Table of contents

    16 March 2021, Volume 30 Issue 4 Previous issue    Next issue
    Furi-Martelli-Vignoli spectrum and Feng spectrum of nonlinear block operator matrices
    Xiao-Mei Dong(董小梅), De-Yu Wu(吴德玉), and Alatancang Chen(陈阿拉坦仓)
    Chin. Phys. B, 2021, 30 (4):  040201.  DOI: 10.1088/1674-1056/abd7df
    Abstract ( 222 )   HTML ( 0 )   PDF (510KB) ( 95 )  
    We investigate the Furi-Martelli-Vignoli spectrum and the Feng spectrum of continuous nonlinear block operator matrices, and mainly describe the relationship between the Furi-Martelli-Vignoli spectrum (compared to the Feng spectrum) of the whole operator matrix and that of its entries. In addition, the connection between the Furi-Martelli-Vignoli spectrum of the whole operator matrix and that of its Schur complement is presented by means of Schur decomposition.
    Restricted Boltzmann machine: Recent advances and mean-field theory
    Aurélien Decelle, Cyril Furtlehner
    Chin. Phys. B, 2021, 30 (4):  040202.  DOI: 10.1088/1674-1056/abd160
    Abstract ( 436 )   HTML ( 18 )   PDF (4380KB) ( 301 )  

    This review deals with restricted Boltzmann machine (RBM) under the light of statistical physics. The RBM is a classical family of machine learning (ML) models which played a central role in the development of deep learning. Viewing it as a spin glass model and exhibiting various links with other models of statistical physics, we gather recent results dealing with mean-field theory in this context. First the functioning of the RBM can be analyzed via the phase diagrams obtained for various statistical ensembles of RBM, leading in particular to identify a compositional phase where a small number of features or modes are combined to form complex patterns. Then we discuss recent works either able to devise mean-field based learning algorithms; either able to reproduce generic aspects of the learning process from some ensemble dynamics equations or/and from linear stability arguments.

    Discrete wavelet structure and discrete energy of classical plane light waves
    Xing-Chu Zhang(张兴初) and Wei-Long She(佘卫龙)
    Chin. Phys. B, 2021, 30 (4):  040301.  DOI: 10.1088/1674-1056/abcf34
    Abstract ( 199 )   HTML ( 2 )   PDF (938KB) ( 42 )  
    We find by the wavelet transform that the classical plane light wave of linear polarization can be decomposed into a series of discrete Morlet wavelets. In the theoretical frame, the energy of the classical light wave becomes discrete; interestingly, the discretization is consistent with the energy division of P portions in Planck radiation theory, where P is an integer. It is shown that the changeable energy of a basic plane light wave packet or wave train is $H_0k =np_0k \omega (n=1, 2, 3, \ldots; k=\vert  k\vert$), with discrete wavelet structure parameter n, wave vector k and idler frequency ω , and a constant p0k. The wave-particle duality from the Mach-Zehnder interference of single photons is simulated by using random basic plane light wave packets.
    Pulse-gated mode of commercial superconducting nanowire single photon detectors
    Fan Liu(刘帆), Mu-Sheng Jiang(江木生), Yi-Fei Lu(陆宜飞), Yang Wang(汪洋), and Wan-Su Bao(鲍皖苏)
    Chin. Phys. B, 2021, 30 (4):  040302.  DOI: 10.1088/1674-1056/abc2c2
    Abstract ( 245 )   HTML ( 0 )   PDF (765KB) ( 41 )  
    High detection efficiency and low intrinsic dark count rate are two advantages of superconducting nanowire single photon detectors (SNSPDs). However, the stray photons penetrated into the fiber would cause the extrinsic dark count rate, owing to the free running mode of SNSPDs. In order to improve the performance of SNSPDs in realistic scenarios, stray photons should be investigated and suppression methods should be adopted. In this study, we demonstrate the pulse-gated mode, with 500 kHz gating frequency, of a commercial SNSPD system for suppressing the response of stray photons about three orders of magnitude than its free-running counterpart on the extreme test conditions. When we push the gating frequency to 8 MHz, the dark count rate still keeps under 4% of free-running mode. In experiments, the intrinsic dark count rate is also suppressed to 4.56× 10-2 counts per second with system detection efficiency of 76.4372%. Furthermore, the time-correlated single-photon counting analysis also approves the validity of our mode in suppressing the responses of stray photons.
    SPECIAL TOPIC—Quantum computation and quantum simulation
    Realization of arbitrary two-qubit quantum gates based on chiral Majorana fermions
    Qing Yan(闫青) and Qing-Feng Sun(孙庆丰)
    Chin. Phys. B, 2021, 30 (4):  040303.  DOI: 10.1088/1674-1056/abe296
    Abstract ( 316 )   HTML ( 3 )   PDF (815KB) ( 171 )  
    Quantum computers are in hot-spot with the potential to handle more complex problems than classical computers can. Realizing the quantum computation requires the universal quantum gate set {T, H, CNOT} so as to perform any unitary transformation with arbitrary accuracy. Here we first briefly review the Majorana fermions and then propose the realization of arbitrary two-qubit quantum gates based on chiral Majorana fermions. Elementary cells consist of a quantum anomalous Hall insulator surrounded by a topological superconductor with electric gates and quantum-dot structures, which enable the braiding operation and the partial exchange operation. After defining a qubit by four chiral Majorana fermions, the single-qubit T and H quantum gates are realized via one partial exchange operation and three braiding operations, respectively. The entangled CNOT quantum gate is performed by braiding six chiral Majorana fermions. Besides, we design a powerful device with which arbitrary two-qubit quantum gates can be realized and take the quantum Fourier transform as an example to show that several quantum operations can be performed with this space-limited device. Thus, our proposal could inspire further utilization of mobile chiral Majorana edge states for faster quantum computation.
    Taking tomographic measurements for photonic qubits 88 ns before they are created
    Zhibo Hou(侯志博), Qi Yin(殷琪), Chao Zhang(张超), Han-Sen Zhong(钟翰森), Guo-Yong Xiang(项国勇), Chuan-Feng Li(李传锋), Guang-Can Guo(郭光灿), Geoff J. Pryde, and Anthony Laing
    Chin. Phys. B, 2021, 30 (4):  040304.  DOI: 10.1088/1674-1056/abe29c
    Abstract ( 216 )   HTML ( 1 )   PDF (1101KB) ( 73 )  
    We experimentally demonstrate that tomographic measurements can be performed for states of qubits before they are prepared. A variant of the quantum teleportation protocol is used as a channel between two instants in time, allowing measurements for polarization states of photons to be implemented 88 ns before they are created. Measurement data taken at the early time and later unscrambled according to the results of the protocol's Bell measurements, produces density matrices with an average fidelity of 0.900.01 against the ideal states of photons created at the later time. Process tomography of the time reverse quantum channel finds an average process fidelity of 0.840.02. While our proof-of-principle implementation necessitates some post-selection, the general protocol is deterministic and requires no post-selection to sift desired states and reject a larger ensemble.
    Efficient self-testing system for quantum computations based on permutations
    Shuquan Ma(马树泉), Changhua Zhu(朱畅华), Min Nie(聂敏), and Dongxiao Quan(权东晓)
    Chin. Phys. B, 2021, 30 (4):  040305.  DOI: 10.1088/1674-1056/abe29a
    Abstract ( 271 )   HTML ( 1 )   PDF (590KB) ( 111 )  
    Verification in quantum computations is crucial since quantum systems are extremely vulnerable to the environment. However, verifying directly the output of a quantum computation is difficult since we know that efficiently simulating a large-scale quantum computation on a classical computer is usually thought to be impossible. To overcome this difficulty, we propose a self-testing system for quantum computations, which can be used to verify if a quantum computation is performed correctly by itself. Our basic idea is using some extra ancilla qubits to test the output of the computation. We design two kinds of permutation circuits into the original quantum circuit: one is applied on the ancilla qubits whose output indicates the testing information, the other is applied on all qubits (including ancilla qubits) which is aiming to uniformly permute the positions of all qubits. We show that both permutation circuits are easy to achieve. By this way, we prove that any quantum computation has an efficient self-testing system. In the end, we also discuss the relation between our self-testing system and interactive proof systems, and show that the two systems are equivalent if the verifier is allowed to have some quantum capacity.
    Quantum annealing for semi-supervised learning
    Yu-Lin Zheng(郑玉鳞), Wen Zhang(张文), Cheng Zhou(周诚), and Wei Geng(耿巍)
    Chin. Phys. B, 2021, 30 (4):  040306.  DOI: 10.1088/1674-1056/abe298
    Abstract ( 209 )   HTML ( 0 )   PDF (1032KB) ( 83 )  
    Recent advances in quantum technology have led to the development and the manufacturing of programmable quantum annealers that promise to solve certain combinatorial optimization problems faster than their classical counterparts. Semi-supervised learning is a machine learning technique that makes use of both labeled and unlabeled data for training, which enables a good classifier with only a small amount of labeled data. In this paper, we propose and theoretically analyze a graph-based semi-supervised learning method with the aid of the quantum annealing technique, which efficiently utilizes the quantum resources while maintaining good accuracy. We illustrate two classification examples, suggesting the feasibility of this method even with a small portion (30%) of labeled data involved.
    Electron transfer properties of double quantum dot system in a fluctuating environment
    Lujing Jiang(姜露静), Kang Lan(蓝康), Zhenyu Lin(林振宇), and Yanhui Zhang(张延惠)
    Chin. Phys. B, 2021, 30 (4):  040307.  DOI: 10.1088/1674-1056/abd759
    Abstract ( 201 )   HTML ( 0 )   PDF (866KB) ( 48 )  
    Using the innovative method of the additional Bloch vector, the electron transfer properties of a double quantum dot (DQD) system measured by a quantum point contact (QPC) in a fluctuating environment are investigated. The results show that the environmental noises in transverse and longitudinal directions play different roles in the dynamical evolution of the open quantum systems. Considering the DQD with symmetric energy level, the Fano factor exhibits a slight peak with the increase of transverse noise amplitude σ T, which provides a basis for distinguishing dynamical phenomena caused by different directional fluctuation noises in symmetric DQD structures by studying the detector output. In the case of asymmetric DQD, the dependence of a detector current involving the level displacement is distinct when increasing the transverse noise damping coefficient τ T and the longitudinal noise damping coefficient τε respectively. Meanwhile, the transverse noise damping coefficient τT could significantly reduce the Fano factor and enhance the stability of the quantum system compared with the longitudinal one. The Fano factors with stable values as the enhancement of noise amplitudes show different external influences from the detector measurement, and provide a numerical reference for adjusting the noise amplitudes in both transverse and longitudinal directions appropriately in a microscopic experimental process to offset the decoherence effect caused by the measurements. Finally, the research of average waiting time provides unique insights to the development of single electron transfer theory in the short-time limit.
    Equilibrium dynamics of the sub-ohmic spin-boson model at finite temperature
    Ke Yang(杨珂) and Ning-Hua Tong(同宁华)
    Chin. Phys. B, 2021, 30 (4):  040501.  DOI: 10.1088/1674-1056/abd393
    Abstract ( 208 )   HTML ( 0 )   PDF (996KB) ( 33 )  
    We use the full-density matrix numerical renormalization group method to calculate the equilibrium dynamical correlation function C(ω) of the spin operator σz at finite temperature for the sub-ohmic spin-boson model. A peak is observed at the frequency ωTT in the curve of C(ω). The curve merges with the zero-temperature C(ω) in $\omega \gg \omega_\rm T$ and deviates significantly from the zero-temperature curve in ω «ω T.
    Effects of notch structures on DC and RF performances of AlGaN/GaN high electron mobility transistors
    Hao Zou(邹浩), Lin-An Yang(杨林安), Xiao-Hua Ma(马晓华), and Yue Hao(郝跃)
    Chin. Phys. B, 2021, 30 (4):  040502.  DOI: 10.1088/1674-1056/abd470
    Abstract ( 309 )   HTML ( 0 )   PDF (3285KB) ( 84 )  
    The effects of various notch structures on direct current (DC) and radio frequency (RF) performances of AlGaN/GaN high electron mobility transistors (HEMTs) are analyzed. The AlGaN/GaN HEMTs, each with a 0.8-μm gate length, 50-μm gate width, and 3-μm source-drain distance in various notch structures at the AlGaN/GaN barrier layer, are manufactured to achieve the desired DC and RF characteristics. The maximum drain current (I ds,max), pinch-off voltage (V th), maximum transconductance (g m), gate voltage swing (GVS), subthreshold current, gate leakage current, pulsed I-V characteristics, breakdown voltage, cut-off frequency (f T), and maximum oscillation frequency (fmax) are investigated. The results show that the double-notch structure HEMT has a 30% improvement of gate voltage swing, a 42.2% improvement of breakdown voltage, and a 9% improvement of cut-off frequency compared with the conventional HEMT. The notch structure also has a good suppression of the current collapse.
    General M-lumps, T-breathers, and hybrid solutions to (2+1)-dimensional generalized KDKK equation
    Peisen Yuan(袁培森), Jiaxin Qi(齐家馨), Ziliang Li(李子良), and Hongli An(安红利)
    Chin. Phys. B, 2021, 30 (4):  040503.  DOI: 10.1088/1674-1056/abcf9f
    Abstract ( 316 )   HTML ( 0 )   PDF (4478KB) ( 131 )  
    A special transformation is introduced and thereby leads to the N-soliton solution of the (2+1)-dimensional generalized Konopelchenko-Dubrovsky-Kaup-Kupershmidt (KDKK) equation. Then, by employing the long wave limit and imposing complex conjugate constraints to the related solitons, various localized interaction solutions are constructed, including the general M-lumps, T-breathers, and hybrid wave solutions. Dynamical behaviors of these solutions are investigated analytically and graphically. The solutions obtained are very helpful in studying the interaction phenomena of nonlinear localized waves. Therefore, we hope these results can provide some theoretical guidance to the experts in oceanography, atmospheric science, and weather forecasting.
