct measurement for ideal value of the nonlocal density matrix element without taking approximations. Our scheme allows more accurate characterization of nonlocal quantum states, and therefore has greater advantages in practical measurement scenarios.

Low-damage photolithography for magnetically doped (Bi,Sb)₂Te₃ quantum anomalous Hall thin films ^Hot!

Zhiting Gao(高志廷), Minghua Guo(郭明华), Zichen Lian(连梓臣), Yaoxin Li(李耀鑫), Yunhe Bai(白云鹤), Xiao Feng(冯硝), Ke He(何珂), Yayu Wang(王亚愚), Chang Liu(刘畅), and Jinsong Zhang(张金松)

Chin. Phys. B, 2023, 32 (11): 117303. DOI: 10.1088/1674-1056/ad0147

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We have developed a low-damage photolithography method for magnetically doped (Bi,Sb)₂Te₃ quantum anomalous Hall (QAH) thin films incorporating an additional resist layer of poly(methyl methacrylate) (PMMA). By performing control experiments on the transport properties of five devices at varied gate voltages (V_gs), we revealed that the modified photolithography method enables fabricating QAH devices with the transport and magnetic properties unaffected by fabrication process. Our experiment represents a step towards the production of novel micro-structured electronic devices based on the dissipationless QAH chiral edge states.

Intrinsic electronic structure and nodeless superconducting gap of YBa₂Cu₃O_7-δ observed by spatially-resolved laser-based angle resolved photoemission spectroscopy ^Hot!

Shuaishuai Li(李帅帅), Taimin Miao(苗泰民), Chaohui Yin(殷超辉), Yinghao Li(李颖昊), Hongtao Yan(闫宏涛), Yiwen Chen(陈逸雯), Bo Liang(梁波), Hao Chen(陈浩), Wenpei Zhu(朱文培), Shenjin Zhang(张申金), Zhimin Wang(王志敏), Fengfeng Zhang(张丰丰), Feng Yang(杨峰), Qinjun Peng(彭钦军), Chengtian Lin(林成天), Hanqing Mao(毛寒青), Guodong Liu(刘国东), Zuyan Xu(许祖彦), Lin Zhao(赵林), and X J Zhou(周兴江)

Chin. Phys. B, 2023, 32 (11): 117401. DOI: 10.1088/1674-1056/acf498

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The spatially-resolved laser-based high-resolution angle resolved photoemission spectroscopy (ARPES) measurements have been performed on the optimally-doped YBa₂Cu₃O_7-δ (Y123) superconductor. For the first time, we found the region from the cleaved surface that reveals clear bulk electronic properties. The intrinsic Fermi surface and band structures of Y123 were observed. The Fermi surface-dependent and momentum-dependent superconducting gap was determined which is nodeless and consistent with the d+is gap form.

Analytical wave solutions of an electronically and biologically important model via two efficient schemes

Qingbo Huang, Asim Zafar, M. Raheel, and Ahmet Bekir

Chin. Phys. B, 2023, 32 (11): 110201. DOI: 10.1088/1674-1056/ace61f

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We search for analytical wave solutions of an electronically and biologically important model named as the Fitzhugh-Nagumo model with truncated M-fractional derivative, in which the exp_a function and extended sinh-Gordon equation expansion (EShGEE) schemes are utilized. The solutions obtained include dark, bright, dark-bright, periodic and other kinds of solitons. These analytical wave solutions are gained and verified with the use of Mathematica software. These solutions do not exist in literature. Some of the solutions are demonstrated by 2D, 3D and contour graphs. This model is mostly used in circuit theory, transmission of nerve impulses, and population genetics. Finally, both the schemes are more applicable, reliable and significant to deal with the fractional nonlinear partial differential equations.

Finite-time H_∞ filtering for Markov jump systems with uniform quantization

Jingjing Dong(董敬敬), Xiaofeng Ma(马晓峰), Xiaoqing Zhang(张晓庆), Jianping Zhou(周建平), and Zhen Wang(王震)

Chin. Phys. B, 2023, 32 (11): 110202. DOI: 10.1088/1674-1056/acedf5

Abstract ( 134 )

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This paper is concerned with finite-time H_∞ filtering for Markov jump systems with uniform quantization. The objective is to design quantized mode-dependent filters to ensure that the filtering error system is not only mean-square finite-time bounded but also has a prescribed finite-time H_∞ performance. First, the case where the switching modes of the filter align with those of the MJS is considered. A numerically tractable filter design approach is proposed utilizing a mode-dependent Lyapunov function, Schur's complement, and Dynkin's formula. Then, the study is extended to a scenario where the switching modes of the filter can differ from those of the MJS. To address this situation, a mode-mismatched filter design approach is developed by leveraging a hidden Markov model to describe the asynchronous mode switching and the double expectation formula. Finally, a spring system model subject to a Markov chain is employed to validate the effectiveness of the quantized filter design approaches.

Rectified transport of a single vibration-driven vehicle in the asymmetric channel

Yu-Wen Hao(郝钰文), Bao-Quan Ai(艾保全), Fei Tan(谭飞), Xiao-Yuan Yu(余孝源), and Feng-Guo Li(李丰果)

Chin. Phys. B, 2023, 32 (11): 110203. DOI: 10.1088/1674-1056/acc6b7

Abstract ( 138 )

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The rectification transport of a single vibration-driven self-propelled vehicle in a two-dimensional left-right asymmetric channel was experimentally investigated. The rectification efficiency of the vehicle moving from the center to the exit was statistically obtained for the range of channel widths, inter-channel asymmetry degrees, and platform tilt angles. The trajectory of its movement was also analyzed. It was found that the structure of the channel provides the main influence. Different channel shapes lead to different ranges of unfavorable widths, and transport efficiency decreases when the asymmetry diminishes — the two channels converge. The addition of external gravity does not counteract the structural limitations, but only affects the probability of departure.

Optical anapole modes in hybrid metal-dielectric nanoantenna for near-field enhancement and optical sensing Suggested by editors

Debao Wang(王德宝), Jingwei Lv(吕靖薇), Wei Liu(刘伟), Yanru Ren(任艳茹), Wei Li(李薇), Xinchen Xu(许鑫辰), Chao Liu(刘超), and Paul K Chu(朱剑豪)

Chin. Phys. B, 2023, 32 (11): 110204. DOI: 10.1088/1674-1056/acfaf4

Abstract ( 223 )

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Metal-dielectric nanostructures in the optical anapole modes are essential for light-matter interactions due to the low material loss and high near-field enhancement. Herein, a hybrid metal-dielectric nanoantenna composed of six wedge-shaped gold (Au) nanoblocks as well as silica (SiO₂) and silicon (Si) nanodiscs is designed and analyzed by the finite element method (FEM). The nanoantenna exhibits flexibility in excitation and manipulation of the anapole mode through the strong coupling between the metal and dielectrics, consequently improving the near-field enhancement at the gap. By systematically optimizing the structural parameters, the electric field enhancement factors at wavelengths corresponding to the anapole modes (AM1 and AM2) can be increased to 518 and 1482, respectively. Moreover, the nanoantenna delivers great performance in optical sensing such as a sensitivity of 550 nm/RIU. The results provide guidance and insights into enhancing the coupling between metals and dielectrics for applications such as surface-enhanced Raman scattering and optical sensing.

Theoretical study of (e, 2e) triple differential cross section of 1b_3g orbital of ethylene by vibrational multi-center distorted-wave method Suggested by editors

Zhenpeng Wang(王振鹏), Maomao Gong(宫毛毛), Xingyu Li(李星宇), Songbin Zhang(张松斌), and Xiangjun Chen(陈向军)

Chin. Phys. B, 2023, 32 (11): 110205. DOI: 10.1088/1674-1056/acec45

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The vibrational motions are usually neglected when calculating (e,2e) triple differential cross sections (TDCSs) of molecules. Here, multi-center distorted-wave method (MCDW) has been modified by including molecular vibrations. This vibrational MCDW method is employed to calculate the TDCSs of 1b_3g orbital of ethylene at low (100 eV) and medium (250 eV) incident electron energies in coplanar asymmetric kinematic condition. The results show that molecular vibrations significantly influence the angular distributions of the TDCSs, especially in the binary region along momentum transfer near the Bethe ridge.

Residual symmetry, CRE integrability and interaction solutions of two higher-dimensional shallow water wave equations

Xi-Zhong Liu(刘希忠), Jie-Tong Li(李界通), and Jun Yu(俞军)

Chin. Phys. B, 2023, 32 (11): 110206. DOI: 10.1088/1674-1056/acf11c

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Two (3+1)-dimensional shallow water wave equations are studied by using residual symmetry and the consistent Riccati expansion (CRE) method. Through localization of residual symmetries, symmetry reduction solutions of the two equations are obtained. The CRE method is applied to the two equations to obtain new Bäcklund transformations from which a type of interesting interaction solution between solitons and periodic waves is generated.