    Theoretical analysis and experimental validation of radial cascaded composite ultrasonic transducer
    Xiao-Yu Wang(王晓宇), Zhi-Xin Yu(余芷欣), Jing Hu(胡静), and Shu-Yu Lin(林书玉)
    Chin. Phys. B, 2021, 30 (4):  040701.  DOI: 10.1088/1674-1056/abd399
    Abstract ( 161 )   HTML ( 0 )   PDF (1362KB) ( 27 )  
    A radial cascaded composite ultrasonic transducer is analyzed. The transducer consists of three short metal tubes and two radially polarized piezoelectric ceramic short tubes arranged alternately along the radial direction. The short metal tubes and the piezoelectric ceramic short tubes are connected in parallel electrically and in series mechanically, which can multiply the input sound power and sound intensity. Based on the theory of plane stress, the electro-mechanical equivalent circuit of radial vibration of the transducer is derived firstly. The resonance/anti-resonance frequency equation and the expression of the effective electromechanical coupling coefficient are obtained. Excellent electromechanical characteristics are determined by changing the radial geometric dimensions. Two prototypes of the transducers are designed and manufactured to support the analytical theory. It is concluded that the theoretical resonance/anti-resonance frequencies are consistent with the numerical and experimental results. When R2 is at certain values, both the anti-resonance frequency and effective electromechanical coupling coefficient corresponding to the second mode have maximal values. The radial cascaded composite ultrasonic transducer is expected to be used in the fields of ultrasonic water treatment and underwater acoustics.
    Super-resolution imaging of low-contrast periodic nanoparticle arrays by microsphere-assisted microscopy
    Qin-Fang Shi(石勤芳), Song-Lin Yang(杨松林), Yu-Rong Cao(曹玉蓉), Xiao-Qing Wang(王晓晴), Tao Chen(陈涛), and Yong-Hong Ye(叶永红)
    Chin. Phys. B, 2021, 30 (4):  040702.  DOI: 10.1088/1674-1056/abcf48
    Abstract ( 194 )   HTML ( 0 )   PDF (1629KB) ( 35 )  
    We use the label-free microsphere-assisted microscopy to image low-contrast hexagonally close-packed polystyrene nanoparticle arrays with diameters of 300 and 250 nm. When a nanoparticle array is directly placed on a glass slide, it cannot be distinguished. If a 30-nm-thick Ag film is deposited on the surface of a nanoparticle array, the nanoparticle array with nanoparticle diameters of 300 and 250 nm can be distinguished. In addition, the Talbot effect of the 300-nm-diameter nanoparticle array is also observed. If a nanoparticle sample is assembled on a glass slide deposited with a 30-nm-thick Ag film, an array of 300-nm-diameter nanoparticles can be discerned. We propose that in microsphere-assisted microscopy imaging, the resolution can be improved by the excitation of surface plasmon polaritons (SPPs) on the sample surface or at the sample/substrate interface, and a higher near-field intensity due to the excited SPPs would benefit the resolution improvement. Our study of label-free super-resolution imaging of low-contrast objects will promote the applications of microsphere-assisted microscopy in life sciences.
    Effect of Sm doping into CuInTe2 on cohesive energy before and after light absorption
    Tai Wang(王泰), Yong-Quan Guo(郭永权), and Cong Wang(王聪)
    Chin. Phys. B, 2021, 30 (4):  043101.  DOI: 10.1088/1674-1056/abd167
    Abstract ( 196 )   HTML ( 0 )   PDF (724KB) ( 20 )  
    The effects of Sm doping into CuInTe2 chalcopyrite on the cohesive energy before and after light absorption are systematically investigated by the empirical electron theory (EET) of solids and molecules. The results show that the static energy of CuIn1-xSmxTe2 decreases with Sm content increasing due to the valence electronic structure modulated by doping Sm into CuIn1-xSmxTe2. The calculated optical absorption transition energy from the static state to the excited energy level in CuIn1-xSmxTe2 accords well with the experimental absorption bandgap of CuIn1-xSmxTe2. Moreover, it is found that the energy bandgap of CuIn1-xSmxTe2 is significantly widened with Sm content increasing due to its special valent electron structure, which is favorable for enhancing the light absorption in a wider range and also for the potential applications in solar cells.
    Isotope shift of the 2s 2S1/2 $\rightarrow$ 2p 2P1/2,3/2 transitions of Li-like Ca ions
    Denghong Zhang(张登红), Fangjun Zhang(张芳军), Xiaobin Ding(丁晓彬), and Chenzhong Dong(董晨钟)
    Chin. Phys. B, 2021, 30 (4):  043102.  DOI: 10.1088/1674-1056/abc7a2
    Abstract ( 196 )   HTML ( 0 )   PDF (786KB) ( 37 )  
    The mass-and field-shift parameters of the two 2s 2S1/2 $\rightarrow$ 2p 2P1/2,3/2 transitions in the Li-like Ca ions are calculated by using multi-configuration Dirac-Hartree-Fock (MCDHF) and the relativistic configuration interaction (RCI) methods with the inclusion of the transverse photon (Breit) interaction, vacuum polarization and self-energy corrections. In addition, the mass shift and field shift of these two transitions are calculated, where the field shift is calculated by using the evaluated value $\delta\langle r^2\rangle$ obtained by [Atomic Data and Nuclear Data Tables 9969 (2013)]. It is found that the mass shift of Li-like Ca ions is greater than the field shift.
    Calculations of atomic polarizability for beryllium using MCDHF method
    Hui Dong(董辉), Jun Jiang(蒋军), Zhongwen Wu(武中文), Chenzhong Dong(董晨钟), and Gediminas Gaigalas
    Chin. Phys. B, 2021, 30 (4):  043103.  DOI: 10.1088/1674-1056/abd92d
    Abstract ( 333 )   HTML ( 0 )   PDF (745KB) ( 1576 )  
    Based on the fully relativistic multiconfiguration Dirac-Hartree-Fock (MCDHF) method and the corresponding program package GRASP2018, a new program for calculating the polarizabilities is developed. As the first application, the static electric-dipole polarizabilities of the ground state 2s2 1S0 and excited state 2s2p 3P0 of beryllium are calculated. By means of these polarizabilities, the blackbody radiation (BBR) shift of the 2s2p $^3P_0 \to \rm 2s^2$ 1S0 clock transition is determined. The present results agree very well with other available theoretical results.
    Molecular photoelectron momentum and angular distributions of N2 molecules by ultrashort attosecond laser pulses
    Si-Qi Zhang(张思琪), Qi Zhen(甄琪), Zhi-Jie Yang(杨志杰), Jun Zhang(张军), Ai-Hua Liu(刘爱华), Kai-Jun Yuan(元凯军), Xue-Shen Liu(刘学深), and Jing Guo(郭静)
    Chin. Phys. B, 2021, 30 (4):  043201.  DOI: 10.1088/1674-1056/abca22
    Abstract ( 321 )   HTML ( 0 )   PDF (2020KB) ( 159 )  
    The ultrafast photoionization dynamics of N2 molecules by x-ray/XUV laser pulses is investigated. The molecular frame photoelectron momentum distributions (MF-PMDs) and the molecular frame photoelectron angular distributions (MF-PADs) are obtained by numerically solving 2D time-dependent Schrödinger equations within the single-electron approximation (SEA) frame. The results show that the molecular photoionization diffraction appears in 5 nm laser fields. However, when the laser wavelength is 30 nm, the molecular photoionization diffraction disappears and the MF-PMDs show four-lobe pattern. The ultrafast photoionization model can be employed to describe the MF-PMDs and MF-PADs of N2 molecules.
    Generation of non-integer high-order harmonics and significant enhancement of harmonic intensity
    Chang-Long Xia(夏昌龙), Yue-Yue Lan(兰悦跃), and Xiang-Yang Miao(苗向阳)
    Chin. Phys. B, 2021, 30 (4):  043202.  DOI: 10.1088/1674-1056/abd389
    Abstract ( 197 )   HTML ( 1 )   PDF (1142KB) ( 44 )  
    High-order harmonics from helium atom in the orthogonally two-color (OTC) laser field are investigated by solving the two-dimensional time-dependent Schrödinger equation. Non-integer high-order harmonics are obtained in some ratio of frequencies of two components. Pure odd and even harmonics from atoms could be separated in two components by adjusting the ratio of frequencies in OTC scheme, and the resolution of harmonics is improved at the same time. The physical mechanism is explained by the periodicity of dipole. With the same intensity of the incident laser, the intensity of the high-order harmonics from the OTC field scheme is improved by three orders of magnitude compared to the monochromatic laser field scheme. A theoretical scheme is provided for experimentally achieving improving energy resolution and separation of pure odd and even harmonics in atoms. Also, we provide a means for improving harmonic intensity.
    Raman investigation of hydration structure of iodide and iodate
    Zhe Liu(刘喆), Hong-Liang Zhao(赵洪亮), Hong-Zhi Lang(郎鸿志), Ying Wang(王莹), Zhan-Long Li(李占龙), Zhi-Wei Men(门志伟), Sheng-Han Wang(汪胜晗), and Cheng-Lin Sun(孙成林)
    Chin. Phys. B, 2021, 30 (4):  043301.  DOI: 10.1088/1674-1056/abe2fa
    Abstract ( 226 )   HTML ( 0 )   PDF (1103KB) ( 56 )  
    In the troposphere, the destruction of ozone and the formation of new particles are closely related to the iodine content, which mainly comes from iodide (I-) and iodate (IO3-) in the seawater. Therefore, understanding the interactions between I-, IO3- and water molecules plays a certain role in alleviating the destruction of the ozone layer. Raman spectroscopy is commonly used to obtain the information of the interaction between I-, IO3- and water molecules quickly and accurately. Herein, the effect of I- and IO3- on the change in Raman band characteristics of water is investigated to reflect the associated intermolecular interactions change. With the addition of the two ions, the Raman band corresponding to OH stretching vibration moves towards the high wavenumber, indicating the formation of hydration structure. The narrowing of the Raman band from OH stretching vibration under weak hydrogen bond agrees well with the hydrogen bond variation, while the abnormal broadening of the Raman band from OH stretching vibration under strong hydrogen bond indicates the formation of H-down structure. With the increase of ions concentration, the frequency shift of the Raman band from OH stretching vibration under both weak and strong hydrogen bonds becomes more apparent. Meanwhile, the frequency shift of I- is more obvious than that of IO3-, which indicates that I- is more likely to form the hydration structure with water than IO3-. These results contribute to analyzing the different interactions between I--water and IO3--water, then helping to prevent ozone depletion.
    Local dynamical characteristics of Bessel beams upon reflection near the Brewster angle
    Zhi-Wei Cui(崔志伟), Shen-Yan Guo(郭沈言), Yuan-Fei Hui(惠元飞), Ju Wang(王举), and Yi-Ping Han(韩一平)
    Chin. Phys. B, 2021, 30 (4):  044201.  DOI: 10.1088/1674-1056/abd390
    Abstract ( 197 )   HTML ( 0 )   PDF (3366KB) ( 44 )  
    We analytically and numerically study the local dynamical characteristics of the Bessel beams reflected from an air-glass interface near the Brewster angle. A Taylor series expansion based on the angular spectrum component is applied to correct the reflection coefficients near the Brewster angle. Using a hybrid angular spectrum representation and vector potential method, the explicit expressions for the electric and magnetic field components of the reflected Bessel beams are derived analytically under paraxial approximation. The local energy, momentum, spin, and orbital angular momentum of the Bessel beams upon reflection near the Brewster angle are examined numerically by utilizing a canonical approach. Numerical simulation results show that the properties of these dynamical quantities for the Bessel beams near Brewster angle incidence change abruptly, and are significantly affected by their topological charge, half-cone angle, and polarization state. The present study has its importance in understanding the dynamical aspects of optical beams with vortex structure and diffraction-free nature during the reflection process.
    Incoherent digital holographic spectral imaging with high accuracy of image pixel registration
    Feng-Ying Ma(马凤英), Xi Wang(王茜), Yuan-Zhuang Bu(卜远壮), Yong-Zhi Tian(田勇志), Yanli Du(杜艳丽) , Qiao-Xia Gong(弓巧侠), Ceyun Zhuang(庄策云), Jinhai Li(李金海), and Lei Li(李磊)
    Chin. Phys. B, 2021, 30 (4):  044202.  DOI: 10.1088/1674-1056/abd2aa
    Abstract ( 193 )   HTML ( 0 )   PDF (2367KB) ( 36 )  
    Fresnel incoherent correlation holography (FINCH) is a unique three-dimensional (3D) imaging technique which has the advantages of scanning-free, high resolution, and easy matching with existing mature optical systems. In this article, an incoherent digital holographic spectral imaging method with high accuracy of spectral reconstruction based on liquid crystal tunable filter (LCTF) and FINCH is proposed. Using the programmable characteristics of spatial light modulator (SLM), a series of phase masks, none of whose focal lengths changes with wavelength, is designed and made. For each wavelength of LCTF output, SLM calls three phase masks with different phase constants at the corresponding wavelength, and CCD records three holograms. The spectral images obtained by this method have a constant magnification, which can achieve pixel-level image registration, restrain image registration errors, and improve spectral reconstruction accuracy. The results show that this method can not only obtain the 3D spatial information and spectral information of the object simultaneously, but also have high accuracy of spectral reconstruction and excellent color reproducibility.
    Zebrafish imaging and two-photon fluorescence imaging using ZnSe quantum dots
    Nan-Nan Zhang(张楠楠), Li-Ya Zhou(周立亚), Xiao Liu(刘潇), Zhong-Chao Wei(韦中超), Hai-Ying Liu(刘海英), Sheng Lan(兰胜), Zhao Meng(孟钊), and Hai-Hua Fan(范海华)
    Chin. Phys. B, 2021, 30 (4):  044204.  DOI: 10.1088/1674-1056/abd467
    Abstract ( 242 )   HTML ( 1 )   PDF (1083KB) ( 32 )  
    This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility, which can be used in bioimaging. Fluorescence emission at 410 nm is observed in the quantum dot under 760-nm laser excitation. These biocompatible quantum dots exhibit a two-photon cross-section of 9.1× 105 GM (1 GM=10-50 cm4s/photon). Two-photon excited laser scanning microscopic images show that cells co-cultured with ZnSe quantum dots are found in the blue channel at a fluorescence intensity that is 14.5 times that of control cells not co-cultured with quantum dots. After incubating zebrafish larvae with ZnSe quantum dots for 24 h, the fluorescence intensity of the yolk sac stimulated by ultraviolet light is 2.9 times that of the control group. The proposed material shows a great potential application in biological imaging.
    Dual-function beam splitter of high contrast gratings
    Wen-Jing Fang(房文敬), Xin-Ye Fan(范鑫烨), Hui-Juan Niu(牛慧娟), Xia Zhang (张霞), Heng-Ying Xu(许恒迎), and Cheng-Lin Bai(白成林)
    Chin. Phys. B, 2021, 30 (4):  044205.  DOI: 10.1088/1674-1056/abd68d
    Abstract ( 187 )   HTML ( 1 )   PDF (1994KB) ( 15 )  
    We present the design and fabrication of a novel dual-function high contrast gratings that can be used as a polarization-selective beam splitter with transverse magnetic polarization, which performs two independent functions, i.e., reflection focusing and power equalization at a wavelength of 1550 nm. This dual-function grating profile is optimized by the rigorous coupled-wave analysis and the finite-element method. Simple analytical expressions of phase and modal guideline for the beam splitter design are given. The beam splitter based on the grating structure is experimentally studied at a distance of 160 μ m from the reflection plane, the results are consistent with the theoretical results basically.
    A scanning distortion correction method based on X- Y galvanometer Lidar system
    Bao-Ling Qi(漆保凌), Chun-Hui Wang(王春晖), Dong-Bing Guo(郭东兵), and Bin Zhang(张斌)
    Chin. Phys. B, 2021, 30 (4):  044206.  DOI: 10.1088/1674-1056/abcf42
    Abstract ( 274 )   HTML ( 0 )   PDF (2619KB) ( 33 )  
    \baselineskip=12pt plus.2pt minus.2pt Aiming at the problem of scanning distortion in X-Y galvanometer light detecting and ranging (Lidar) scanning system, we propose a method of image scanning distortion correction with controllable driving voltage compensation. Firstly, the geometrical optics vectors model is established to explain the principle of pincushion distortion in the galvanometer scanning system, and the simulation result of scanning trajectory is consistent with experiments. The linear relationship between the driving voltage and the scanning angle of the galvanometer is verified. Secondly, the relationship between the deflection angle of the galvanometer and the scanning trajectory and the driving voltage is deduced respectively, and an image scanning correction algorithm with controllable driving voltage compensation is obtained. The simulation experiment results of the proposed method show that the root-mean-square error (RMSE) and the corresponding curve between the scan value and the actual value at different distances, have a good correction effect for the pincushion distortion. Finally, the X-Y galvanometer scanning Lidar system is established to obtain undistorted two-dimensional scanned image and it can be applied to the three-dimensional Lidar scanning system in the actual experiments, which further demonstrates the feasibility and practicability of our method.
    Three-dimensional spatial multi-point uniform light focusing through scattering media based on feedback wavefront shaping
    Fan Yang(杨帆), Yang Zhao(赵杨), Chengchao Xiang(向成超), Qi Feng(冯祺), and Yingchun Ding(丁迎春)
    Chin. Phys. B, 2021, 30 (4):  044207.  DOI: 10.1088/1674-1056/abe3e6
    Abstract ( 211 )   HTML ( 0 )   PDF (1767KB) ( 88 )  
    We use feedback wavefront shaping technology to realize the multi-point uniform light focusing in three-dimensional (3D) space through scattering media only by loading the optimal mask once. General 3D spatial focusing needs to load the optimal mask multiple times to realize the spatial movement of the focal point and the uniformity of multi-point focusing cannot be guaranteed. First, we investigate the effects of speckle axial correlation and different axial distances on 3D spatial multi-point uniform focusing and propose possible solutions. Then we use our developed non-dominated sorting genetic algorithm suitable for 3D spatial focusing (S-NSGA) to verify the experiment of multi-point focusing in 3D space. This research is expected to have potential applications in the fields of optical manipulation and optogenetics.
    Sensitivity enhancement of micro-optical gyro with photonic crystal
    Liu Yang(杨柳), Shuhua Zhao(赵舒华), Jingtong Geng(耿靖童), Bing Xue(薛冰), and Yonggang Zhang(张勇刚)
    Chin. Phys. B, 2021, 30 (4):  044208.  DOI: 10.1088/1674-1056/abe3f3
    Abstract ( 242 )   HTML ( 2 )   PDF (1269KB) ( 156 )  
    We propose a core rotation-sensing element for improving the sensitivity of the micro-optical gyroscope using the large nonreciprocal effect with a photonic crystal. The sharp transmission peak of electromagnetically induced transparency in photonic crystal generated from a periodic distribution of cold atoms is sensitive to the rotation. Our numerical results show that the sensitivity of relative rotation is about 50 times higher and the sensitivity of absolute rotation is more than two orders higher than that of the traditional resonant optical gyroscope. Also, the sensitivity of the gyroscope can be manipulated by varying the atomic density, modulation frequency, probe pulse width, and photonic crystal length, etc.
    Generation of wideband tunable femtosecond laser based on nonlinear propagation of power-scaled mode-locked femtosecond laser pulses in photonic crystal fiber Hot!
    Zhiguo Lv(吕志国) and Hao Teng(滕浩)
    Chin. Phys. B, 2021, 30 (4):  044209.  DOI: 10.1088/1674-1056/abe231
    Abstract ( 422 )   HTML ( 0 )   PDF (1089KB) ( 239 )  
    We implement an experimental study for the generation of wideband tunable femtosecond laser with a home-made power-scaled mode-locked fiber oscillator as the pump source. By coupling the sub-100 fs mode-locked pulses into a nonlinear photonic crystal fiber (NL-PCF), the exited spectra have significant nonlinear broadening and cover a spectra range of hundreds of nm. In experiment, by reasonably optimizing the structure parameters of NL-PCF and regulating the power of the incident pulses, femtosecond laser with tuning range of 900-1290 nm is realized. The research approach promotes the development of femtosecond lasers with center wavelengths out of the traditional laser gain media toward the direction of simplicity and ease of implementation.
    Analysis of relative wavelength response characterization and its effects on scanned-WMS gas sensing
    Dao Zheng(郑道), Zhi-Min Peng(彭志敏), Yan-Jun Ding(丁艳军), and Yan-Jun Du(杜艳君)
    Chin. Phys. B, 2021, 30 (4):  044210.  DOI: 10.1088/1674-1056/abdb1c
    Abstract ( 191 )   HTML ( 0 )   PDF (4814KB) ( 89 )  
    Our recently proposed three-step method showed the promising potential to improve the accuracy of relative wavelength response (RWR) characterization in the wavelength-modulation spectroscopy (WMS) over the commonly used summation method. A detailed comparison of the three-step method and the summation method, for the wavelength-scanned WMS gas-sensing, was performed with different laser parameters (modulation indexes and scan indexes) and gas properties (pressures and concentrations). Simulation results show that the accuracy of the predicted gas parameters is strongly limited by the RWR characterization with large modulation index and high gas pressure conditions. Both fitting residuals of RWR and errors of predicted gas parameters from the recently proposed three-step method are nearly 2 orders of magnitude smaller than those from the summation method. In addition, the three-step method is further improved by introducing a coupling term for the 2 nd harmonic amplitude. Experiments with CO2 absorption transition at 6976.2026 cm -1 were conducted and validated the simulation analysis. The modified-three-step method presents an improved accuracy in RWR description with at least 5% smaller fitting residual for all conditions compared with the three-step method, although the deviation of the deduced CO2 concentrations between these two methods does not exceed 0.2%.
    High-efficiency terahertz wave generation with multiple frequencies by optimized cascaded difference frequency generation
    Zhongyang Li(李忠洋), Binzhe Jiao(焦彬哲), Wenkai Liu(刘文锴), Qingfeng Hu(胡青峰), Gege Zhang(张格格), Qianze Yan(颜钤泽), Pibin Bing(邴丕彬), Fengrui Zhang(张风蕊), Zhan Wang(王湛), and Jianquan Yao(姚建铨)
    Chin. Phys. B, 2021, 30 (4):  044211.  DOI: 10.1088/1674-1056/abe3eb
    Abstract ( 305 )   HTML ( 4 )   PDF (4345KB) ( 84 )  
    High-efficiency terahertz (THz) wave generation with multiple frequencies by optimized cascaded difference frequency generation (OCDFG) is investigated at 100 K using a nonlinear crystal consisting of a periodically poled lithium niobate (PPLN) part and an aperiodically poled lithium niobate (APPLN) part. Two infrared pump waves with a frequency difference ω T1 generate THz waves and a series of cascaded optical waves in the PPLN part by cascaded difference frequency generation (CDFG). The generated cascaded optical waves with frequency interval ω T1 then further interact in the APPLN part by OCDFG, yielding the following two advantages. First, OCDFG in the APPLN part is efficiently stimulated by inputting multi-order cascaded optical waves rather than the only two intense infrared pump waves, yielding unprecedented energy conversion efficiencies in excess of 37% at 1 THz at 100 K. Second, THz waves with M times ω T1 are generated by mixing the mth-order and the (m+M)th-order cascaded optical waves by designing poling period distributions of the APPLN part.
    SPECIAL TOPIC—Quantum computation and quantum simulation
    Realization of adiabatic and diabatic CZ gates in superconducting qubits coupled with a tunable coupler
    Huikai Xu(徐晖凯), Weiyang Liu(刘伟洋), Zhiyuan Li(李志远), Jiaxiu Han(韩佳秀), Jingning Zhang(张静宁), Kehuan Linghu(令狐克寰), Yongchao Li(李永超), Mo Chen(陈墨), Zhen Yang(杨真), Junhua Wang(王骏华), Teng Ma(马腾), Guangming Xue(薛光明), Yirong Jin(金贻荣), and Haifeng Yu(于海峰)
    Chin. Phys. B, 2021, 30 (4):  044212.  DOI: 10.1088/1674-1056/abf03a
    Abstract ( 438 )   HTML ( 0 )   PDF (1576KB) ( 152 )  
    High fidelity two-qubit gates are fundamental for scaling up the superconducting qubit number. We use two qubits coupled via a frequency-tunable coupler which can adjust the coupling strength, and demonstrate the CZ gate using two different schemes, adiabatic and diabatic methods. The Clifford based randomized benchmarking (RB) method is used to assess and optimize the CZ gate fidelity. The fidelities of adiabatic and diabatic CZ gates are 99.53(8)% and 98.72(2)%, respectively. We also analyze the errors induced by the decoherence. Comparing to 30 ns duration time of adiabatic CZ gate, the duration time of diabatic CZ gate is 19 ns, revealing lower incoherence error rate $r'_{incoherent, int} = 0.0197(5)$ compared to $r_{incoherent, int} = 0.0223(3)$.
    SPECIAL TOPIC—Optical field manipulation
    Quantum plasmon enhanced nonlinear wave mixing in graphene nanoflakes
    Hanying Deng(邓寒英), Changming Huang(黄长明), Yingji He(何影记), and Fangwei Ye(叶芳伟)
    Chin. Phys. B, 2021, 30 (4):  044213.  DOI: 10.1088/1674-1056/abea8d
    Abstract ( 225 )   HTML ( 2 )   PDF (1753KB) ( 66 )  
    A distant-neighbor quantum-mechanical method is used to study the nonlinear optical wave mixing in graphene nanoflakes (GNFs), including sum-and difference-frequency generation, as well as four-wave mixing. Our analysis shows that molecular-scale GNFs support quantum plasmons in the visible spectrum region, and significant enhancement of nonlinear optical wave mixing is achieved. Specifically, the second-and third-order wave-mixing polarizabilities of GNFs are dramatically enhanced, provided that one (or more) of the input or output frequencies coincide with a quantum plasmon resonance. Moreover, by embedding a cavity into hexagonal GNFs, we show that one can break the structural inversion symmetry and enable otherwise forbidden second-order wave mixing, which is found to be enhanced by the quantum plasmon resonance too. This study reveals that the molecular-sized graphene could be used in the quantum regime for nanoscale nonlinear optical devices and ultrasensitive molecular sensors.
    SPECIAL TOPIC—Quantum computation and quantum simulation
    Speeding up generation of photon Fock state in a superconducting circuit via counterdiabatic driving
    Xin-Ping Dong(董新平), Xiao-Jing Lu(路晓静), Ming Li(李明), Zheng-Yin Zhao(赵正印), and Zhi-Bo Feng(冯志波)
    Chin. Phys. B, 2021, 30 (4):  044214.  DOI: 10.1088/1674-1056/abe297
    Abstract ( 261 )   HTML ( 0 )   PDF (709KB) ( 97 )  
    Optimal creation of photon Fock states is of importance for quantum information processing and state engineering. Here an efficient strategy is presented for speeding up generation of photon Fock state in a superconducting circuit via counterdiabatic driving. A transmon qubit is dispersively coupled to a quantized electrical field. We address a $\Lambda $ -configuration interaction between the composite system and classical drivings. Based on two Gaussian-shaped drivings, a single-photon Fock state can be generated adiabatically. Instead of adding an auxiliary counterdiabatic driving, our concern is to modify these two Rabi drivings in the framework of shortcut to adiabaticity. Thus an accelerated operation with high efficiency can be realized in a much shorter time. Compared with the adiabatic counterpart, the shortcut-based operation is significantly insusceptible to decoherence effects. The scheme could offer a promising way to deterministically prepare photon Fock states with superconducting quantum circuits.
    Influence of the coupled-dipoles on photosynthetic performance in a photosynthetic quantum heat engine
    Ling-Fang Li(李玲芳) and Shun-Cai Zhao(赵顺才)
    Chin. Phys. B, 2021, 30 (4):  044215.  DOI: 10.1088/1674-1056/abdea6
    Abstract ( 190 )   HTML ( 0 )   PDF (708KB) ( 33 )  
    Recent evidence suggests that the multiple charge-separation pathways can contribute to photosynthetic performance. In this work, the influence of coupled-dipoles on photosynthetic performance was investigated in a two-charge separation pathways quantum heat engine (QHE) model. And the population dynamics of the two coupled sites, j-V characteristics, and power involving this photosynthetic QHE model were evaluated for the photosynthetic performance. The results illustrate that the photosynthetic performance can be greatly enhanced but quantum interference is deactivated by the coupled-dipoles between the two-charge separation pathways. However, the photosynthetic performance can also be promoted by the deactivated quantum interference owing to the coupled-dipoles. It is a novel role of the coupled-dipoles in the energy transport process of biological photosynthetic, and some artificial strategies may be motivated by this photosynthetic QHE model in the future.