Optimal driving field for multipartite quantum battery coupled with a common thermal bath Suggested by editors

Z Q Yang(杨梓骞), L K Zhou(周立坤), Z Y Zhou(周正阳), G R Jin(金光日), L Cheng(程龙), and X G Wang(王晓光)

Chin. Phys. B, 2023, 32 (11): 110301. DOI: 10.1088/1674-1056/acdc12

Abstract ( 195 )

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For a many-atom battery coupled with a common thermal bath, the useful energy is maximized at an optimal number of the atoms for a fixed harmonic driving field, i.e., the so-called optimal building block [see Chang et al. New J. Phys. 23 103026 (2021)]. Here we consider the useful energy defined by the ergotropy and a continuous-wave driving field. For the single-atom case, we present analytical results of the increased energy and the ergotropy in the long-time limit (i.e., the steady-state ergotropy). It is found that there exists an optimal value of the driving-field strength. Such an observation holds for many-atom cases. Numerically, we show that the optimal strength increases linearly with the number N of the atoms. Using the optimal strength for each N, both the increased energy and the ergotropy increase monotonically with N.

Blind quantum computation with a client performing different single-qubit gates

Guang-Yang Wu(吴光阳), Zhen Yang(杨振), Yu-Zhan Yan(严玉瞻), Yuan-Mao Luo(罗元茂), Ming-Qiang Bai(柏明强), and Zhi-Wen Mo(莫智文)

Chin. Phys. B, 2023, 32 (11): 110302. DOI: 10.1088/1674-1056/ace15a

Abstract ( 180 )

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In the field of single-server blind quantum computation (BQC), a major focus is to make the client as classical as possible. To achieve this goal, we propose two single-server BQC protocols to achieve verifiable universal quantum computation. In these two protocols, the client only needs to perform either the gate T (in the first protocol) or the gates H and X (in the second protocol). With assistance from a single server, the client can utilize his quantum capabilities to generate some single-qubit states while keeping the actual state of these qubits confidential from others. By using these single-qubit states, the verifiable universal quantum computation can be achieved.

Deterministic remote preparation of multi-qubit equatorial states through dissipative channels

Liu-Yong Cheng(程留永), Shi-Feng Zhang(张世凤), Zuan Meng(孟钻), Hong-Fu Wang(王洪福), and Shou Zhang(张寿)

Chin. Phys. B, 2023, 32 (11): 110307. DOI: 10.1088/1674-1056/acdc0f

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We investigate the influence of a noisy environment on the remote preparation of the multi-qubit equatorial state, and specifically deduce the final states and fidelities of the remote preparation of the three-qubit and four-qubit equatorial states under diverse types of noisy environments, namely, amplitude damping, bit flip, phase damping, phase flip, bit-phase flip, depolarization, and non-Markov environments. The results show that when the decoherence factors of the front six noises are equal, the influence degrees of phase damped noise, bit flip noise, phase flip noise, and bit-phase flip noise are similar, while the information loss caused by the amplitude damped noise and depolarizing noise is less. In particular, the bit flip noise and depolarizing noise may have more complex effects on the remote state preparation (RSP) schemes depending on the phase information of the target states, even for the ideal cases where the fidelity values are always 1 for specific phase relations. In the non-Markov environment, owing to the back and forth of information between the environment and systems, fidelities exhibit oscillating behavior and the minimum value may stay greater than zero for a long evolutionary time. These results are expected to have potential applications for understanding and avoiding the influence of noise on remote quantum communication and quantum networks.

Optimal zero-crossing group selection method of the absolute gravimeter based on improved auto-regressive moving average model Suggested by editors

Zonglei Mou(牟宗磊), Xiao Han(韩笑), and Ruo Hu(胡若)

Chin. Phys. B, 2023, 32 (11): 110401. DOI: 10.1088/1674-1056/ace4b5

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An absolute gravimeter is a precision instrument for measuring gravitational acceleration, which plays an important role in earthquake monitoring, crustal deformation, national defense construction, etc. The frequency of laser interference fringes of an absolute gravimeter gradually increases with the fall time. Data are sparse in the early stage and dense in the late stage. The fitting accuracy of gravitational acceleration will be affected by least-squares fitting according to the fixed number of zero-crossing groups. In response to this problem, a method based on Fourier series fitting is proposed in this paper to calculate the zero-crossing point. The whole falling process is divided into five frequency bands using the Hilbert transformation. The multiplicative auto-regressive moving average model is then trained according to the number of optimal zero-crossing groups obtained by the honey badger algorithm. Through this model, the number of optimal zero-crossing groups determined in each segment is predicted by the least-squares fitting. The mean value of gravitational acceleration in each segment is then obtained. The method can improve the accuracy of gravitational measurement by more than 25% compared to the fixed zero-crossing groups method. It provides a new way to improve the measuring accuracy of an absolute gravimeter.

Quasi-synchronization of fractional-order complex networks with random coupling via quantized control

Hongwei Zhang(张红伟), Ran Cheng(程然), and Dawei Ding(丁大为)

Chin. Phys. B, 2023, 32 (11): 110501. DOI: 10.1088/1674-1056/acedf4

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We investigate the quasi-synchronization of fractional-order complex networks (FCNs) with random coupling via quantized control. Firstly, based on the logarithmic quantizer theory and the Lyapunov stability theory, a new quantized feedback controller, which can make all nodes of complex networks quasi-synchronization and eliminate the disturbance of random coupling in the system state, is designed under non-delay conditions. Secondly, we extend the theoretical results under non-delay conditions to time-varying delay conditions and design another form of quantization feedback controller to ensure that the network achieves quasi-synchronization. Furthermore, the error bound of quasi-synchronization is obtained. Finally, we verify the accuracy of our results using two numerical simulation examples.

Analysis of anomalous transport with temporal fractional transport equations in a bounded domain Suggested by editors

Kaibang Wu(吴凯邦), Jiayan Liu(刘嘉言), Shijie Liu(刘仕洁), Feng Wang(王丰), Lai Wei(魏来), Qibin Luan(栾其斌), and Zheng-Xiong Wang(王正汹)

Chin. Phys. B, 2023, 32 (11): 110502. DOI: 10.1088/1674-1056/acedf3

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Anomalous transport in magnetically confined plasmas is investigated using temporal fractional transport equations. The use of temporal fractional transport equations means that the order of the partial derivative with respect to time is a fraction. In this case, the Caputo fractional derivative relative to time is utilized, because it preserves the form of the initial conditions. A numerical calculation reveals that the fractional order of the temporal derivative α (α ∈ (0,1), sub-diffusive regime) controls the diffusion rate. The temporal fractional derivative is related to the fact that the evolution of a physical quantity is affected by its past history, depending on what are termed memory effects. The magnitude of α is a measure of such memory effects. When α decreases, so does the rate of particle diffusion due to memory effects. As a result, if a system initially has a density profile without a source, then the smaller the α is, the more slowly the density profile approaches zero. When a source is added, due to the balance of the diffusion and fueling processes, the system reaches a steady state and the density profile does not evolve. As α decreases, the time required for the system to reach a steady state increases. In magnetically confined plasmas, the temporal fractional transport model can be applied to off-axis heating processes. Moreover, it is found that the memory effects reduce the rate of energy conduction and hollow temperature profiles can be sustained for a longer time in sub-diffusion processes than in ordinary diffusion processes.

A discrete Boltzmann model with symmetric velocity discretization for compressible flow

Chuandong Lin(林传栋), Xiaopeng Sun(孙笑朋), Xianli Su(苏咸利),Huilin Lai(赖惠林), and Xiao Fang(方晓)

Chin. Phys. B, 2023, 32 (11): 110503. DOI: 10.1088/1674-1056/acea6b

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A discrete Boltzmann model (DBM) with symmetric velocity discretization is constructed for compressible systems with an adjustable specific heat ratio in the external force field. The proposed two-dimensional (2D) nine-velocity scheme has better spatial symmetry and numerical accuracy than the discretized velocity model in literature [Acta Aerodyn. Sin. 40 98108 (2022)] and owns higher computational efficiency than the one in literature [Phys. Rev. E 99 012142 (2019)]. In addition, the matrix inversion method is adopted to calculate the discrete equilibrium distribution function and force term, both of which satisfy nine independent kinetic moment relations. Moreover, the DBM could be used to study a few thermodynamic nonequilibrium effects beyond the Euler equations that are recovered from the kinetic model in the hydrodynamic limit via the Chapman-Enskog expansion. Finally, the present method is verified through typical numerical simulations, including the free-falling process, Sod's shock tube, sound wave, compressible Rayleigh-Taylor instability, and translational motion of a 2D fluid system.

Dynamic modelling and chaos control for a thin plate oscillator using Bubnov-Galerkin integral method

Xiaodong Jiao(焦晓东), Xinyu Wang(王新宇), Jin Tao(陶金), Hao Sun(孙昊) Qinglin Sun(孙青林), and Zengqiang Chen(陈增强)

Chin. Phys. B, 2023, 32 (11): 110504. DOI: 10.1088/1674-1056/ace822

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The utilization of thin plate systems based on acoustic vibration holds significant importance in micro-nano manipulation and the exploration of nonlinear science. This paper focuses on the analysis of an actual thin plate system driven by acoustic wave signals. By combining the mechanical analysis of thin plate microelements with the Bubnov-Galerkin integral method, the governing equation for the forced vibration of a square thin plate is derived. Notably, the reaction force of the thin plate vibration system is defined as f = α|w|, resembling Hooke's law. The energy function and energy level curve of the system are also analyzed. Subsequently, the amplitude-frequency response function of the thin plate oscillator is solved using the harmonic balance method. Through numerical simulations, the amplitude-frequency curves are analyzed for different vibration modes under the influence of various parameters. Furthermore, the paper demonstrates the occurrence of conservative chaotic motions in the thin plate oscillator using theoretical and numerical methods. Dynamics maps illustrating the system's states are presented to reveal the evolution laws of the system. By exploring the effects of force fields and system energy, the underlying mechanism of chaos is interpreted. Additionally, the phenomenon of chaos in the oscillator can be controlled through the method of velocity and displacement states feedback, which holds significance for engineering applications.

Dissipation and amplification management in an electrical model of microtubules: Hybrid behavior network

Sedric Ndoungalah, Guy Roger Deffo, Arnaud Djine, and Serge Bruno Yamgoué

Chin. Phys. B, 2023, 32 (11): 110505. DOI: 10.1088/1674-1056/acc44f

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The control of dissipation and amplification of solitary waves in an electrical model of a microtubule is demonstrated. This model consists of a shunt nonlinear resistance-capacitance (J(V)-C(V)) circuit and a series resistance-inductance (R-L) circuit. Through linear dispersion analysis, two features of the network are found, that is, low bandpass and bandpass filter characteristics. The effects of the conductance's parameter λ on the linear dispersion curve are also analyzed. It appears that an increase of λ induces a decrease (an increase) of the width of the bandpass filter for positive (negative) values of λ. By applying the reductive perturbation method, we derive the equation governing the dynamics of the modulated waves in the system. This equation is the well-known nonlinear Schrödinger equation extended by a linear term proportional to a hybrid parameter σ, i.e., a dissipation or amplification coefficient. Based on this parameter, we successfully demonstrate the hybrid behavior (dissipation and amplification) of the system. The exact and approximate solitary wave solutions of the obtained equation are derived, and the effects of the coefficient σ on the characteristic parameters of these waves are investigated. Using the analytical solutions found, we show numerically that the waves that are propagated throughout the system can be dissipated, amplified, or remain stable depending on the network parameters. These results are not only in agreement with the analytical predictions, but also with the existing experimental results in the literature.

Detection of EEG signals in normal and epileptic seizures with multiscale multifractal analysis approach via weighted horizontal visibility graph Suggested by editors

Lu Ma(马璐), Yan-Lin Ren(任彦霖), Ai-Jun He(何爱军), De-Qiang Cheng(程德强), and Xiao-Dong Yang(杨小冬)

Chin. Phys. B, 2023, 32 (11): 110506. DOI: 10.1088/1674-1056/acdfbf

Abstract ( 146 )

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Electroencephalogram (EEG) signals contain important information about the regulation of brain system. Thus, automatic detection of epilepsy by analyzing the characteristics obtained from EEG signals has important research implications in the field of clinical medicine. In this paper, the horizontal visibility graph (HVG) algorithm is used to map multifractal EEG signals into complex networks. Then, we study the structure of the networks and explore the nonlinear dynamics properties of the EEG signals inherited from these networks. In order to better describe complex brain behaviors, we use the angle between two connected nodes as the edge weight of the network and construct the weighted horizontal visibility graph (WHVG). In our studies, fractality and multifractality of WHVG are innovatively used to analyze the structure of related networks. However, these methods only analyze the reconstructed dynamical system in general characterizations, they are not sufficient to describe the complex behavior and cannot provide a comprehensive picture of the system. To this effect, we propose an improved multiscale multifractal analysis (MMA) for network, which extends the description of the network dynamics features by focusing on the relationship between the multifractality and the measured scale-free intervals. Furthermore, neural networks are applied to train the above-mentioned parameters for the classification and identification of three kinds of EEG signals, i.e., health, interictal phase, and ictal phase. By evaluating our experimental results, the classification accuracy is 99.0%, reflecting the effectiveness of the WHVG algorithm in extracting the potential dynamic characteristics of EEG signals.

Role of excited states in helium-like ions on high-order harmonic generation

Jiang-Hua Luo(罗江华) and Jia-Jun Xiao(肖佳俊)

Chin. Phys. B, 2023, 32 (11): 113201. DOI: 10.1088/1674-1056/ace317

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We theoretically investigate high-order harmonic generation (HHG) of helium (He), lithium cation (Li⁺), and beryllium dication (Be²⁺) using the time-dependent Hartree-Fock method to solve the three-dimensional time-dependent Schrödinger equation. It is found that the intensity of the HHG increases significantly from a certain harmonic order below the ionization threshold, and the initial position of the enhancement does not depend on the intensity or the wavelength of the driving laser field. Further analysis shows that excited states play an important role on this enhancement, consistent with the excited-state tunneling mechanism [Phys. Rev. Lett. 116 123901 (2016)]. Our results unambiguously show that excited-state tunneling is essential for understanding the enhancement of HHG. Accordingly, a four-step model is herein proposed to illustrate the multiphoton excitation effect in helium-like ions, which enriches the physics of HHG enhancement.

Structure study of a dielectric laser accelerator with discrete translational symmetry Suggested by editors

Yangfan He(何阳帆), Bin Sun(孙斌), Mingjiang Ma(马铭江), Wei Li(李伟), Zhihao Cui(崔志浩), and Zongqing Zhao(赵宗清)

Chin. Phys. B, 2023, 32 (11): 114101. DOI: 10.1088/1674-1056/acc05a

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The dielectric laser accelerator (DLA) is a promising technology for achieving high-gradient acceleration in a compact design. Its advantages include ease of cascading and an energy gain per unit distance which can exceed that of conventional accelerators by two orders of magnitude. This paper establishes rules for efficient particle acceleration using dielectric structures based on basic equations, proposes a design principle for DLA structures with clear physical images and verifies the accuracy of the corresponding formula for energy gain. DLA structures with different specifications, materials and geometric shapes are constructed, and the achievable acceleration gradient is calculated. Our results demonstrate that effective acceleration can be achieved when the electric field sensed by particles in the acceleration cavity has zero frequency, which provides a powerful method for designing such devices. Furthermore, we demonstrate that the simplified formula for calculating energy gain presented in this paper can accurately determine the energy gain of particles during the design of acceleration structures using a dielectric accelerator.

Optical chirality induced by spin-orbit interaction of light in a tightly focused Laguerre-Gaussian beam

Mingchao Zhu(朱明超), Shenggui Fu(付圣贵), and Zhongsheng Man(满忠胜)

Chin. Phys. B, 2023, 32 (11): 114202. DOI: 10.1088/1674-1056/acefc9

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Optical chirality is one of the important and fundamental dynamic properties of light besides energy, momentum, and angular momentum. The quantification of electromagnetic chirality has been conceptualized only recently. Now, it is well known that for paraxial plane waves of light, the optical chirality is proportional to the ellipticity of the polarization ellipse, i.e., completely independent of the phase distribution. Here it is shown that optical vortex and state of polarization of the source paraxial field both have contributions to the optical chirality of the nonparaxial field generated by tightly focused Laguerre-Gaussian (LG) beam, which is in Stark contrast to the paraxial plane wave of light known from classical optics. The physical reason is the redistribution of local electromagnetic polarization in three dimensions associated with spin-orbit interaction.

Optical image encryption algorithm based on a new four-dimensional memristive hyperchaotic system and compressed sensing

Yang Du(都洋), Guoqiang Long(隆国强), Donghua Jiang(蒋东华), Xiuli Chai(柴秀丽), and Junhe Han(韩俊鹤)

Chin. Phys. B, 2023, 32 (11): 114203. DOI: 10.1088/1674-1056/acef08

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Some existing image encryption schemes use simple low-dimensional chaotic systems, which makes the algorithms insecure and vulnerable to brute force attacks and cracking. Some algorithms have issues such as weak correlation with plaintext images, poor image reconstruction quality, and low efficiency in transmission and storage. To solve these issues, this paper proposes an optical image encryption algorithm based on a new four-dimensional memristive hyperchaotic system (4D MHS) and compressed sensing (CS). Firstly, this paper proposes a new 4D MHS, which has larger key space, richer dynamic behavior, and more complex hyperchaotic characteristics. The introduction of CS can reduce the image size and the transmission burden of hardware devices. The introduction of double random phase encoding (DRPE) enables this algorithm has the ability of parallel data processing and multi-dimensional coding space, and the hyperchaotic characteristics of 4D MHS make up for the nonlinear deficiency of DRPE. Secondly, a construction method of the deterministic chaotic measurement matrix (DCMM) is proposed. Using DCMM can not only save a lot of transmission bandwidth and storage space, but also ensure good quality of reconstructed images. Thirdly, the confusion method and diffusion method proposed are related to plaintext images, which require both four hyperchaotic sequences of 4D MHS and row and column keys based on plaintext images. The generation process of hyperchaotic sequences is closely related to the hash value of plaintext images. Therefore, this algorithm has high sensitivity to plaintext images. The experimental testing and comparative analysis results show that proposed algorithm has good security and effectiveness.