    Axial acoustic radiation force on an elastic spherical shell near an impedance boundary for zero-order quasi-Bessel-Gauss beam
    Yu-Chen Zang(臧雨宸), Wei-Jun Lin(林伟军), Chang Su(苏畅), and Peng-Fei Wu(吴鹏飞)
    Chin. Phys. B, 2021, 30 (4):  044301.  DOI: 10.1088/1674-1056/abca27
    Abstract ( 228 )   HTML ( 1 )   PDF (1475KB) ( 35 )  
    Shell structures have increasingly widespread applications in biomedical ultrasound fields such as contrast agents and drug delivery, which requires the precise prediction of the acoustic radiation force under various circumstances to improve the system efficiency. The acoustic radiation force exerted by a zero-order quasi-Bessel-Gauss beam on an elastic spherical shell near an impedance boundary is theoretically and numerically studied in this study. By means of the finite series method and the image theory, a zero-order quasi-Bessel-Gauss beam is expanded in terms of spherical harmonic functions, and the exact solution of the acoustic radiation force is derived based on the acoustic scattering theory. The acoustic radiation force function, which represents the radiation force per unit energy density and per unit cross-sectional surface, is especially investigated. Some simulated results for a polymethyl methacrylate shell and an aluminum shell are provided to illustrate the behavior of acoustic radiation force in this case. The simulated results show the oscillatory property and the negative radiation force caused by the impedance boundary. An appropriate relative thickness of the shell can generate sharp peaks for a polymethyl methacrylate shell. Strong radiation force can be obtained at small half-cone angles and the beam waist only affects the results at high frequencies. Considering that the quasi-Bessel-Gauss beam possesses both the energy focusing property and the non-diffracting advantage, this study is expected to be useful in the development of acoustic tweezers, contrast agent micro-shells, and drug delivery applications.
    Weak-focused acoustic vortex generated by a focused ring array of planar transducers and its application in large-scale rotational object manipulation
    Yuzhi Li(李禹志), Peixia Li(李培霞), Ning Ding(丁宁), Gepu Guo(郭各朴), Qingyu Ma(马青玉), Juan Tu(屠娟), and Dong Zhang(章东)
    Chin. Phys. B, 2021, 30 (4):  044302.  DOI: 10.1088/1674-1056/abca1f
    Abstract ( 259 )   HTML ( 0 )   PDF (3396KB) ( 70 )  
    Contactless manipulation of multi-scale objects using the acoustic vortex (AV) tweezers offers tremendous perspectives in biomedical applications. However, it is still hindered by the weak acoustic radiation force (ARF) and torque (ART) around the vortex center. By introducing the elevation angle to the planar transducers of an N-element ring array, the weak-focused acoustic vortex (WFAV) composed of a main-AV and N paraxial-AVs is constructed to conduct a large-scale object manipulation. Different from the traditional focused AV (FAV) generated by a ring array of concave spherical transducers, a much larger focal region of the WFAV is generated by the main lobes of the planar transducers with the size inversely associated with the elevation angle. With the pressure simulation of the acoustic field, the capability of the rotational object driving in the focal plane for the WFAV is analyzed using the ARF and the ART exerted on an elastic ball based on acoustic scattering. With the experimental system built in water, the generation of the WFAV is verified by the scanning measurements of the acoustic field and the capability of object manipulation is also analyzed by the rotational trapping of floating particles in the focal plane. The favorable results demonstrate the feasibility of large-scale rotational manipulation of objects with a strengthened ART and a reduced acousto-thermal damage to biological tissues, showing a promising prospect for potential applications in clinical practice.
    Instability of single-walled carbon nanotubes conveying Jeffrey fluid
    Bei-Nan Jia(贾北楠) and Yong-Jun Jian(菅永军)
    Chin. Phys. B, 2021, 30 (4):  044601.  DOI: 10.1088/1674-1056/abcf36
    Abstract ( 144 )   HTML ( 0 )   PDF (1345KB) ( 25 )  
    We report instability of the single-walled carbon nanotubes (SWCNT) filled with non-Newtonian Jeffrey fluid. Our objective is to get the influences of relaxation time and retardation time of the Jeffrey fluid on the vibration frequency and the decaying rate of the amplitude of carbon nanotubes. An elastic Euler-Bernoulli beam model is used to describe vibrations and structural instability of the carbon nanotubes. A new vibration equation of an SWCNT conveying Jeffrey fluid is first derived by employing Euler-Bernoulli beam equation and Cauchy momentum equation taking constitutive relation of Jeffrey fluid into account. The complex vibrating frequencies of the SWCNT are computed by solving a cubic eigenvalue problem based upon differential quadrature method (DQM). It is interesting to find from computational results that retardation time has significant influences on the vibration frequency and the decaying rate of the amplitude. Especially, the vibration frequency decreases and critical velocity increases with the retardation time. That is to say, longer retardation time makes the SWCNT more stable.
    Investigation of cavitation bubble collapse in hydrophobic concave using the pseudopotential multi-relaxation-time lattice Boltzmann method
    Minglei Shan(单鸣雷), Yu Yang(杨雨), Xuemeng Zhao(赵雪梦), Qingbang Han(韩庆邦), and Cheng Yao(姚澄)
    Chin. Phys. B, 2021, 30 (4):  044701.  DOI: 10.1088/1674-1056/abcf4b
    Abstract ( 333 )   HTML ( 1 )   PDF (1371KB) ( 46 )  
    The interaction between cavitation bubble and solid surface is a fundamental topic which is deeply concerned for the utilization or avoidance of cavitation effect. The complexity of this topic is that the cavitation bubble collapse includes many extreme physical phenomena and variability of different solid surface properties. In the present work, the cavitation bubble collapse in hydrophobic concave is studied using the pseudopotential multi-relaxation-time lattice Boltzmann model (MRT-LB). The model is modified by involving the piecewise linear equation of state and improved forcing scheme. The fluid-solid interaction in the model is employed to adjust the wettability of solid surface. Moreover, the validity of the model is verified by comparison with experimental results and grid-independence verification. Finally, the cavitation bubble collapse in a hydrophobic concave is studied by investigating density field, pressure field, collapse time, and jet velocity. The superimposed effect of the surface hydrophobicity and concave geometry is analyzed and explained in the framework of the pseudopotential LBM. The study shows that the hydrophobic concave can enhance cavitation effect by decreasing cavitation threshold, accelerating collapse and increasing jet velocity.
    A simplified approximate analytical model for Rayleigh-Taylor instability in elastic-plastic solid and viscous fluid with thicknesses
    Xi Wang(王曦), Xiao-Mian Hu(胡晓棉), Sheng-Tao Wang(王升涛), and Hao Pan(潘昊)
    Chin. Phys. B, 2021, 30 (4):  044702.  DOI: 10.1088/1674-1056/abcf44
    Abstract ( 175 )   HTML ( 0 )   PDF (760KB) ( 31 )  
    A simplified theoretical model for the linear Rayleigh-Taylor instability of finite thickness elastic-plastic solid constantly accelerated by finite thickness viscous fluid is performed. With the irrotational assumption, it is possible to consider viscosity, surface tension, elasticity or plasticity effects simultaneously. The model considers thicknesses at rigid wall boundary conditions with the velocity potentials, and deals with solid elastic-plastic transition and fluid viscosity based on the velocity continuity and force equilibrium at contact interface. The complete analytical expressions of the amplitude motion equation, the growth rate, and the instability boundary are obtained for arbitrary Atwood number, viscosity, thicknesses of solid and fluid. The thicknesses effects of two materials on the growth rate and the instability boundary are discussed.
    Continuous droplet rebound on heated surfaces and its effects on heat transfer property: A lattice Boltzmann study
    Qing-Yu Zhang(张庆宇), Qi-Peng Dong(董其鹏), Shan-Lin Wang(王山林), Zhi-Jun Wang(王志军), and Jian Zhou(周健)
    Chin. Phys. B, 2021, 30 (4):  044703.  DOI: 10.1088/1674-1056/abd745
    Abstract ( 286 )   HTML ( 0 )   PDF (1962KB) ( 195 )  
    A thermal multiphase lattice Boltzmann (LB) model is used to study the behavior of droplet impact on hot surface and the relevant heat transfer properties. After validating the correctness of the codes through the D2 law, the simulations of intrinsic contact angle and the temperature-dependent surface tension are performed. The LB model is then used to simulate the droplet impact on smooth and micro-hole heated surface. On the smooth surface, the impinging droplet is reluctant to rebound, unless the intrinsic wettability of the solid surface is fairly good. On the micro-hole surface, however, the micro-holes provide favorable sites for generating a high-pressure vapor cushion underneath the impinging droplet, which thereby facilitates the continuous droplet rebound. For the continuously rebounding droplet. The time evolution of volume and temperature display obvious oscillations. The achievable height of the rebounding droplet increases as the intrinsic wettability of the solid surface becomes better, and the maximum transient heat flux is found to be directly proportional to the droplet rebounding height. Within a certain time interval, the continuous rebounding behavior of the droplet is favorable for enhancing the total heat quantity/heat transfer efficiency, and the influence of intrinsic wettability on the total heat during droplet impingement is greater than that of the superheat. The LB simulations not only present different states of droplets on hot surfaces, but also guide the design of the micro-hole surface with desirable heat transfer properties.
    Decomposition reaction of phosphate rock under the action of microwave plasma
    Hui Zheng(郑慧), Meng Yang(杨猛), Cheng-Fa Jiang(江成发), and Dai-Jun Liu(刘代俊)
    Chin. Phys. B, 2021, 30 (4):  045201.  DOI: 10.1088/1674-1056/abccb6
    Abstract ( 176 )   HTML ( 0 )   PDF (985KB) ( 22 )  
    The decomposition reaction of phosphate rock under the action of microwave plasma was investigated. Phosphate rock and its decomposition products were characterized by x-ray diffraction (XRD), energy disperse spectroscopy (EDS), and chemical analysis. The measurements of electron temperature (T e) and electron density (N e) of plasma plume under atmospheric pressure were carried out using optical emission spectroscopy(OES). The electron temperature (T e) was determined based on the calculation of the relative intensity of the O II (301.91 nm) and O II (347.49 nm) spectral lines. Correspondingly, electron densities were obtained using the Saha ionization equation which was based on the C I (247.86 nm) line and the C II (296.62 nm) line under the assumption of local thermodynamic equilibrium (LTE). The relationship between the relative intensity of the active components and the gas output was studied by the spectrometer. Finally the reaction mechanism of the decomposition of the phosphate rock under the action of the atmospheric pressure microwave plasma was proposed. The results showed that with the increase of CO flow and microwave power, the electron temperature and electron density in the plasma show a decreasing and increasing trend. The CO is dissociated into gaseous carbon ions under the action of microwave plasma, and the presence of gaseous carbon ions promotes the decomposition of the phosphate rock.
    Spatio-temporal measurements of overshoot phenomenon in pulsed inductively coupled discharge
    Xiang-Yun Lv(吕翔云), Fei Gao(高飞), Quan-Zhi Zhang(张权治), and You-Nian Wang(王友年)
    Chin. Phys. B, 2021, 30 (4):  045202.  DOI: 10.1088/1674-1056/abd16b
    Abstract ( 250 )   HTML ( 0 )   PDF (1387KB) ( 212 )  
    Pulse inductively coupled plasma has been widely used in the microelectronics industry, but the existence of overshoot phenomenon may affect the uniformity of plasma and generate high-energy ions, which could damage the chip. The overshoot phenomenon at various spatial locations in pulsed inductively coupled Ar and Ar/CF4 discharges is studied in this work. The electron density, effective electron temperature, relative light intensity, and electron energy probability function (EEPF) are measured by using a time-resolved Langmuir probe and an optical probe, as a function of axial and radial locations. At the initial stage of pulse, both electron density and relative light intensity exhibit overshoot phenomenon, i.e., they first increase to a peak value and then decrease to a convergent value. The overshoot phenomenon gradually decays, when the probe moves away from the coils. Meanwhile, a delay appears in the variation of the electron densities, and the effective electron temperature decreases, which may be related to the reduced strength of electric field at a distance, and the consequent fewer high-energy electrons, inducing limited ionization and excitation rate. The overshoot phenomenon gradually disappears and the electron density decreases, when the probe moves away from reactor centre. In Ar/CF4 discharge, the overshoot phenomenon of electron density is weaker than that in the Ar discharge, and the plasma reaches a steady density within a much shorter time, which is probably due to the more ionization channels and lower ionization thresholds in the Ar/CF4 plasma.
    Attenuation characteristics of obliquely incident electromagnetic wave in weakly ionized dusty plasma based on modified Bhatnagar-Gross-Krook collision model
    Zhaoying Wang(王召迎), Lixin Guo(郭立新), and Jiangting Li(李江挺)
    Chin. Phys. B, 2021, 30 (4):  045203.  DOI: 10.1088/1674-1056/abe230
    Abstract ( 195 )   HTML ( 0 )   PDF (676KB) ( 94 )  
    The attenuation characteristics of obliquely incident electromagnetic (EM) wave in L-Ka frequency band in weakly ionized dusty plasma are analyzed based on the modified Bhatnagar-Gross-Krook (BGK) collision model. According to the kinetic equation and the charging theory, the total complex dielectric constant of the weakly ionized dusty plasma is derived by considering that the minimum velocity of the electron accessible to the dust particle surface is non-zero and the second potential part of the collision cross-section contributes to the charging. The attenuation characteristics within the modified model are compared with those within the traditional model. The influence of the dusty plasma parameters and the incident angle of EM waves on the attenuation in weakly ionized dusty plasma is further analyzed. Finally, the influence of different reentry heights on the attenuation characteristics of the obliquely incident EM wave is discussed. The results show that the effect of the minimum electron velocity and the second term of the collision cross-section on the attenuation characteristics of EM waves cannot be ignored. When the dust density and dust radius are changed, the trends of the attenuation of obliquely incident EM waves are consistent, but the influence of dust density is weaker than that of dust radius due to the constraint of orbit-limited motion (OLM) theory. The plasma thickness, electron density, and incident angle are proportional to the attenuation amplitude of EM waves. The effect of different reentry heights on the attenuation obliquely incident EM waves is related to the electron density and plasma thickness.
    Ground-state structure and physical properties of YB 3 predicted from first-principles calculations
    Bin-Hua Chu(初斌华), Yuan Zhao(赵元), and De-Hua Wang(王德华)
    Chin. Phys. B, 2021, 30 (4):  046101.  DOI: 10.1088/1674-1056/abcf94
    Abstract ( 145 )   HTML ( 0 )   PDF (1223KB) ( 12 )  
    Using the calypso algorithm with first-principles calculations, we have predicted two orthorhombic Cmmm and Pmmm structures for YB3. The new structures are energetically much better than the previously proposed WB3-type, ReB3-type, FeB3-type, and TcP3-type structures. We find that the Cmmm phase transforms to the Pmmm phase at about 31 GPa. Subsequent calculations show that the Cmmm phase is mechanical and dynamical stable at ambient conditions. The analysis of the chemical bonding properties indicates that there are strong B-B bonds that make considerable contributions to its stability.
    X-ray absorption investigation of the site occupancies of the copper element in nominal Cu3Zn(OH)6FBr Hot!
    Ruitang Wang(王瑞塘), Xiaoting Li(李效亭), Xin Han(韩鑫), Jiaqi Lin(林佳琪), Yong Wang(王勇), Tian Qian(钱天), Hong Ding(丁洪), Youguo Shi(石友国), and Xuerong Liu(柳学榕)
    Chin. Phys. B, 2021, 30 (4):  046102.  DOI: 10.1088/1674-1056/abe0c8
    Abstract ( 268 )   HTML ( 0 )   PDF (913KB) ( 126 )  
    With Zn substitution to the three-dimensional antiferromagnetically ordered barlowite Cu4(OH)6FBr, Cu3Zn(OH)6FBr shows no magnetic phase transition down to 50 mK, and the system is suggested to be a two-dimensional kagomé quantum spin liquid [Chin. Phys. Lett. 34 077502 (2017)]. A key issue to identify such phase diagram is the exact chemical formula of the substituted compound. With Cu L-edge x-ray absorption spectrum (XAS) combined with the MultiX XAS calculations, we evaluate the Cu concentration in a nominal Cu3Zn(OH)6FBr sample. Our results show that although the Cu concentration is 2.80, close to the expected value, there is 34% residual Cu occupation in intersite layers between kagomé layers. Thus the Zn substitution of the intersite layers is not complete, and likely it intrudes the kagomé layers.
    Effect of strain on electrochemical performance of Janus MoSSe monolayer anode material for Li-ion batteries: First-principles study
    Guoqing Wang(王国庆), Wenjing Qin(秦文静), and Jing Shi(石晶)
    Chin. Phys. B, 2021, 30 (4):  046301.  DOI: 10.1088/1674-1056/abca24
    Abstract ( 191 )   HTML ( 2 )   PDF (1242KB) ( 25 )  
    First-principles calculations are performed to investigate the effect of strain on the electrochemical performance of Janus MoSSe monolayer. The calculation focuses on the specific capacity, intercalation potential, electronic structure, and migration behavior of Li-ion under various strains by using the climbing-image nudged elastic band method. The result shows that the specific capacity is nearly unchanged under strain. But interestingly, the tensile strain can cause the intercalation potential and Li-ion migration energy barrier increase in MoSSe monolayer, whereas the compressive strain can lead to the intercalation potential and energy barrier decreasing. Thus, the rate performance of the MoSSe anode is improved. By analyzing the potential energy surface of MoSSe surface and equilibrium adsorption distance of Li-ion, we explain the physical origin of the change in the intercalation potential and migration energy barrier. The increase of MoSSe potential energy surface and the decrease of adsorption distance caused by tensile strain are the main reason that hinders Li-ion migration.
    Two-dimensional MnN utilized as high-capacity anode for Li-ion batteries Hot!
    Junping Hu(胡军平), Zhangyin Wang(王章寅), Genrui Zhang(张根瑞), Yu Liu(刘宇), Ning Liu(刘宁), Wei Li(李未), Jianwen Li(李健文), Chuying Ouyang(欧阳楚英), and Shengyuan A. Yang(杨声远)
    Chin. Phys. B, 2021, 30 (4):  046302.  DOI: 10.1088/1674-1056/abdda8
    Abstract ( 392 )   HTML ( 0 )   PDF (1351KB) ( 246 )  
    When developing high performance lithium-ion batteries, high capacity is one of the key indicators. In the last decade, the progress of two-dimensional (2D) materials has provided new opportunities for boosting the storage capacity. Here, based on first-principles calculation method, we predict that MnN monolayer, a recently proposed 2D nodal-loop half-metal containing the metallic element Mn, can be used as a super high-capacity lithium-ion batteries anode. Its theoretical capacity is above 1554 mAh/g, more than four times that of graphite. Meanwhile, it also satisfies other requirements for a good anode material. Specifically, we demonstrate that MnN is mechanically, dynamically, and thermodynamically stable. The configurations before and after lithium adsorption exhibit good electrical conductivity. The study of Li diffusion on its surface reveals a very low diffusion barrier (∼ 0.12 eV), indicating excellent rate performance. The calculated average open-circuit voltage of the corresponding half-cell at full charge is also very low (∼ 0.22 V), which facilitates higher operating voltage. In addition, the lattice changes of the material during lithium intercalation are very small (∼ 1.2%-∼ 4.8%), which implies good cycling performance. These results suggest that 2D MnN can be a very promising anode material for lithium-ion batteries.
    A comparative study of the self-propelled jumping capabilities of coalesced droplets on RTV surfaces and superhydrophobic surfaces
    Sheng-Wu Wang(王晟伍), Lu Peng(彭璐), Jun-Wu Chen(陈俊武), and Lee Li(李黎)
    Chin. Phys. B, 2021, 30 (4):  046501.  DOI: 10.1088/1674-1056/abeedb
    Abstract ( 212 )   HTML ( 0 )   PDF (1051KB) ( 52 )  
    Understanding the mechanism of coalescence-induced self-propelled jumping behavior provides distinct insights in designing and optimizing functional coatings with self-cleaning and anti-icing properties. However, to date self-propelled jumping phenomenon has only been observed and studied on superhydrophobic surfaces, other than those hydrophobic surfaces with weaker but fairish water-repellency, for instance, vulcanized silicon rubber (RTV) coatings. In this work, from the perspective of thermodynamic-based energy balance aspect, the reason that self-propelled jumping phenomenon does not happen on RTV coatings is studied. The apparent contact angles of droplets on RTV coatings can be less than the theoretical critical values therefore cannot promise energy surplus for the coalesced droplets onside. Besides, on RTV and superhydrophobic surfaces, the droplet-size dependent variation characteristics of the energy leftover from the coalescence process are opposite. For the droplets coalescing on RTV coatings, the magnitudes of energy dissipations are more sensitive to the increase in droplet size, compared to that of released surface energy. While for superhydrophobic coatings, the energy generated during the coalescence process can be more sensitive than the dissipations to the change in droplet size.
    Quantum nature of proton transferring across one-dimensional potential fields Hot!
    Cheng Bi(毕成), Quan Chen (陈泉), Wei Li(李伟), and Yong Yang(杨勇)
    Chin. Phys. B, 2021, 30 (4):  046601.  DOI: 10.1088/1674-1056/abe114
    Abstract ( 292 )   HTML ( 0 )   PDF (1514KB) ( 195 )  
    Proton transfer plays a key role in the applications of advanced energy materials as well as in the functionalities of biological systems. In this work, based on the transfer matrix method, we study the quantum effects of proton transfer in a series of one-dimensional (1D) model potentials and numerically calculate the quantum probability of transferring across single and double barriers (wells). In the case of single barriers, when the incident energies of protons are above the barrier height, the quantum oscillations in the transmission coefficients depend on the geometric shape of the barriers. It is found that atomic resonant tunneling (ART) not only presents in the rectangular single well and rectangular double barriers as expected, but also exists in the other types of potential wells and double barriers. For hetero-structured double barriers, there is no resonant tunneling in the classical forbidden zone, i.e., in the case when the incident energy (E i) is lower than the barrier height (E b). Furthermore, we have provided generalized analysis on the characteristics of transmission coefficients of hetero-structured rectangular double barriers.
    Super-strong interactions between multivalent anions and graphene
    Xing Liu(刘星) and Guosheng Shi(石国升)
    Chin. Phys. B, 2021, 30 (4):  046801.  DOI: 10.1088/1674-1056/abd396
    Abstract ( 187 )   HTML ( 1 )   PDF (1427KB) ( 79 )  
    Based on the density functional theory (DFT) calculations, we showed that the interactions between different valence anions (PO43-, CH3PO42-, (CH3)2PO4-) and graphene significantly increased as the valence of anion increased from negative monovalence to negative trivalence. The adsorption energy of (CH3)2PO4- on the electron-rich graphene flake (C84H24) is -8.3 kcal/mol. The adsorption energy of CH3PO42- on the electron-rich graphene flake (C84H24) is -48.0 kcal/mol, which is about six times that of (CH3)2PO4- adsorption on electron-rich graphene flake (C84H24) and is even much larger than that of CO32- adsorption on electron-deficient aromatic ring C6F6 (-28.4 kcal/mol). The adsorption energy of PO43- on the electron-rich graphene flake (C84H24) is -159.2 kcal/mol, which is about 20 times that of (CH3)2PO4- adsorption on the graphene flake (C84H24). The super-strong adsorption energy is mainly attributed to the orbital interactions between multivalent anions and graphene. This work provides new insights for understanding the interaction between multivalent anions and π -electron-rich carbon-based nanomaterials and is helpful for the design of graphene-based DNA biosensor.
    First principles study of behavior of helium at Fe(110)-graphene interface
    Yan-Mei Jing(荆艳梅) and Shao-Song Huang(黄绍松)
    Chin. Phys. B, 2021, 30 (4):  046802.  DOI: 10.1088/1674-1056/abd46d
    Abstract ( 193 )   HTML ( 0 )   PDF (1010KB) ( 22 )  
    Recently, metal-graphene nanocomposite system has aroused much interest due to its radiation tolerance behavior. However, the related atomic mechanism for the metal-graphene interface is still unknown. Further, stainless steels with Fe as main matrix are widely used in nuclear systems. Therefore, in this study, the atomic behaviors of point defects and helium (He) atoms at the Fe(110)-graphene interface are investigated systematically by first principles calculations. The results indicate that graphene interacts strongly with the Fe(110) substrate. In comparison with those of the original graphene and bulk Fe, the formation energy values of C vacancies and Fe point defects decrease significantly for Fe(110)-graphene. However, as He atoms have a high migration barrier and large binding energy at the interface, they are trapped at the interface once they enter into it. These theoretical results suggest that the Fe(110)-graphene interface acts as a strong sink that traps defects, suggesting the potential usage of steel-graphene with multiply interface structures for tolerating the radiation damage.
    Passivation of PEA+ to MAPbI3 (110) surface states by first-principles calculations
    Wei Hu(胡伟), Ying Tian(田颖), Hong-Tao Xue(薛红涛), Wen-Sheng Li(李文生), and Fu-Ling Tang(汤富领)
    Chin. Phys. B, 2021, 30 (4):  047101.  DOI: 10.1088/1674-1056/abccb7
    Abstract ( 144 )   HTML ( 0 )   PDF (910KB) ( 9 )  
    The MAPbI3 (110) surface with low indices of crystal face is a stable and highly compatible photosensitive surface. Since the electronic states on the surface can be detrimental to the photovoltaic efficiency of the device, they should be passivated. Phenylethylamine (PEA+), as a molecular ligand, has been widely used in continuous degradation and interfacial charge recombination experiments, and has satisfactory performance in improving surface defects. Therefore, we construct an adsorption model of MAPbI3 with small molecules, calculating the lattice structure and electronic properties of PEA+-adsorbed MAPbI3 (110) surface. It is found that PEA+ as a passivator can effectively weaken the electronic states and regulate the band gap of the MAPbI3 (110) surface. Before and after adding the passivator, the peak value of electronic state densities at MAPbI3 (110) surface is reduced by about 50%, and the band gap is apparently reduced. Moreover, by comparing the Bader atomic charge and spatial charge distributions before and after PEA+'s adsorption on the surface of MAPbI3, we observe a substantial change of PEA+ charges, which suggests the surface states have been passivated by PEA+.
    Polarization-resolved Raman spectra of α -PtO2
    Zhanhong Lei(雷展宏), Weiliang Wang(王伟良), and Juncong She(佘峻聪)
    Chin. Phys. B, 2021, 30 (4):  047102.  DOI: 10.1088/1674-1056/abccb5
    Abstract ( 141 )   HTML ( 0 )   PDF (1258KB) ( 20 )  
    Using density functional theory, we investigate the vibrational properties and polarization-resolved Raman spectra of α -PtO2 and obtain the Raman tensor and angle-dependent Raman intensity of α -PtO2. It is found that the polar plot of A 1g mode in parallel polarization configuration is useful in identifying the orientation of the crystal. The Raman intensity of the Eg mode is about five times stronger than that of the A1g mode. The Raman intensity is about three times stronger when the wave vector of the incident light is in x or y direction than in z direction. Our work will help the material scientists to characterize the α -PtO2 and to identify its orientation by comparing the experimental spectra with our result.
    Analysis on degradation mechanisms of normally-off p-GaN gate AlGaN/GaN high-electron mobility transistor
    Si-De Song(宋思德), Su-Zhen Wu(吴素贞), Guo-Zhu Liu(刘国柱), Wei Zhao(赵伟), Yin-Quan Wang(王印权), Jian-Wei Wu(吴建伟), and Qi He(贺琪)
    Chin. Phys. B, 2021, 30 (4):  047103.  DOI: 10.1088/1674-1056/abccba
    Abstract ( 155 )   HTML ( 0 )   PDF (2118KB) ( 32 )  
    The degradation mechanisms of enhancement-mode p-GaN gate AlGaN/GaN high-electron mobility transistor was analyzed extensively, by means of drain voltage stress and gate bias stress. The results indicate that: (i) High constant drain voltage stress has only a negligible impact on the device electrical parameters, with a slightly first increase and then decrease in output current; (ii) A negative shift of threshold voltage and increased output current were observed in the device subjected to forward gate bias stress, which is mainly ascribed to the hole-trapping induced by high electric field across the p-GaN/AlGaN interface; (iii) The analyzed device showed an excellent behavior at reverse gate bias stress, with almost unaltered threshold voltage, output current, and gate leakage current, exhibiting a large gate swing in the negative direction. The results are meaningful and valuable in directing the process optimization towards a high voltage and high reliable enhanced AlGaN/GaN high-electron mobility transistor.