Single exposure passive three-dimensional information reconstruction based on an ordinary imaging system

Shen-Cheng Dou(窦申成), Fan Liu(刘璠), Hu Li(李虎), Xu-Ri Yao(姚旭日), Xue-Feng Liu(刘雪峰), and Guang-Jie Zhai(翟光杰)

Chin. Phys. B, 2023, 32 (11): 114204. DOI: 10.1088/1674-1056/ace764

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Existing three-dimensional (3D) imaging technologies have issues such as requiring active illumination, multiple exposures, or coding modulation. We propose a passive single 3D imaging method based on an ordinary imaging system. Using the point spread function of the imaging system to realize the non-coding measurement on the target, the full-focus images and depth information of the 3D target can be extracted from a single two-dimensional (2D) image through the compressed sensing algorithm. Simulation and experiments show that this approach can complete passive 3D imaging based on an ordinary imaging system without any coding operations. This method can achieve millimeter-level vertical resolution under single exposure conditions and has the potential for real-time dynamic 3D imaging. It improves the efficiency of 3D information detection, reduces the complexity of the imaging system, and may be of considerable value to the field of computer vision and other related applications.

Electromagnetically induced transparency via localized surface plasmon mode-assisted hybrid cavity QED

Xiaomiao Li(李晓苗), Famin Liu(刘发民), Zigeng Li(李子更), Hongyan Zhu(朱虹燕), Fan Wang(王帆), and Xiaolan Zhong(钟晓岚)

Chin. Phys. B, 2023, 32 (11): 114205. DOI: 10.1088/1674-1056/acd7d2

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In recent years, most studies have focused on the perfect absorption and high-efficiency quantum memory of the one-sided system, ignoring the characteristics of its optical switching contrast. Thus, the performance of all-optical switching and optical transistors is limited. Herein, we propose a localized surface plasmon (LSP) mode-assisted cavity QED system which consists of a Λ-shaped three-level quantum emitter (QE), a metal nanoparticle and a one-sided optical cavity with a fully reflected mirror. In this system, the QE coherently couples to the cavity and LSP mode respectively, which is manipulated by the control field. As a result, considerably high and stable switch contrast of 90% can be achievable due to the strong confined field of the LSP mode and perfect absorption of the optical medium. In addition, we obtain a power dependent effect between the control field and the transmitted frequency as a result of the converted dark state. We employ the Heisenberg-Langevin equation and numerical master equation formalisms to explain high switching, controllable output light and the dark state. Our system introduces an effective method to improve the performance of optical switches based on the one-sided system in quantum information storage and quantum communication.

Large spatial shifts of reflected light beam off biaxial hyperbolic materials

Jia-Guo Shen(沈加国), Syed-ul-hasnain Bakhtiar(哈思内恩), Hao-Yuan Song(宋浩元), Sheng Zhou(周胜), Shu-Fang Fu(付淑芳), Xuan-Zhang Wang(王选章), Xuan Wang(王暄), and Qiang Zhang(张强)

Chin. Phys. B, 2023, 32 (11): 114206. DOI: 10.1088/1674-1056/acd526

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Many optical systems that deal with polarization rely on the adaptability of controlling light reflection in the lithography-free nanostructure. In this study, we explore the Goos-Hänchen (GH) shift and Imbert-Fedorov (IF) shift in a biaxial hyperbolic film on a uniaxial hyperbolic substrate. This research statistically calculates and analyzes the GH shift and IF shift for the natural biaxial hyperbolic material (NBHM). We select the surface with the strongest anisotropy within the NBHM and obtain the complex beam-shift spectrum. By incorporating the NBHM film, the GH shift caused by a transversely magnetic incident-beam on the surface increases significantly compared with that on the uniaxial hyperbolic material. The maximum of GH shift can reach 86λ₀ at about 841 cm^-1 when the thickness of NBHM is 90 nm, and the IF shift can approach 2.7λ₀ for a circularly-polarized beam incident on a 1700-nm-thick NBHM. It is found that the spatial-shift increases when a highly anisotropic hyperbolic polariton is excited in hyperbolic material, where the shift spectrum exhibits an oscillating behaviour accompanied with sharp shift peak (steep slope). This large spatial shift may provide an alternative strategy to develop novel sub-micrometric optical devices and biosensors.

High-power xenon lamp-pumped Er:YAP pulse laser operated in free-running and acousto-optical Q-switching modes

Cong Quan(权聪), Dunlu Sun(孙敦陆), Huili Zhang(张会丽), Jianqiao Luo(罗建乔), Zhiyuan Han(韩志远), Yang Qiao(乔阳), Yuwei Chen(陈玙威), Zhentao Wang(王镇涛), Maojie Cheng(程毛杰), and Qingli Zhang(张庆礼)

Chin. Phys. B, 2023, 32 (11): 114207. DOI: 10.1088/1674-1056/ace8f7

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We demonstrate a high-energy and high-power pulse laser on a xenon lamp-pumped Er:YAP crystal. The laser performance and thermal focal lengths under different working frequencies are discussed. The results show that the thermal lens effect is gradually aggravated with the increase of working frequencies, and even working at 100 Hz, a single pulse energy of 234 mJ can be achieved. A maximum average power of 41.5 W is achieved with a working frequency of 20 Hz and slope efficiency of 2.82%. This output power is much higher than other xenon lamp-pumped erbium laser devices. A Q-switched laser is demonstrated by using the TeO₂ crystal, the maximum output energies of 11.5 mJ and 3.5 mJ are obtained at 50 and 100 Hz, the corresponding peak powers are 93.4 kW and 17.2 kW, respectively. The laser wavelengths and beam quality factors are also characterized in the free-running and Q-switched modes. A higher pulse energy and peak power laser could be achieved further by improving the damage threshold of TeO₂ acousto-optical Q-switching. All the experimental results illustrate that the xenon lamp-pumped Er:YAP laser is a promising candidate for high-power and high-frequency mid-infrared laser devices.

Comprehensive analysis of pure-quartic soliton dynamics in a passively mode-locked fiber laser

Lie Liu(刘列), Ying Han(韩颖), Jiayu Huo(霍佳雨), Honglin Wen(文红琳), Ge Wu(吴戈), and Bo Gao(高博)

Chin. Phys. B, 2023, 32 (11): 114209. DOI: 10.1088/1674-1056/acc451

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The understanding of soliton dynamics promotes the development of ultrafast laser technology. High-energy pure-quartic solitons (PQSs) have gradually become a hotspot in recent years. Herein, we numerically study the influence of the gain bandwidth, saturation power, small-signal gain, and output coupler on PQS dynamics in passively mode-locked fiber lasers. The results show that the above four parameters can affect PQS dynamics. Pulsating PQSs occur as we alter the other three parameters when the gain bandwidth is 50 nm. Meanwhile, PQSs evolve from pulsating to erupting and then to splitting as the other three parameters are altered when the gain bandwidth is 10 nm, which can be attributed to the existence of the spectral filtering effect and intra-cavity fourth-order dispersion. These findings provide new insights into PQS dynamics in passively mode-locked fiber lasers.

Terahertz shaping technology based on coherent beam combining

Xiao-Ran Zheng(郑晓冉), Dan-Ni Ma(马丹妮), Guang-Tong Jiang(蒋广通), Cun-Lin Zhang(张存林), and Liang-Liang Zhang(张亮亮)

Chin. Phys. B, 2023, 32 (11): 114210. DOI: 10.1088/1674-1056/acc2b0

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The generation of terahertz (THz) waves by focusing a femtosecond pulsed laser beam at a distance is able to overcome the strong absorption properties of air and has rapidly attracted the attention of industry. However, the poor directionality of the THz wave radiation generated by this method is not conducive to THz wave applications. By controlling the morphology of the ultrafast laser-excited plasma filament and its electron density distribution through coherent beam combining technology, we achieve direct THz beam shaping and are able to obtain THz wave radiation of Gaussian or arbitrary transverse distribution. The novel experimental approach proposed in this paper opens up the research field of direct THz wave shaping using plasma. Moreover, it innovates multi-parameter convergence algorithms and, by doing so, has the potential to find beam patterns with higher energy conversion efficiency and break the energy limit of THz waves emitted by lasers at high power.

Direct Kerr-lens mode-locked Tm:LuYO₃ ceramic laser

Weijun Ling(令维军), Jingwen Xue(薛婧雯), Jinfang Yang(杨金芳) Chong Wang(王翀), Xiaojuan Du(杜晓娟), Wenting Wang(王文婷), Mingxia Zhang(张明霞), Feiping Lu(路飞平), Xiangbing Li(李向兵), and Zhong Dong(董忠)

Chin. Phys. B, 2023, 32 (11): 114211. DOI: 10.1088/1674-1056/acc7ff

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A direct Kerr-lens mode-locked Tm:LuYO₃ ceramic laser without the aid of any mode-locked starting element is reported for the first time. A pulse duration as short as 259 fs and a maximum average output power of 326 mW are obtained at a repetition rate of 97.1 MHz. The corresponding optical spectrum centered at 2053 nm exhibits a bandwidth of 19.8 nm, which indicates the presence of nearly Fourier transform-limited pulses. Such a Kerr-lens mode-locked Tm:LuYO₃ ceramic laser is a promising ultrashort pulse source, with both the excellent laser characteristics of Tm:LuYO₃ and the high-power 790 nm laser diode pumping scheme.