    First-principles calculations of F-, Cl-, and N-related defects of amorphous SiO 2 and their impacts on carrier trapping and proton release
    Xin Gao(高鑫), Yunliang Yue(乐云亮), Yang Liu(刘杨), and Xu Zuo(左旭)
    Chin. Phys. B, 2021, 30 (4):  047104.  DOI: 10.1088/1674-1056/abe3f7
    Abstract ( 167 )   HTML ( 0 )   PDF (1400KB) ( 53 )  
    The first-principles calculations based on density functional theory are performed to study F-, Cl-, and N-related defects of amorphous SiO2 (a-SiO2) and their impacts on carrier trapping and proton release. The possible geometric configurations of the impurity-related defects, the formation energies, the hole or electron trapping of the neutral defects, and the mechanisms to suppress proton diffusion by doping N are investigated. It is demonstrated by the calculations that the impurity atoms can interact with the oxygen vacancies and result in impurity-related defects. The reactions can be utilized to saturate oxygen vacancies that will cause ionization damage to the semiconducting devices. Moreover, the calculated formation energy indicates that the F-or Cl-related oxygen vacancy defect is a deep hole trap, which can trap holes and prevent them from diffusing to the a-SiO2/Si interface. However, three N-related defects, namely N(2)o-H, N(2)o=O, and N(3)o-V o, tend to act as shallow hole traps to facilitate hole transportation during device operation. The N(2)o and N(3)o configurations can be negatively charged as deep electron traps during the oxide charge buildup after ionization radiation. In addition, the nudged elastic band (NEB) calculations show that four N-related defects, namely N(2)o, N(2)o-H, N(2)o=O, and N(3)o are capable of capturing protons and preventing them from diffusing to and de-passivating the interface. This research reveals the fundamental properties of the F-, Cl-, and N-related defects in amorphous silica and the details of the reactions of the carrier trapping and proton release. The findings help to understand the microscopic mechanisms that alleviate ionization damage of semiconducting devices by doping a-SiO2.
    Ultra-low Young's modulus and high super-exchange interactions in monolayer CrN: A promising candidate for flexible spintronic applications
    Yang Song(宋洋), Yan-Fang Zhang(张艳芳), Jinbo Pan(潘金波), and Shixuan Du(杜世萱)
    Chin. Phys. B, 2021, 30 (4):  047105.  DOI: 10.1088/1674-1056/abdb20
    Abstract ( 174 )   HTML ( 0 )   PDF (1283KB) ( 72 )  
    Monolayer CrN has been predicted to be half-metallic ferromagnet with high Curie temperature. Due to bulk CrN's biocompatibility, the monolayer is a promising candidate for bio-related devices. Here, using first-principles calculations based on density functional theory, we find that the formation energy of the bulk CrN stacking from layers with square lattice is only 68 meV/atom above the convex hull, suggesting a great potential to fabricate the monolayer CrN in a square lattice by using molecular beam epitaxy method. The monolayer CrN is then proved to be a soft material with an ultra-low Young's modulus and can sustain very large strains. Moreover, the analysis of the projected density of states demonstrates that the ferromagnetic half-metallicity originates from the splitting of Cr-d orbitals in the CrN square crystal field, the bonding interaction between Cr-N, and that between Cr-Cr atoms. It is worth noting that the super-exchange interaction is much larger than the direct-exchange interaction and contributes to the ultra-high Curie temperature, which is obtained from Monte Carlo simulations based on Heisenberg model. Our findings suggest that the monolayer CrN can be an indispensable candidate for nanoscale flexible spintronic applications with good biocompatibility and is considerable appealing to be realized in experiment.
    Resistivity minimum emerges in Anderson impurity model modified with Sachdev-Ye-Kitaev interaction
    Lan Zhang(张欄), Yin Zhong(钟寅), and Hong-Gang Luo(罗洪刚)
    Chin. Phys. B, 2021, 30 (4):  047106.  DOI: 10.1088/1674-1056/abefcb
    Abstract ( 169 )   HTML ( 0 )   PDF (916KB) ( 21 )  
    We investigate a modified Anderson model at the large-N limit, where the Coulomb interaction is replaced by the Sachdev-Ye-Kitaev random interaction. The resistivity of conduction electron ρ c has a minimum value around temperature $T^\star$, which is similar to the Kondo system, but the impurity electron's density of state A d(ω) demonstrates no sharp-peak like the Kondo resonance around the Fermi surface. This provides a counterintuitive example where resistivity minimum exists without Kondo resonance. The impurity electron's entropy S d and specific heat capacity $C_v$ show a crossover from Fermi liquid to a non-Fermi liquid behavior dependent on temperature. The system is a Fermi liquid at $T<T^\star$ and becomes a non-Fermi liquid at $T>T^\star$, and then becomes a Fermi gas at sufficiently high temperatures $T\gg T^\star$. The non-Fermi liquid at the intermediate-T regime does not occur in the standard Anderson model. We also make a renormalization group analysis, which confirms the crossover from Fermi liquid to the non-Fermi behavior. It is emphasized that the resistivity minimum emerges in our model when the system behaves as a non-Fermi liquid rather than Fermi liquid, which provides an alternative example showing resistivity minimum in condensed matter physics.
    Implementation of synaptic learning rules by TaOx memristors embedded with silver nanoparticles
    Yue Ning(宁玥), Yunfeng Lai(赖云锋), Jiandong Wan(万建栋), Shuying Cheng(程树英), Qiao Zheng(郑巧), and Jinling Yu(俞金玲)
    Chin. Phys. B, 2021, 30 (4):  047301.  DOI: 10.1088/1674-1056/abccb8
    Abstract ( 154 )   HTML ( 0 )   PDF (1143KB) ( 20 )  
    As an alternative device for neuromorphic computing to conquer von Neumann bottleneck, the memristor serving as an artificial synapse has attracted much attention. The TaOx memristors embedded with silver nanoparticles (Ag NPs) have been fabricated to implement synaptic plasticity and to investigate the effects of Ag NPs. The TaOx memristors with and without Ag NPs are capable of simulating synaptic plasticity (PTP, STDP, and STP to LTP), learning, and memory behaviors. The conduction of the high resistance state (HRS) is driven by Schottky-emission mechanism. The embedment of Ag NPs causes the low resistance state (LRS) conduction governed by a Poole-Frenkel emission mechanism instead of a space-charge-limited conduction (SCLC) in a pure TaOx system, which is ascribed to the Ag NPs enhancing electric field to produce additional traps and to reduce Coulomb potential energy of bound electrons to assist electron transport. Consequently, the enhanced electric fields induced by Ag NPs increase the learning strength and learning speed of the synapses. Additionally, they also improve synaptic sensitivity to stimuli. The linearity of conductance modulation and the reproducibility of conductance are improved as well.
    Flexible and degradable resistive switching memory fabricated with sodium alginate
    Zhuang-Zhuang Li(李壮壮), Zi-Yang Yan(严梓洋), Jia-Qi Xu(许嘉琪), Xiao-Han Zhang(张晓晗), Jing-Bo Fan(凡井波), Ya Lin(林亚), and Zhong-Qiang Wang(王中强)
    Chin. Phys. B, 2021, 30 (4):  047302.  DOI: 10.1088/1674-1056/abc67a
    Abstract ( 194 )   HTML ( 0 )   PDF (3783KB) ( 21 )  
    Transient electronics has attracted interest as an emerging technology to solve electronic-waste problem, due to its physically vanishing ability in solution. Here in this work, we demonstrate a flexible and degradable transient resistive switching (RS) memory device with simple structure of Cu/sodium alginate (SA)/ITO. The device presents excellent RS characteristics as well as high flexibility, including low operating voltage (<1.5 V) and multilevel RS behavior. No performance degradation occurs after bending the device 50 times. Moreover, our device can be absolutely dissolved in deionized water. The proposed SA-based transient memory device has great potential for the development of green and security memory devices.
    Digital and analog memory devices based on 2D layered MPS3 ( M=Mn, Co, Ni) materials
    Guihua Zhao(赵贵华), Li Wang(王力), Xi Ke(柯曦), and Zhiyi Yu(虞志益)
    Chin. Phys. B, 2021, 30 (4):  047303.  DOI: 10.1088/1674-1056/abd397
    Abstract ( 183 )   HTML ( 0 )   PDF (980KB) ( 37 )  
    We demonstrate digital and analog devices with an Ag/MPS3/Au structure based on layered MPS3 (M=Mn, Co, Ni) 2D materials. All devices show the bipolar behavior of resistive switching. In addition, Ag/MnPS3/Au and Ag/NiPS3/Au devices show synaptic characteristics of potentiation and depression. The digital and analog characteristics of resistance states enable Ag/MPS3/Au devices to work as both binary memory and artificial synapse devices. The Ag/MPS3/Au memory devices are promising for applications of flexible eye-like and brain-like systems on a chip when they are integrated with photodetectors and FETs composed of full MPS3 materials.
    Enhanced circular dichroism of plasmonic system in the strong coupling regime
    Yun-Fei Zou(邹云飞) and Li Yu(于丽)
    Chin. Phys. B, 2021, 30 (4):  047304.  DOI: 10.1088/1674-1056/abd6fd
    Abstract ( 178 )   HTML ( 0 )   PDF (3873KB) ( 27 )  
    The circular dichroism (CD) signal of a molecule is usually weak, however, a strong CD signal in optical spectrum is desirable because of its wide range of applications in biosensing, chiral photo detection, and chiral catalysis. In this work, we show that a strong chiral response can be obtained in a hybridized system consisting of an artificial chiral molecule and a nanorod in the strong coupling regime. The artificial chiral molecule is composed of six quantum dots in a helix assembly, and its CD signal arises from internal Coulomb interactions between quantum dots. The CD signal of the hybridized system is highly dependent on the Coulomb interactions and the strong coupling progress through the electromagnetic interactions. We use the coupled oscillator model to analyze strong coupling phenomenon and address that the strong coupling progress can amplify the CD signal. This work provides a scenario for designing new plasmonic nanostructures with a strong chiral optical response.
    Quantization of the band at the surface of charge density wave material 2H-TaSe2 Hot!
    Man Li(李满), Nan Xu(徐楠), Jianfeng Zhang(张建丰), Rui Lou(娄睿), Ming Shi(史明), Lijun Li(黎丽君), Hechang Lei(雷和畅), Cedomir Petrovic, Zhonghao Liu(刘中灏), Kai Liu(刘凯), Yaobo Huang(黄耀波), and Shancai Wang(王善才)
    Chin. Phys. B, 2021, 30 (4):  047305.  DOI: 10.1088/1674-1056/abe9a8
    Abstract ( 742 )   HTML ( 0 )   PDF (1794KB) ( 737 )  
    By using angle-resolved photoemission spectroscopy (ARPES) combined with the first-principles electronic structure calculations, we report the quantized states at the surface of a single crystal 2H-TaSe2. We have observed sub-bands of quantized states at the three-dimensional Brillouin zone center due to a highly dispersive band with light effective mass along kz direction. The quantized sub-bands shift upward towards EF while the bulk band at $\varGamma$ shifts downward with the decrease of temperature across charge density wave (CDW) formation. The band shifts could be intimately related to the CDW. While neither the two-dimensional Fermi-surface nesting nor purely strong electron-phonon coupling can explain the mechanism of CDW in 2H-TaSe2, our experiment may ignite the interest in understanding the CDW mechanism in this family.
    Device physics and design of FD-SOI JLFET with step-gate-oxide structure to suppress GIDL effect
    Bin Wang(王斌), Xin-Long Shi(史鑫龙), Yun-Feng Zhang(张云峰), Yi Chen(陈伊), Hui-Yong Hu(胡辉勇), and Li-Ming Wang(王利明)
    Chin. Phys. B, 2021, 30 (4):  047401.  DOI: 10.1088/1674-1056/abd2a2
    Abstract ( 309 )   HTML ( 0 )   PDF (713KB) ( 37 )  
    A novel n-type junctionless field-effect transistor (JLFET) with a step-gate-oxide (SGO) structure is proposed to suppress the gate-induced drain leakage (GIDL) effect and off-state current I off. Introducing a 6-nm-thick tunnel-gate-oxide and maintaining 3-nm-thick control-gate-oxide, lateral band-to-band tunneling (L-BTBT) width is enlarged and its tunneling probability is reduced at the channel-drain surface, leading the off-state current Ioff to decrease finally. Also, the thicker tunnel-gate-oxide can reduce the influence on the total gate capacitance of JLFET, which could alleviate the capacitive load of the transistor in the circuit applications. Sentaurus simulation shows that Ioff of the new optimized JLFET reduced significantly with little impaction on its on-state current I on and threshold voltage V TH becoming less, thus showing an improved Ion/Ioff ratio (5×104) and subthreshold swing (84 mV/dec), compared with the scenario of the normal JLFET. The influence of the thickness and length of SGO structure on the performance of JLFET are discussed in detail, which could provide useful instruction for the device design.
    Resistance fluctuations in superconducting KxFe2-ySe2 single crystals studied by low-frequency noise spectroscopy
    Hai Zi(子海), Yuan Yao(姚湲), Ming-Chong He(何明冲), Di Ke(可迪), Hong-Xing Zhan(詹红星), Yu-Qing Zhao(赵宇清), Hai-Hu Wen(闻海虎), and Cong Ren(任聪)
    Chin. Phys. B, 2021, 30 (4):  047402.  DOI: 10.1088/1674-1056/abf103
    Abstract ( 191 )   HTML ( 0 )   PDF (1390KB) ( 79 )  
    Low-frequency resistance noise spectroscopy is applied to investigate bulk single crystals of the intercalated iron-selenide KxFe2-ySe2 superconductors with different iron vacancy orders. Based on a generalized fluctuation model, the well-observed resistance hump above 100 K is interpreted as an insulator-metal phase transition with a characteristic transition energy of 0.1-0.6 eV, indicating a highly inhomogeneous energy distribution configuration. In the superconducting transition regime, we find that the normalized resistance noise scales with resistance R excellently as SR/R2Rl rs with the noise exponent lrs≈ 1.4. With reduced iron vacancy disordering in enhanced superconductivity KxFe2-ySe2 crystals, the level of resistance fluctuations is greatly suppressed, suggesting a geometrical phase transition for conduction channel, which is directly related to the microstructure of the crystals.
    Nodal superconducting gap in LiFeP revealed by NMR: Contrast with LiFeAs Hot!
    A F Fang(房爱芳), R Zhou(周睿), H Tukada, J Yang(杨杰), Z Deng(邓正), X C Wang(望贤成) , C Q Jin(靳常青), and Guo-Qing Zheng(郑国庆)
    Chin. Phys. B, 2021, 30 (4):  047403.  DOI: 10.1088/1674-1056/abec37
    Abstract ( 393 )   HTML ( 2 )   PDF (1513KB) ( 352 )  
    Identifying the uniqueness of FeP-based superconductors may shed new lights on the mechanism of superconductivity in iron-pnictides. Here, we report nuclear magnetic resonance (NMR) studies on LiFeP and LiFeAs which have the same crystal structure but different pnictogen atoms. The NMR spectrum is sensitive to inhomogeneous magnetic fields in the vortex state and can provide the information on the superconducting pairing symmetry through the temperature dependence of London penetration depth ΛL. We find that Λ L saturates below T ∼ 0.2 T c in LiFeAs, where T c is the superconducting transition temperature, indicating nodeless superconducting gaps. Furthermore, by using a two-gaps model, we simulate the temperature dependence of ΛL and obtain the superconducting gaps of LiFeAs, as $\varDelta_1 = 1.2$ kB Tc and $\varDelta_2 = 2.8$ kB T c, in agreement with previous result from spin-lattice relaxation. For LiFeP, in contrast, Λ L does not show any saturation down to T ∼ 0.03 T c, indicating nodes in the superconducting gap function. Finally, we demonstrate that strong spin fluctuations with diffusive characteristics exist in LiFeP, as in some cuprate high temperature superconductors.
    Magnetic anisotropy in 5d transition metal-porphyrin molecules
    Yan-Wen Zhang(张岩文), Gui-Xian Ge(葛桂贤), Hai-Bin Sun(孙海斌), Jue-Ming Yang(杨觉明), Hong-Xia Yan(闫红霞), Long Zhou(周龙), Jian-Guo Wan(万建国), and Guang-Hou Wang(王广厚)
    Chin. Phys. B, 2021, 30 (4):  047501.  DOI: 10.1088/1674-1056/abcf9c
    Abstract ( 197 )   HTML ( 0 )   PDF (1974KB) ( 19 )  
    Single molecule magnets (SMMs) with large magnetic anisotropy energy (MAE) have great potential applications in magnetic recording. Using the first-principles calculations, we investigate the MAE of 5d transition metal-porphyrin-based SMMs by using the PBE and PBE+U with different U values, respectively. The results indicate that W-P, Re-P, Os-P, and Ir-P possess the considerably large MAE among 5d TM-P SMMs. Furthermore, the MAE of 5d TM-P can be facilely manipulated by tensile strain. The reduction of the absolute value of MAE for Ir-P molecule caused by tensile strain makes it easier to implement the writing operation. The decreasing of the occupation number of minority-spin channels of Ir-dx2-y2 orbital leads the MAE to decrease when the tensile strain increases.
    Origin of itinerant ferromagnetism in two-dimensional Fe3GeTe2
    Xi Chen(陈熙), Zheng-Zhe Lin(林正喆), and Li-Rong Cheng(程丽蓉)
    Chin. Phys. B, 2021, 30 (4):  047502.  DOI: 10.1088/1674-1056/abd164
    Abstract ( 296 )   HTML ( 1 )   PDF (4118KB) ( 111 )  
    Magnetic order in two-dimensional systems was not supposed to exist at finite temperature. In recent years, the successful preparation of two-dimensional ferromagnetic materials such as CrI3, Cr2Ge2Te6, and Fe3GeTe2 opens up a new chapter in the remarkable field of two-dimensional materials. Here, we report on a theoretical analysis of the stability of ferromagnetism in Fe3GeTe2. We uncover the mechanism of holding long-range magnetic order and propose a model to estimate the Curie temperature of Fe3GeTe2. Our results reveal the essential role of magnetic anisotropy in maintaining the magnetic order of two-dimensional systems. The theoretical method used here can be generalized to future research of other magnetic two-dimensional systems.
    Spin correlations in the S=1 armchair chain Ni2NbBO6 as seen from NMR
    Kai-Yue Zeng(曾凯悦), Long Ma(马龙), Long-Meng Xu(徐龙猛), Zhao-Ming Tian(田召明), Lang-Sheng Ling(凌浪生), and Li Pi(皮雳)
    Chin. Phys. B, 2021, 30 (4):  047503.  DOI: 10.1088/1674-1056/abc2b5
    Abstract ( 152 )   HTML ( 0 )   PDF (1098KB) ( 27 )  
    We report our nuclear magnetic resonance (NMR) study on the structurally spin chain compound Ni2NbBO6 with complex magnetic coupling. The antiferromagnetic transition is monitored by the line splitting resulting from the staggered internal hyperfine field. The magnetic coupling configuration proposed by the first-principle density functional theory (DFT) is supported by NMR spectral analysis. For the spin dynamics, a prominent peak at T∼35 K well above the Néel temperature (T N∼20 K at μ0H=10 T) is observed from the spin-lattice relaxation data. As compared with the dc-susceptibility, this behavior indicates an antiferromagnetic coupling with the typical energy scale of ∼3 meV. Thus, the Ni2NbBO6 compound can be viewed as strongly ferromagnetically coupled armchair spin chains along the crystalline b-axis. These facts place strong constraints on the theoretical model for this compound.
    Experiments and SPICE simulations of double MgO-based perpendicular magnetic tunnel junction
    Qiuyang Li(李求洋), Penghe Zhang(张蓬鹤), Haotian Li(李浩天), Lina Chen(陈丽娜), Kaiyuan Zhou(周恺元), Chunjie Yan(晏春杰), Liyuan Li(李丽媛), Yongbing Xu(徐永兵), Weixin Zhang(张卫欣), Bo Liu(刘波), Hao Meng(孟浩), Ronghua Liu(刘荣华), and Youwei Du(都有为)
    Chin. Phys. B, 2021, 30 (4):  047504.  DOI: 10.1088/1674-1056/abdea2
    Abstract ( 264 )   HTML ( 0 )   PDF (823KB) ( 88 )  
    We investigate properties of perpendicular anisotropy magnetic tunnel junctions (pMTJs) with a stack structure MgO/CoFeB/Ta/CoFeB/MgO as the free layer (or recording layer), and obtain the necessary device parameters from the tunneling magnetoresistance (TMR) vs. field loops and current-driven magnetization switching experiments. Based on the experimental results and device parameters, we further estimate current-driven switching performance of pMTJ including switching time and power, and their dependence on perpendicular magnetic anisotropy and damping constant of the free layer by SPICE-based circuit simulations. Our results show that the pMTJ cells exhibit a less than 1 ns switching time and write energies < 1.4 pJ; meanwhile the lower perpendicular magnetic anisotropy (PMA) and damping constant can further reduce the switching time at the studied range of damping constant α < 0.1. Additionally, our results demonstrate that the pMTJs with the thermal stability factor $\simeq 73$ can be easily transformed into spin-torque nano-oscillators from magnetic memory as microwave sources or detectors for telecommunication devices.
    Texture analysis of ultra-high coercivity Sm2Co7 hot deformation magnets
    Qiang Ma(马强), Meishuang Jia(贾美爽), Zhifeng Hu(胡智峰), Ming Yue(岳明), Yanli Liu(刘艳丽), Tongyun Zhao(赵同云), and Baogen Shen(沈保根)
    Chin. Phys. B, 2021, 30 (4):  047505.  DOI: 10.1088/1674-1056/abe2fc
    Abstract ( 262 )   HTML ( 0 )   PDF (1269KB) ( 102 )  
    Bulk anisotropic Sm2Co7 nanocrystalline magnets were successfully prepared by hot deformation process using spark plasma sintering technology. The coercivity of the isotropic Sm2Co7 nanocrystalline magnet is 34.76 kOe, further, the ultra-high coercivity of 50.68 kOe is obtained in the anisotropic hot deformed Sm2Co7 magnet when the height reduction is 70%, which is much higher than those of the ordinarily produced hot deformed Sm2Co7 magnet. X-ray diffraction (XRD) analysis shows that all the samples are Sm2Co7 single phase. The investigation by electron backscatter diffraction indicates that increasing the amount of deformation is beneficial to the improvement of the (00l) texture of Sm2Co7 magnets. The Sm2Co7 nanocrystalline magnet generates a strong c-axis crystallographic texture during large deformation process.
    Combined effects of carrier scattering and Coulomb screening on photoluminescence in InGaN/GaN quantum well structure with high In content
    Rui Li(李睿), Ming-Sheng Xu(徐明升), Peng Wang(汪鹏), Cheng-Xin Wang(王成新), Shang-Da Qu(屈尚达), Kai-Ju Shi(时凯居), Ye-Hui Wei(魏烨辉), Xian-Gang Xu(徐现刚), and Zi-Wu Ji(冀子武)
    Chin. Phys. B, 2021, 30 (4):  047801.  DOI: 10.1088/1674-1056/abd692
    Abstract ( 207 )   HTML ( 3 )   PDF (2584KB) ( 22 )  
    Photoluminescence (PL) spectra of two different green InGaN/GaN multiple quantum well (MQW) samples S1 and S2, respectively with a higher growth temperature and a lower growth temperature of InGaN well layers are analyzed over a wide temperature range of 6 K-330 K and an excitation power range of 0.001 mW-75 mW. The excitation power-dependent PL peak energy and linewidth at 6 K show that in an initial excitation power range, the emission process of the MQW is dominated simultaneously by the combined effects of the carrier scattering and Coulomb screening for both the samples, and both the carrier scattering effect and the Coulomb screening effect are stronger for S2 than those for S1; in the highest excitation power range, the emission process of the MQWs is dominated by the filling effect of the high-energy localized states for S1, and by the Coulomb screening effect for S2. The behaviors can be attributed to the fact that sample S2 should have a higher amount of In content in the InGaN well layers than S1 because of the lower growth temperature, and this results in a stronger component fluctuation-induced potential fluctuation and a stronger well/barrier lattice mismatch-induced quantum-confined Stark effect. This explanation is also supported by other relevant measurements of the samples, such as temperature-dependent peak energy and excitation-power-dependent internal quantum efficiency.
    Optical polarization characteristics for AlGaN-based light-emitting diodes with AlGaN multilayer structure as well layer
    Lu Xue(薛露), Yi Li(李毅), Mei Ge(葛梅), Mei-Yu Wang(王美玉), and You-Hua Zhu(朱友华)
    Chin. Phys. B, 2021, 30 (4):  047802.  DOI: 10.1088/1674-1056/abcf3f
    Abstract ( 131 )   HTML ( 0 )   PDF (711KB) ( 17 )  
    The optical properties of AlGaN-based quantum well (QW) structure with two coupled thin well layers are investigated by the six-by-six K- P method. Compared with the conventional structure, the new structure, especially the one with lower Al-content in the barrier layer, can enhance the TE-/TM-polarized total spontaneous emission rate due to the strong quantum confinement and wide recombination region. For the conventional QW structure, the reduction of well thickness can lead the degree of polarization (DOP) to decrease and the internal quantum efficiency (IQE) to increase. By using the coupled thin well layers, the DOP for the structure with high Al-content in the barrier layer can be improved, while the DOP will further decrease with low Al-content in the barrier layer. It can be attributed to the band adjustment induced by the combination of barrier height and well layer coupling. The IQE can also be further enhanced to 14.8%-20.5% for various Al-content of barrier layer at J=100 A/cm2. In addition, the efficiency droop effect can be expected to be suppressed compared with the conventional structure.
    Adsorption of CO2 on MgAl layered double hydroxides: Effect of intercalated anion and alkaline etching time
    Yan-Yan Feng(冯艳艳), Xiao-Di Niu(牛潇迪), Yong-Hui Xu (徐永辉), and Wen Yang(杨文)
    Chin. Phys. B, 2021, 30 (4):  048101.  DOI: 10.1088/1674-1056/abd750
    Abstract ( 166 )   HTML ( 0 )   PDF (958KB) ( 16 )  
    The adsorption of CO2 on MgAl layered double hydroxides (MgAl-LDHs) based adsorbents has been an effective way to capture CO2, however the adsorption capacity was hampered due to the pore structure and the dispersibility of adsorption active sites. To address the problem, we investigate the effect of intercalated anion and alkaline etching time on the structure, morphology and CO2 uptake performances of MgAl-LDHs. MgAl-LDHs are synthesized by the one-pot hydrothermal method, followed by alkaline etching of NaOH, and characterized by x-ray diffraction, N2 adsorption, scanning electron microscopy and Fourier transform infrared spectroscopy. The CO2 adsorption tests of the samples are performed on a thermogravimetric analyzer, and the adsorption data are fitted by the first-order, pseudo-second-order and Elovich models, respectively. The results demonstrate that among the three intercalated samples, MgAl(Cl) using chloride salts as precursors possesses the highest adsorption capacity of CO2, owing to high crystallinity and porous structure, while MgAl(Ac) employing acetate salts as precursors displays the lowest CO2 uptake because of poor crystallinity, disorderly stacked structure and unsatisfactory pore structure. With regard to alkaline etching, the surface of the treated MgAl(Cl) is partly corroded, thus the specific surface area and pore volume increase, which is conducive to the exposure of adsorption active sites. Correspondingly, the adsorption performance of the alkaline-etched adsorbents is significantly improved, and MgAl(Cl)-6 has the highest CO2 uptake. With the alkaline etching time further increasing, the CO2 adsorption capacity of MgAl(Cl)-9 sharply decreases, mainly due to the collapse of pore structure and the fragmentized sheet-structure. Hence, the CO2 adsorption performance is greatly influenced by alkaline etching time, and appropriate alkaline etching time can facilitate the contact between CO2 molecules and the adsorbent.