Preparation and cooling performance analysis of double-layer radiative cooling hybrid coatings with TiO₂/SiO₂/Si₃N₄ micron particles

Yang-Chun Zhao(赵洋春) and Yong-Min Zhou(周勇敏)

Chin. Phys. B, 2023, 32 (11): 114401. DOI: 10.1088/1674-1056/acdac0

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Passive daytime radiative cooling is achieved by radiating heat into outer space through electromagnetic waves without energy consumption. A scalable double-layer coating with a mixture of TiO₂, SiO₂, and Si₃N₄ micron particles for radiative cooling is proposed in this study. The finite-difference time-domain algorithm is used to analyze the influence of particle size and coating thickness on radiative cooling performance. The results of the simulation show that the particle size of 3 μ can give the best cooling performance, and the coating thickness should be above 25 μ m for SiO₂ coating. Meanwhile, the mixture of SiO₂ and Si₃N₄ significantly improves the overall emissivity. Through sample preparation and characterization, the mixture coating with a 1:1 ratio addition on an Al substrate exhibits high reflectivity with a value of 87.6% in the solar spectrum, and an average emissivity of 92% in the infrared region (2.5 μ m-15 μ m), which can be attributed to the synergy among the optical properties of the material. Both coatings can theoretically be cooled by about 8 °C during the day and about 21 °C at nighttime with h_c=4 W·m^-2·K^-1. Furthermore, even considering the significant conduction and convection exchanges, the cooling effect persists. Outdoor experimental results show that the temperature of the double-layer radiative cooling coating is always lower than the ambient temperature under direct sunlight during the day, and can be cooled by about 5 °C on average, while lower than the temperature of the aluminum film by almost 12 °C.

Effect of local wall temperature on hypersonic boundary layer stability and transition

Ruiyang Lu(鲁锐洋) and Zhangfeng Huang(黄章峰)

Chin. Phys. B, 2023, 32 (11): 114701. DOI: 10.1088/1674-1056/acea69

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Wall temperature significantly affects stability and receptivity of the boundary layer. Changing the wall temperature locally may therefore be an effective laminar flow control technique. However, the situation is complicated when the wall temperature distribution is nonuniform, and researchers have experimentally found that local wall cooling may delay the onset of transition. We attempt to clarify the physical mechanisms whereby the local wall temperature affects the transition and the stability of a hypersonic boundary layer. A numerical investigation of the disturbance evolution in a Mach-6 sharp cone boundary layer with local wall heating or cooling is conducted. Direct numerical simulation (DNS) is performed for the single-frequency and broadband disturbance evolution caused by random forcing. We vary the local wall temperature and the location of heating/cooling, and then use the e^N method to estimate the transition onset. Our results show that local wall cooling amplifies high-frequency unstable waves while stabilizing low-frequency unstable waves, with local heating amplifying all unstable waves locally. The disturbance amplitude and second-mode peak frequency obtained by DNS agree well with the previous experimental results. Local cooling/heating has a dual effect on the stability of the hypersonic boundary layer. For local cooling, while it effectively inhibits the growth of the low-frequency unstable waves that dominate the transition downstream, it also further destabilizes the downstream flow. In addition, while upstream cooling can delay the transition, excessive cooling may promote it; local heating always slightly promotes the transition. Finally, recommendations are given for practical engineering applications based on the present results.

Computational and experimental investigations of a microfluidic mixer for efficient iodine extraction using carbon tetrachloride enhanced with gas bubbles

Siddique Muhammad Kashif, Sun Lin(孙林), and Li Songjing(李松晶)

Chin. Phys. B, 2023, 32 (11): 114702. DOI: 10.1088/1674-1056/acf03f

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Numerous studies have been conducted on microfluidic mixers in various microanalysis systems, which elucidated the manipulation and control of small fluid volumes within microfluidic chips. These studies have demonstrated the ability to control fluids and samples precisely at the microscale. Microfluidic mixers provide high sensitivity for biochemical analysis due to their small volumes and high surface-to-volume ratios. A promising approach in drug delivery is the rapid microfluidic mixer-based extraction of elemental iodine at the micro level, demonstrating the versatility and the potential to enhance diagnostic imaging and accuracy in targeted drug delivery. Micro-mixing inside microfluidic chips plays a key role in biochemical analysis. The experimental study describes a microfluidic mixer for extraction of elemental iodine using carbon tetrachloride with a gas bubble mixing process. Gas bubbles are generated inside the microcavity to create turbulence and micro-vortices resulting in uniform mixing of samples. The bubble mixing of biochemical samples is analyzed at various pressure levels to validate the simulated results in computational fluid dynamics (CFD). The experimental setup includes a high-resolution camera and an air pump to observe the mixing process and volume at different pressure levels with time. The bubble formation is controlled by adjusting the inert gas flow inside the microfluidic chip. Microfluidic chip-based gas bubble mixing effects have been elaborated at various supplied pressures.

Simulation of gas-liquid two-phase flow in a flow-focusing microchannel with the lattice Boltzmann method

Kai Feng(冯凯), Gang Yang(杨刚), and Huichen Zhang(张会臣)

Chin. Phys. B, 2023, 32 (11): 114703. DOI: 10.1088/1674-1056/acea6e

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A lattice Boltzmann method for gas-liquid two-phase flow involving non-Newtonian fluids is developed. Bubble formation in a flow-focusing microchannel is simulated by the method. The influences of flow rate ratio, surface tension, wetting properties, and rheological characteristics of the fluid on the two-phase flow are analyzed. The results indicate that the flow pattern transfers from slug flow to dry-plug flow with a sufficiently small capillary number. Due to the presence of three-phase contact lines, the contact angle has a more significant effect on the dry-plug flow pattern than on the slug flow pattern. The deformation of the front and rear meniscus of a bubble in the shear-thinning fluid can be explained by the variation of the capillary number. The reduced viscosity and increased contact angle are beneficial for the drag reduction in a microchannel. It also demonstrates the effectiveness of the current method to simulate the gas-liquid two-phase flow in a microchannel.

Compared discharge characteristics and film modifications of atmospheric pressure plasma jets with two different electrode geometries

Xiong Chen(陈雄), Xing-Quan Wang(王兴权), Bin-Xiang Zhang(张彬祥), Ming Yuan(袁明), and Si-Ze Yang(杨思泽)

Chin. Phys. B, 2023, 32 (11): 115201. DOI: 10.1088/1674-1056/ace768

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Atmospheric pressure plasma jet shows great potential for polymer film processing. The electrode geometry is the key factor to determine discharge characteristics and film modification of jets. In this paper, we compared the discharge characteristics and the film modifications of atmospheric pressure plasma jets with needle-ring electrode (NRE) and double-ring electrode (DRE). The results show that jet with NRE has stronger electric field intensity and higher discharge power, making it present more reactive oxygen particles and higher electron temperature, but its discharge stability is insufficient. In contrast, the jet with DRE has uniform electric field distribution of lower field intensity, which allows it to maintain stable discharge over a wide range of applied voltages. Besides, the modification results show that the treatment efficiency of PET film by NRE is higher than that by DRE. These results provide a suitable atmospheric pressure plasma jets device selection scheme for polymer film processing process.

Structural origin for composition-dependent nearest atomic distance in Cu-Zr metallic glass

Chi Zhang(张驰), Hua-Shan Liu(刘华山), and Hai-Long Peng(彭海龙)

Chin. Phys. B, 2023, 32 (11): 116101. DOI: 10.1088/1674-1056/acce99

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We systematically investigate the structures of Cu-Zr metallic glass (MG) by varying the Cu concentration in classic molecular-dynamics simulation. From the pair distribution functions (PDFs), it is found that the nearest atomic distance between Zr atom and Zr atom increases significantly after adding Cu, which is related to the composition-dependent coordination behavior between Cu atom and Zr atom in the nearest neighbors. The portion of PDF related to the nearest connection is decomposed into the contributions from quadrilateral structure, pentagonal structure, hexagonal structure, and heptagonal bipyramid structure. Although the population of denser structures, i.e. 5-, 6-, and 7-number sharing ones, increases with Cu addition increasing, the connection distances between the central atoms in all these bipyramids increase for Zr-Zr pairs, leading to the expansion of Zr-Zr nearest atomic distance. These results unveil the effect of the interplay between chemical interaction and geometric packing on the atomic-level structure in Cu-Zr metallic glasses.

A group of ductile metallic glasses prepared by modifying local structure of icosahedral quasicrystals Suggested by editors

Qi Qiao(乔琪), Ji Wang(王吉), Zhengqing Cai(蔡正清), Shidong Feng(冯士东), Zhenqiang Song(宋贞强), Benke Huo(霍本科), Zijing Li(李子敬), and Li-Min Wang(王利民)

Chin. Phys. B, 2023, 32 (11): 116401. DOI: 10.1088/1674-1056/ace823

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Inspired by research into the association between icosahedral local orders and the plasticity of metallic glasses (MGs), beryllium (Be) is added to the icosahedral quasi-crystal forming alloy Zr₄₀Ti₄₀Ni₂₀. In this way, bulk metallic glasses (BMGs) with favorable compressive plasticity are fabricated. Therein, the icosahedral quasi-crystalline phase is the main competing phase of amorphous phases and icosahedral local orders are the main local atomic motifs in amorphous phases. The alloys of (Zr₄₀Ti₄₀Ni₂₀)₇₆Be₂₄ and (Zr₄₀Ti₄₀Ni₂₀)₇₂Be₂₈ with their greater plastic strain capacity show similar characteristics to highly plastic amorphous systems: The serrated flow of compression curves always follows a near-exponential distribution. The primary and secondary shear bands intersect each other, bifurcate, and bend. Typical vein patterns are densely distributed on the fracture surfaces. The relaxation enthalpy of four MGs is linearly correlated with the plastic strain, that is, the greater the relaxation enthalpy, the larger the plastic strain.

Spontaneous isospin polarization and quantum Hall ferromagnetism in a rhombohedral trilayer graphene superlattice ^Hot!

Xiangyan Han(韩香岩), Qianling Liu(刘倩伶), Ruirui Niu(牛锐锐), Zhuangzhuang Qu(曲壮壮), Zhiyu Wang(王知雨), Zhuoxian Li(李卓贤), Chunrui Han(韩春蕊), Kenji Watanabe, Takashi Taniguchi, Zizhao Gan(甘子钊), and Jianming Lu(路建明)

Chin. Phys. B, 2023, 32 (11): 117201. DOI: 10.1088/1674-1056/acddcf

Abstract ( 225 )

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Moiré superlattices in van der Waals heterostructures have recently attracted enormous interests, due to the highly controllable electronic correlation that gives rise to superconductivity, ferromagnetism, and nontrivial topological properties. To gain a deep understanding of such exotic properties, it is essential to clarify the broken symmetry between spin and valley flavors which universally exists in these ground states. Here in a rhombohedral trilayer graphene crystallographically aligned with a hexagonal boron nitride, we report various kinds of symmetry-breaking transition tuned by displacement fields (D) and magnetic fields: (i) While it is well known that a finite D can enhance correlation to result in correlated insulators at fractional fillings of a flat band, we find the correlation gap emerges before the flavor is fully filled at a positive D, but the sequence is reversed at a negative D. (ii) Around zero D, electronic correlation can be invoked by narrow Landau levels, leading to quantum Hall ferromagnetism that lifts all the degeneracies including not only spin and valley but also orbital degrees of freedom. Our result unveils the complication of transitions between symmetry-breaking phases, shedding light on the mechanisms of various exotic phenomena in strongly correlated systems.

Simulation of optical and electrical synaptic functions in MoS₂/α-In₂Se₃ heterojunction memtransistors

Tao Xiang(相韬), Fengxiang Chen(陈凤翔), Xiaoli Li(李晓莉),Xiaodong Wang(王小东), Yuling Yan(闫誉玲), and Lisheng Wang(汪礼胜)

Chin. Phys. B, 2023, 32 (11): 117301. DOI: 10.1088/1674-1056/acee58

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Memtransistors combine memristors and field-effect transistors, which can introduce multi-port control and have significant applications for enriching storage methods. In this paper, multilayer α-In₂Se₃ and MoS₂ were transferred to the substrate by the mechanical exfoliation method, then a heterojunction MoS₂/α-In₂Se₃ memtransistor was prepared. Neural synaptic simulations were performed using electrical and optical pulses as input signals. Through measurements, such as excitatory/inhibitory post-synaptic current (EPSC/IPSC), long-term potentiation/depression (LTP/LTD), and paired-pulse facilitation/depression (PPF/PPD), it can be found that the fabricated device could simulate various functions of neural synapses well, and could work as an electronic synapse in artificial neural networks, proposing a possible solution for neuromorphic storage and computation.

Low-damage interface enhancement-mode AlN/GaN high electron mobility transistors with 41.6% PAE at 30 GHz

Si-Yu Liu(刘思雨), Jie-Jie Zhu(祝杰杰), Jing-Shu Guo(郭静姝), Kai Cheng(程凯), Min-Han Mi(宓珉瀚), Ling-Jie Qin(秦灵洁), Bo-Wen Zhang(张博文), Min Tang(唐旻), and Xiao-Hua Ma(马晓华)

Chin. Phys. B, 2023, 32 (11): 117302. DOI: 10.1088/1674-1056/acd8a5

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This paper reports a low-damage interface treatment process for AlN/GaN high electron mobility transistor (HEMT) and demonstrates the excellent power characteristics of radio-frequency (RF) enhancementmode (E-mode) AlN/GaN HEMT. An RF E-mode device with 2.9-nm-thick AlN barrier layer fabricated by remote plasma oxidation (RPO) treatment at 300 °C. The device with a gate length of 0.12-μ m has a threshold voltage (V_th) of 0.5 V, a maximum saturation current of 1.16 A/mm, a high I_on/I_off ratio of 1× 10⁸, and a 440-mS/mm peak transconductance. During continuous wave (CW) power testing, the device demonstrates that at 3.6 GHz, a power added efficiency is 61.9% and a power density is 1.38 W/mm, and at 30 GHz, a power added efficiency is 41.6% and a power density is 0.85 W/mm. Furthermore, the RPO treatment improves the mobility of RF E-mode AlN/GaN HEMT. All results show that the RPO processing method has good applicability to scaling ultrathin barrier E-mode AlN/GaN HEMT for 5G compliable frequency ranging from sub-6 GHz to Ka-band.

Structure, magnetism and magnetocaloric effects in Er₅Si₃B_x (x=0.3, 0.6) compounds

Zhihong Hao(郝志红), Hui Liu(刘辉), and Juguo Zhang(张聚国)

Chin. Phys. B, 2023, 32 (11): 117501. DOI: 10.1088/1674-1056/ace684

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We investigate the structure, magnetic properties, magnetic phase transitions and magnetocaloric effects (MCEs) of Er₅Si₃B_x (x=0.3, 0.6) compounds. The Er₅Si₃B_x (x=0.3, 0.6) compounds crystalize in a Mn₅Si₃ type hexagonal structure (space group: P63/cm) and exhibit a successive complicated magnetic phase transition. The extensive magnetic phase transitions contribute to the broad temperature range of MCEs exhibiting in Er₅Si₃B_x (x=0.3, 0.6) compounds, with maximum magnetic entropy change (-ΔS_M^max) and refrigeration capacity of 10.2 J·kg^-1·K^-1, 356.3 J/kg and 11.5 J·kg^-1·K^-1, 393.3 J/kg under varying magnetic fields 0-5 T, respectively. Remarkably, the δT_FWHM values (the temperature range corresponding to 1/2×|-ΔS_M^max|) of Er₅Si₃B_x (x=0.3, 0.6) compounds were up to 41.8 K and 39.6 K, respectively. Thus, the present work provides a potential magnetic refrigeration material with a broad temperature range MCEs for applications in cryogenic magnetic refrigerators.

Investigation of magnetization reversal and domain structures in perpendicular synthetic antiferromagnets by first-order reversal curves and magneto-optical Kerr effect

Xiang-Qian Wang(王向谦), Jia-Nan Li(李佳楠), Kai-Zhou He(何开宙),Ming-Ling Xie(谢明玲), and Xu-Peng Zhu(朱旭鹏)

Chin. Phys. B, 2023, 32 (11): 117502. DOI: 10.1088/1674-1056/acd8aa

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Perpendicular synthetic-antiferromagnet (p-SAF) has broad applications in spin-transfer-torque magnetic random access memory and magnetic sensors. In this study, the p-SAF films consisting of (Co/Ni)₃]/Ir(t_Ir)/[(Ni/Co)₃ are fabricated by magnetron sputtering technology. We study the domain structure and switching field distribution in p-SAF by changing the thickness of the infrared space layer. The strongest exchange coupling field (H_ex) is observed when the thickness of Ir layer (t_Ir) is 0.7 nm and becoming weak according to the Ruderman-Kittel-Kasuya-Yosida-type coupling at 1.05 nm, 2.1 nm, 4.55 nm, and 4.9 nm in sequence. Furthermore, the domain switching process between the upper Co/Ni stack and the bottom Co/Ni stack is different because of the antiferromagnet coupling. Compared with ferromagnet coupling films, the antiferromagnet samples possess three irreversible reversal regions in the first-order reversal curve distribution. With t_Ir increasing, these irreversible reversal regions become denser and smaller. The results from this study will help us understand the details of the magnetization reversal process in the p-SAF.

In-plane spin excitation of skyrmion bags Suggested by editors

Shuang Li(李爽), Ke-Xin Li(李可欣), Zhao-Hua Liu(刘照华), Qi-Yuan Zhu(朱起源), Chen-Bo Zhao(赵晨博), Hu Zhang(张虎), Xing-Qiang Shi(石兴强), Jiang-Long Wang(王江龙), Rui-Ning Wang(王瑞宁), Ru-Qian Lian(连如乾), Peng-Lai Gong(巩朋来), and Chen-Dong Jin(金晨东)

Chin. Phys. B, 2023, 32 (11): 117503. DOI: 10.1088/1674-1056/acd327

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Skyrmion bags are spin structures with arbitrary topological charges, each of which is composed of a big skyrmion and several small skyrmions. In this work, by using an in-plane alternating current (AC) magnetic field, we investigate the spin-wave modes of skyrmion bags, which behave differently from the clockwise (CW) rotation mode and the counterclockwise (CCW) rotation mode of skyrmions because of their complex spin topological structures. The in-plane excitation power spectral density shows that each skyrmion bag possesses four resonance frequencies. By further studying the spin dynamics of a skyrmion bag at each resonance frequency, the four spin-wave modes, i.e., a CCW-CW mode, two CW-breathing modes with different resonance strengths, and an inner CCW mode, appear as a composition mode of outer skyrmion-inner skyrmions. Our results are helpful in understanding the in-plane spin excitation of skyrmion bags, which may contribute to the characterization and detection of skyrmion bags, as well as the applications in logic devices.

Facile integration of an Al-rich Al_1-xIn_xN photodetector on free-standing GaN by radio-frequency magnetron sputtering

Xinke Liu(刘新科), Zhichen Lin(林之晨), Yuheng Lin(林钰恒), Jianjin Chen(陈建金), Ping Zou(邹苹), Jie Zhou(周杰), Bo Li(李博), Longhai Shen(沈龙海), Deliang Zhu(朱德亮), Qiang Liu(刘强), Wenjie Yu(俞文杰), Xiaohua Li(黎晓华), Hong Gu(顾泓), Xinzhong Wang(王新中), and Shuangwu Huang(黄双武)

Chin. Phys. B, 2023, 32 (11): 117701. DOI: 10.1088/1674-1056/acbf25

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Al_1-xIn_xN, a III-nitride semiconductor material, is currently of great research interest due to its remarkable physical properties and chemical stability. When the Al and In compositions are tuned, its band-gap energy varies from 0.7 eV to 6.2 eV, which shows great potential for application in photodetectors. Here, we report the fabrication and performance evaluation of integrated Al_1-xIn_xN on a free-standing GaN substrate through direct radio-frequency magnetron sputtering. The optical properties of Al_1-xIn_xN will be enhanced by the polarization effect of a heterostructure composed of Al_1-xIn_xN and other III-nitride materials. An Al_1-xIn_xN/GaN visible-light photodetector was prepared by semiconductor fabrication technologies such as lithography and metal deposition. The highest photoresponsivity achieved was 1.52 A·W^-1 under 365 nm wavelength illumination and the photodetector was determined to have the composition Al_0.75In_0.25N/GaN. A rise time of 0.55 s was observed after transient analysis of the device. The prepared Al_1-xIn_xN visible-light photodetector had a low dark current, high photoresponsivity and fast response speed. By promoting a low-cost, simple fabrication method, this study expands the application of ternary alloy Al_1-xIn_xN visible-light photodetectors in optical communication.

Unveiling localized electronic properties of ReS₂ thin layers at nanoscale using Kelvin force probe microscopy combined with tip-enhanced Raman spectroscopy

Yu Luo(罗宇), Weitao Su(苏伟涛), Juanjuan Zhang(张娟娟), Fei Chen(陈飞), Ke Wu(武可), Yijie Zeng(曾宜杰), and Hongwei Lu(卢红伟)

Chin. Phys. B, 2023, 32 (11): 117801. DOI: 10.1088/1674-1056/ace425

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Electronic properties of two-dimensional (2D) materials can be strongly modulated by localized strain. The typical spatial resolution of conventional Kelvin probe force microscopy (KPFM) is usually limited in a few hundreds of nanometers, and it is difficult to characterize localized electronic properties of 2D materials at nanoscales. Herein, tip-enhanced Raman spectroscopy (TERS) is proposed to combine with KPFM to break this restriction. TERS scan is conducted on ReS₂ bubbles deposited on a rough Au thin film to obtain strain distribution by using the Raman peak shift. The localized contact potential difference (CPD) is inversely calculated with a higher spatial resolution by using strain measured by TERS and CPD-strain working curve obtained using conventional KPFM and atomic force microscopy. This method enhances the spatial resolution of CPD measurements and can be potentially used to characterize localized electronic properties of 2D materials.

W-doped In₂O₃ nanofiber optoelectronic neuromorphic transistors with synergistic synaptic plasticity Suggested by editors

Yang Yang(杨洋), Chuanyu Fu(傅传玉), Shuo Ke(柯硕), Hangyuan Cui(崔航源), Xiao Fang(方晓), Changjin Wan(万昌锦), and Qing Wan(万青)

Chin. Phys. B, 2023, 32 (11): 118101. DOI: 10.1088/1674-1056/acdeda

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Neuromorphic devices that mimic the information processing function of biological synapses and neurons have attracted considerable attention due to their potential applications in brain-like perception and computing. In this paper, neuromorphic transistors with W-doped In₂O₃ nanofibers as the channel layers are fabricated and optoelectronic synergistic synaptic plasticity is also investigated. Such nanofiber transistors can be used to emulate some biological synaptic functions, including excitatory postsynaptic current (EPSC), long-term potentiation (LTP), and depression (LTD). Moreover, the synaptic plasticity of the nanofiber transistor can be synergistically modulated by light pulse and electrical pulse. At last, pulsed light learning and pulsed electrical forgetting behaviors were emulated in 5× 5 nanofiber device array. Our results provide new insights into the development of nanofiber optoelectronic neuromorphic devices with synergistic synaptic plasticity.

Effects of oxygen/nitrogen co-incorporation on regulation of growth and properties of boron-doped diamond films Suggested by editors

Dong-Yang Liu(刘东阳), Kun Tang(汤琨), Shun-Ming Zhu(朱顺明), Rong Zhang(张荣), You-Dou Zheng(郑有炓), and Shu-Lin Gu(顾书林)

Chin. Phys. B, 2023, 32 (11): 118102. DOI: 10.1088/1674-1056/ace4b7

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Regulation with nitrogen and oxygen co-doping on growth and properties of boron doped diamond films is studied by using laughing gas as dopant. As the concentration of laughing gas (N₂O/C) increases from 0 to 10%, the growth rate of diamond film decreases gradually, and the nitrogen-vacancy (NV) center luminescence intensity increases first and then weakens. The results show that oxygen in laughing gas has a strong inhibitory effect on formation of NV centers, and the inhibitory effect would be stronger as the concentration of laughing gas increases. As a result, the film growth rate and nitrogen-related compensation donor decrease, beneficial to increase the acceptor concentration (～3.2× 10¹⁹ cm^{-3) in the film. Moreover, it is found that the optimal regulation with the quality and electrical properties of boron doped diamond films could be realized by adding appropriate laughing gas, especially the hole mobility (～700 cm²/V}·s), which is beneficial to the realization of high-quality boron doped diamond films and high-level optoelectronic device applications in the future.

Parameter calculation and result storage for phase-field simulation in α-Mg dendrite growth of Mg-5-wt% Zn alloy

Wei-Peng Chen(陈伟鹏), Hua Hou(侯华), Yun-Tao Zhang(张云涛), Wei Liu(柳伟), and Yu-Hong Zhao(赵宇宏)

Chin. Phys. B, 2023, 32 (11): 118103. DOI: 10.1088/1674-1056/acd7e3

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Parameter calculation and result storage, as two necessary steps in phase-field simulation play an important role in ensuring the accuracy of simulation results. A strategy of parameter calculation and result storage is presented for phase-field simulation in α-Mg dendrite growth of Mg-5-wt% Zn alloy under isothermal solidification. Based on the phase diagram and empirical formulas, key parameters of the phase-field model, such as equilibrium partition coefficient k, liquidus slope m, solutal diffusion coefficient in liquid D_l, and solutal diffusion coefficient in solid D_s, can be obtained. Both structured grid method and structured point method can be used to store simulation results, but using the latter method will reduce about 60% storage space and 37.5% storage time compared with the former. Finally, convergent simulation results of α-Mg dendrite growth are obtained and they are in good agreement with the experimental results about optical micrograph, which verify the accuracy of parameters and stability of storage method.

Increasing linear flux range of SQUID amplifier using self-feedback effect Suggested by editors

Ying-Yu Chen(陈滢宇), Chao-Qun Wang(王超群), Yuan-Xing Xu(徐元星), Yue Zhao(赵越), Li-Liang Ying(应利良), Hang-Xing Xie(谢颃星), Bo Gao(高波), and Zhen Wang(王镇)

Chin. Phys. B, 2023, 32 (11): 118501. DOI: 10.1088/1674-1056/acd8ac

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Superconducting quantum interference devices (SQUIDs) are low-noise amplifiers that are essential for the readouts of translation edge sensors (TESs). The linear flux range is an important parameter for SQUID amplifiers, especially those controlled by high-bandwidth digital flux-locked-loop circuits. A large linear flux range conduces to accurately measuring the input signal and also increasing the multiplexing factor in the time-division multiplexed (TDM) readout scheme of the TES array. In this work, we report that the linear flux range of an SQUID can be improved by using self-feedback effect. When the SQUID loop is designed to be asymmetric, a voltage-biased SQUID shows an asymmetric current-flux (I-Φ) response curve. The linear flux range is improved along the I-Φ curve with a shallow slope. The experimental results accord well with the numerical simulations. The asymmetric SQUID will be able to serve as a building block in the development of the TDM readout systems for large TES arrays.

SiC trench MOSFET with dual shield gate and optimized JFET layer for improved dynamic performance and safe operating area capability

Jin-Ping Zhang(张金平), Wei Chen(陈伟), Zi-Xun Chen(陈子珣), and Bo Zhang(张波)

Chin. Phys. B, 2023, 32 (11): 118502. DOI: 10.1088/1674-1056/acdc8d

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A novel silicon carbide (SiC) trench metal-oxide-semiconductor field-effect transistor (MOSFET) with a dual shield gate (DSG) and optimized junction field-effect transistor (JFET) layer (ODSG-TMOS) is proposed. The combination of the DSG and optimized JFET layer not only significantly improves the device's dynamic performance but also greatly enhances the safe operating area (SOA). Numerical analysis is carried out with Silvaco TCAD to study the performance of the proposed structure. Simulation results show that comparing with the conventional asymmetric trench MOSFET (Con-ATMOS), the specific on-resistance (R_{on, sp}) is significantly reduced at almost the same avalanche breakdown voltage (BV_av). Moreover, the DSG structure brings about much smaller reverse transfer capacitance (C_rss) and input capacitance (C_iss), which helps to reduce the gate-drain charge (Q_gd) and gate charge (Q_g). Therefore, the high frequency figure of merit (HFFOM) of R_{on, sp}· Q_gd and R_{on, sp}· Q_g for the proposed ODSG-TMOS are improved by 83.5% and 76.4%, respectively. The switching power loss of the proposed ODSG-TMOS is 77.0% lower than that of the Con-ATMOS. In addition, the SOA of the proposed device is also enhanced. The saturation drain current (I_d,sat) at a gate voltage (V_gs) of 15 V for the ODSG-TMOS is reduced by 17.2% owing to the JFET effect provided by the lower shield gate (SG) at a large drain voltage. With the reduced I_d,sat, the short-circuit withstand time is improved by 87.5% compared with the Con-ATMOS. The large-current turn-off capability is also improved, which is important for the widely used inductive load applications.

Effect of chaperone-client interaction strength on Hsp70-mediated protein folding

Lujun Zou(邹禄军), Jiajun Lu(陆伽俊), and Xiulian Xu(徐秀莲)

Chin. Phys. B, 2023, 32 (11): 118701. DOI: 10.1088/1674-1056/acea6f

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Protein folding in crowding cellular environment often relies on the assistance of various chaperones. Hsp70 is one of the most ubiquitous chaperones in cells. Previous studies showed that the chaperone-client interactions at the open state tend to remodel the protein folding energy landscape and direct the protein folding as a foldase. In this work, we further investigate how the chaperone-client interaction strength modulates the foldase function of Hsp70 by using molecular simulations. The results showed that the time of substrate folding (including the whole folding step and substrate release step) has a non-monotonic dependence on the interaction strength. With the increasing of the chaperone-client interaction strength, the folding time decreases first, and then increases. More detailed analysis showed that when the chaperone-client interaction is too strong, even small number of chaperones-client contacts can maintain the substrate bound with the chaperone. The sampling of the transient chaperones-client complex with sparse inter-molecule contacts makes the client protein have chance to access the misfolded state even it is bound with chaperone. The current results suggest that the interaction strength is an important factor controlling the Hsp70 chaperoning function.

Effect of short-term plasticity on working memory

Fan Yang(杨帆) and Feng Liu(刘锋)

Chin. Phys. B, 2023, 32 (11): 118706. DOI: 10.1088/1674-1056/acf03a

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The way in which persistent firing activity and synaptic plasticity are orchestrated to underlie working memory in recurrent neural networks is not fully understood. Here, we build a continuous attractor network of pyramidal cells and interneurons to simulate an oculomotor delayed response task. Both short-term facilitation (STF) and short-term depression (STD) manifest at synapses between pyramidal cells. The efficacy of individual synapses depends on the time constants of STF and STD as well as the presynaptic firing rate. Self-sustained firing activity (i.e., a bump attractor) during the delay period encodes the cue position. The bump attractor becomes more robust against random drifts and distractions with enhancing STF or reducing STD. Keeping STF and STD at appropriate levels is crucial for optimizing network performance. Our results suggest that, besides slow recurrent excitation and strong global inhibition, short-term plasticity plays a prominent role in facilitating mnemonic behavior.

Assessing edge-coupled interdependent network disintegration via rank aggregation and elite enumeration

Yong-Hui Li(李咏徽), San-Yang Liu(刘三阳), and Yi-Guang Bai(白艺光)

Chin. Phys. B, 2023, 32 (11): 118901. DOI: 10.1088/1674-1056/ace682

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The disintegration of networks is a widely researched topic with significant applications in fields such as counter-terrorism and infectious disease control. While the traditional approaches for achieving network disintegration involve identifying critical sets of nodes or edges, limited research has been carried out on edge-based disintegration strategies. We propose a novel algorithm, i.e., a rank aggregation elite enumeration algorithm based on edge-coupled networks (RAEEC), which aims to implement tiling for edge-coupled networks by finding important sets of edges in the network while balancing effectiveness and efficiency. Our algorithm is based on a two-layer edge-coupled network model with one-to-one links, and utilizes three advanced edge importance metrics to rank the edges separately. A comprehensive ranking of edges is obtained using a rank aggregation approach proposed in this study. The top few edges from the ranking set obtained by RAEEC are then used to generate an enumeration set, which is continuously iteratively updated to identify the set of elite attack edges. We conduct extensive experiments on synthetic networks to evaluate the performance of our proposed method, and the results indicate that RAEEC achieves a satisfactory balance between efficiency and effectiveness. Our approach represents a significant contribution to the field of network disintegration, particularly for edge-based strategies.

SLGC: Identifying influential nodes in complex networks from the perspectives of self-centrality, local centrality, and global centrality

Da Ai(艾达), Xin-Long Liu(刘鑫龙), Wen-Zhe Kang(康文哲), Lin-Na Li(李琳娜), Shao-Qing Lü(吕少卿), and Ying Liu(刘颖)

Chin. Phys. B, 2023, 32 (11): 118902. DOI: 10.1088/1674-1056/aceee8

Abstract ( 184 )

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Identifying influential nodes in complex networks and ranking their importance plays an important role in many fields such as public opinion analysis, marketing, epidemic prevention and control. To solve the issue of the existing node centrality measure only considering the specific statistical feature of a single dimension, a SLGC model is proposed that combines a node's self-influence, its local neighborhood influence, and global influence to identify influential nodes in the network. The exponential function of e is introduced to measure the node's self-influence; in the local neighborhood, the node's one-hop neighboring nodes and two-hop neighboring nodes are considered, while the information entropy is introduced to measure the node's local influence; the topological position of the node in the network and the shortest path between nodes are considered to measure the node's global influence. To demonstrate the effectiveness of the proposed model, extensive comparison experiments are conducted with eight existing node centrality measures on six real network data sets using node differentiation ability experiments, susceptible-infected-recovered (SIR) model and network efficiency as evaluation criteria. The experimental results show that the method can identify influential nodes in complex networks more accurately.

Thermodynamics of warm axionic Abelian gauge inflation

Xi-Bin Li(李喜彬) and Yan-Ling Wu(武燕玲)

Chin. Phys. B, 2023, 32 (11): 119801. DOI: 10.1088/1674-1056/acea6a

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Inflationary spectral index from the Langevin equation is calculated under the frame of warm inflationary scenario with inflaton interacting with U(1) gauge fields through the Chern-Simons coupling $\propto\phi F_{\mu\nu}\tilde{F}^{\mu\nu}/f$. Under the strong dissipative condition, the spectral index is calculated in terms of the ratio of Hubble parameter to temperature H/T. Then relation between H/T and other cosmic parameters is analytically expressed, based on which a spectral index related to the Chern-Simons coupling strength is further obtained. Numerical results show that cosmic temperature T closes to a constant during inflation and decreases after inflation without a reheating process. Meanwhile, the ratio H/T tends to a constant if the gauged coupling constant is less than a threshold. This phenomenon shows that cosmic temperature may be an important physical parameter with a special value and adiabatic approximation still holds. We obtain the estimate H/T≤0.3377 during inflation from Planck data and other constraint conditions.

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