    Intercalation of germanium oxide beneath large-area and high-quality epitaxial graphene on Ir(111) substrate
    Xueyan Wang(王雪艳), Hui Guo(郭辉), Jianchen Lu(卢建臣), Hongliang Lu(路红亮), Xiao Lin(林晓), Chengmin Shen(申承民), Lihong Bao(鲍丽宏), Shixuan Du(杜世萱), and Hong-Jun Gao(高鸿钧)
    Chin. Phys. B, 2021, 30 (4):  048102.  DOI: 10.1088/1674-1056/abe22c
    Abstract ( 241 )   HTML ( 0 )   PDF (1129KB) ( 111 )  
    Epitaxial growth on transition metal surfaces is an effective way to prepare large-area and high-quality graphene. However, the strong interaction between graphene and metal substrates suppresses the intrinsic excellent properties of graphene and the conductive metal substrates also hinder its applications in electronics. Here we demonstrate the decoupling of graphene from metal substrates by germanium oxide intercalation. Germanium is firstly intercalated into the interface between graphene and Ir(111) substrate. Then oxygen is subsequently intercalated, leading to the formation of a GeOx layer, which is confirmed by x-ray photoelectron spectroscopy. Low-energy electron diffraction and scanning tunneling microscopy studies show intact carbon lattice of graphene after the GeOx intercalation. Raman characterizations reveal that the intercalated layer effectively decouples graphene from the Ir substrate. The transport measurements demonstrate that the GeOx layer can act as a tunneling barrier in the fabricated large-area high-quality vertical graphene/GeOx/Ir heterostructure.
    Effect of hydrogen content on dielectric strength of the silicon nitride film deposited by ICP-CVD
    Yudong Zhang(张玉栋), Jiale Tang(唐家乐), Yongjie Hu(胡永杰), Jie Yuan(袁杰), Lulu Guan(管路路), Xingyu Li(李星雨), Hushan Cui(崔虎山), Guanghui Ding(丁光辉), Xinying Shi(石新颖), Kaidong Xu(许开东), and Shiwei Zhuang(庄仕伟)
    Chin. Phys. B, 2021, 30 (4):  048103.  DOI: 10.1088/1674-1056/abea82
    Abstract ( 277 )   HTML ( 3 )   PDF (648KB) ( 50 )  
    The inductively coupled plasma chemical vapor deposition (ICP-CVD) deposited silicon nitride (SiNx) thin film was evaluated for its application as the electrical insulating film for a capacitor device. In order to achieve highest possible dielectric strength of SiNx, the process parameters of ICP-CVD were carefully tuned to control hydrogen in SiNx films by means of tuning N2/SiH4 ratio and radio frequency (RF) power. Besides electrical measurements, the hydrogen content in the films was measured by dynamic secondary ion mass spectrometry (D-SIMS). Fourier transform infrared spectroscopy (FTIR) and micro Raman spectroscopy were used to characterize the SiNx films by measuring Si-H and N-H bonds' intensities. It was found that the more Si-H bonds lead to the higher dielectric strength.
    TOPICAL REVIEW—Quantum computation and quantum simulation
    Quantum simulations with nuclear magnetic resonance system
    Chudan Qiu(邱楚丹), Xinfang Nie(聂新芳), and Dawei Lu(鲁大为)
    Chin. Phys. B, 2021, 30 (4):  048201.  DOI: 10.1088/1674-1056/abe299
    Abstract ( 283 )   HTML ( 1 )   PDF (2301KB) ( 132 )  
    Thanks to the quantum simulation, more and more problems in quantum mechanics which were previously inaccessible are now open to us. Capitalizing on the state-of-the-art techniques on quantum coherent control developed in past few decades, e.g., the high-precision quantum gate manipulating, the time-reversal harnessing, the high-fidelity state preparation and tomography, the nuclear magnetic resonance (NMR) system offers a unique platform for quantum simulation of many-body physics and high-energy physics. Here, we review the recent experimental progress and discuss the prospects for quantum simulation realized on NMR systems.
    Grain boundary effect on structural, optical, and electrical properties of sol-gel synthesized Fe-doped SnO2 nanoparticles
    Archana V, Lakshmi Mohan, Kathirvel P, and Saravanakumar S
    Chin. Phys. B, 2021, 30 (4):  048202.  DOI: 10.1088/1674-1056/abc2c1
    Abstract ( 256 )   HTML ( 0 )   PDF (6121KB) ( 41 )  
    Tin oxide (SnO2) and iron-doped tin oxide (Sn1-xFexO2 , x = 0.05 wt%, 0.10 wt%) nanoparticles are synthesized by the simple sol-gel method. The structural characterization using x-ray diffraction (XRD) confirms tetragonal rutile phases of the nanoparticles. The variations in lattice parameters and relative intensity with Fe-doping concentration validate the incorporation of iron into the lattice. The compressive strain present in the lattice estimated by using peak profile analysis through using Williamson-Hall plot also exhibits the influence of grain boundary formation in the lattice. The radiative recombination and quenching observed in optical characterization by using photoluminescence spectrum (PL) and the shift in the band gap estimated from UV-visible diffused reflectance spectrum corroborate the grain boundary influence. Raman spectrum and the morphological analysis by using a field emission scanning electron microscope (FESEM) also indicate the formation of grain boundaries. The compositional analysis by using energy dispersive x-ray spectrum (EDAX) confirms Fe in the SnO2 lattice. The conductivity studies exhibit that the impendence increases with doping concentration increasing and the loss factor decreases at high frequencies with doping concentration increasing, which makes the Sn1-xFexO2 a potential candidate for device applications.
    Phase transition of asymmetric diblock copolymer induced by nanorods of different properties
    Yu-Qi Guo(郭宇琦)
    Chin. Phys. B, 2021, 30 (4):  048301.  DOI: 10.1088/1674-1056/abcf3c
    Abstract ( 189 )   HTML ( 0 )   PDF (4418KB) ( 21 )  
    We investigate the microphase transition of asymmetric diblock copolymer induced by nanorods of different properties using cell dynamics simulation and Brown dynamics. The results show the phase diagram and representative nanostructures of the diblock copolymer nanocomposite. Various structures such as sea-island structure (SI), sea-island and lamellar structure (SI-L), and lamellar structure (L) are observed in the phase diagram. The system undergoes phase transition from SI-L to SI or from L to SI with increasing length of A-like sites for all numbers of nanorods except 10 and 300, and from SI to L with increasing number of nanorods for all lengths of A-like sites. Notably, the polymer system transforms from a tilted layered structure to a parallel lamellar, perpendicular lamellar, and subsequently sea-island structure with increasing length of A-like sites for a rod number of 240. To gain more detailed insight into these structural formation mechanisms, we analyze the evolution kinetics of the system with various lengths of A-like sites of the rods. The pattern evolution and domain growth of the ordered parallel/perpendicular lamellar structure are also investigated. Furthermore, the effects of the wetting strength, rod-rod interaction, polymerization degree, and length of nanorods on the self-assembled structure of asymmetric diblock copolymer/nanorods are studied. Our simulations provide theoretical guidance on the construction of complex-assembled structures and the design of novel functional materials.
    Design and optimization of nano-antenna for thermal ablation of liver cancer cells
    Mohammad Javad Rabienejhad, Azardokht Mazaheri, and Mahdi Davoudi-Darareh
    Chin. Phys. B, 2021, 30 (4):  048401.  DOI: 10.1088/1674-1056/abd38e
    Abstract ( 165 )   HTML ( 0 )   PDF (2657KB) ( 32 )  
    One method of cancer therapy is to utilize nano-antenna for thermal ablation. In this method, the electromagnetic waves emitted from the nano-antenna are absorbed by the tissue and lead to heating of cancer cells. If temperature of cancer cells reaches a threshold, they will begin to die. For this purpose, an L-shaped frame nano-antenna (LSFNA) is designed to introduce into the biological tissue. Thus, the radiation characteristics of the LSFNA such as near and far-field intensities, directivity, and sensitivity to its gap width are studied to the optimization of the nano-antenna. The bio-heat and Maxwell equations are solved using the finite element method. To prevent damage to healthy tissues in this method, the antenna radiation must be completely controlled and performed carefully. Thus, penetration depth, special absorption rate, temperature distribution, and the fraction of tissue necrosis are analyzed in the biological tissue. That is why the design and optimization of the nano-antennas as a radiation source is important. Also, a pulsed source is used to excite the LSFNA. Furthermore, focusing and efficiency of the nano-antenna radiation on the cancer cell is tuned using an adjustable liquid crystal lens. The focus of this lens is changing under an electric field applied to its surrounding cathode.
    Convolutional neural network for transient grating frequency-resolved optical gating trace retrieval and its algorithm optimization
    Siyuan Xu(许思源), Xiaoxian Zhu(朱孝先), Ji Wang(王佶), Yuanfeng Li(李远锋), Yitan Gao(高亦谈), Kun Zhao(赵昆), Jiangfeng Zhu(朱江峰), Dacheng Zhang(张大成), Yunlin Chen(陈云琳), and Zhiyi Wei(魏志义)
    Chin. Phys. B, 2021, 30 (4):  048402.  DOI: 10.1088/1674-1056/abf0ff
    Abstract ( 207 )   HTML ( 0 )   PDF (629KB) ( 23 )  
    A convolutional neural network is employed to retrieve the time-domain envelop and phase of few-cycle femtosecond pulses from transient-grating frequency-resolved optical gating (TG-FROG) traces. We use theoretically generated TG-FROG traces to complete supervised trainings of the convolutional neural networks, then use similarly generated traces not included in the training dataset to test how well the networks are trained. Accurate retrieval of such traces by the neural network is realized. In our case, we find that networks with exponential linear unit (ELU) activation function perform better than those with leaky rectified linear unit (LRELU) and scaled exponential linear unit (SELU). Finally, the issues that need to be addressed for the retrieval of experimental data by this method are discussed.
    Controllable microwave frequency comb generation in a tunable superconducting coplanar-waveguide resonator
    Shuai-Peng Wang(王帅鹏), Zhen Chen(陈臻), and Tiefu Li(李铁夫)
    Chin. Phys. B, 2021, 30 (4):  048501.  DOI: 10.1088/1674-1056/abc2bb
    Abstract ( 195 )   HTML ( 0 )   PDF (1231KB) ( 38 )  
    Frequency combs are useful in a wide range of applications, such as optical metrology and high-precision spectroscopy. We experimentally study a controllable frequency comb generated in a tunable superconducting coplanar-waveguide resonator in the microwave regime. A two-tone drive is applied on one of the resonance modes of the resonator and comb generation is observed around the resonance frequency of the resonator. Both central frequency and teeth density of the comb are precisely controllable, and the teeth spacing can be adjusted from Hz to MHz. Moreover, we show that a few hundreds of sidebands can be generated using a sufficiently strong drive power and the weakest drive power needed to generate the comb can be reduced to approach the quantum limit. These experimental results can be qualitatively explained via theoretical analysis.
    Influences of supply voltage on single event upsets and multiple-cell upsets in nanometer SRAM across a wide linear energy transfer range
    Yin-Yong Luo(罗尹虹), Wei Chen(陈伟), Feng-Qi Zhang(张凤祁), and Tan Wang(王坦)
    Chin. Phys. B, 2021, 30 (4):  048502.  DOI: 10.1088/1674-1056/abcf38
    Abstract ( 187 )   HTML ( 1 )   PDF (1199KB) ( 18 )  
    The influences of reducing the supply voltage on single event upset (SEU) and multiple-cell upset (MCU) in two kinds of 65-nm static random access memories (SRAMs) are characterized across a wide linear energy transfer (LET) range. The results show that the influence of the voltage variation on SEU cross section clearly depends on the LET value which is above heavy ion LET threshold no matter whether the SRAM is non-hardened 6T SRAM or radiation-hardened double dual interlocked cells (DICE) SRAM. When the LET value is lower than the LET threshold of MCU, the SEU only manifests single cell upset, the SEU cross section increases with the decrease of voltage. The lower the LET value, the higher the SEU sensitivity to the voltage variation is. Lowering the voltage has no evident influence on SEU cross section while the LET value is above the LET threshold of MCU. Moreover, the reduction of the voltage can result in a decrease in the highest-order MCU event cross section due to the decrease of charge collection efficiency of the outer sub-sensitive volume within a certain voltage range. With further scaling the feature size of devices down, it is suggested that the dependence of SEU on voltage variation should be paid special attention to for heavy ions with very low LET or the other particles with very low energy for nanometer commercial off-the-shelf (COTS) SRAM.
    Novel Si/SiC heterojunction lateral double-diffused metal-oxide semiconductor field-effect transistor with p-type buried layer breaking silicon limit
    Baoxing Duan(段宝兴), Xin Huang(黄鑫), Haitao Song (宋海涛), Yandong Wang(王彦东), and Yintang Yang(杨银堂)
    Chin. Phys. B, 2021, 30 (4):  048503.  DOI: 10.1088/1674-1056/abcf45
    Abstract ( 179 )   HTML ( 0 )   PDF (753KB) ( 35 )  
    A novel silicon carbide (SiC) on silicon (Si) heterojunction lateral double-diffused metal-oxide semiconductor field-effect transistor with p-type buried layer (PBL Si/SiC LDMOS) is proposed in this paper for the first time. The heterojunction has breakdown point transfer (BPT) characteristics, and the BPT terminal technology is used to increase the breakdown voltage (BV) of Si/SiC LDMOS with the deep drain region. In order to further optimize the surface lateral electric field distribution of Si/SiC LDMOS with the deep drain region, the p-type buried layer is introduced in PBL Si/SiC LDMOS. The vertical electric field is optimized by Si/SiC heterojunction and the surface lateral electric field is optimized by the p-type buried layer, which greatly improves the BV of device and alleviates the relationship between BV and specific on-resistance (R on,sp). Through TCAD simulation, when the drift region length is 20 μ m, the BV is significantly improved from 249 V for the conventional Si LDMOS to 440 V for PBL Si/SiC LDMOS, increased by 77%; And the BV is improved from 384 V for Si/SiC LDMOS with the deep drain region to 440 V for the proposed structure, increased by 15%. The figure-of-merit (FOM) of the Si/SiC LDMOS with the deep drain region and PBL Si/SiC LDMOS are 4.26 MW/cm2 and 6.37 MW/cm2, respectively. For the PBL Si/SiC LDMOS with the drift length of 20 μ m, the maximum FOM is 6.86 MW/cm2. The PBL Si/SiC LDMOS breaks conventional silicon limit.
    Characteristics and mechanisms of subthreshold voltage hysteresis in 4H-SiC MOSFETs
    Xi-Ming Chen(陈喜明), Bang-Bing Shi(石帮兵), Xuan Li(李轩), Huai-Yun Fan(范怀云), Chen-Zhan Li(李诚瞻), Xiao-Chuan Deng(邓小川), Hai-Hui Luo(罗海辉), Yu-Dong Wu(吴煜东), and Bo Zhang(张波)
    Chin. Phys. B, 2021, 30 (4):  048504.  DOI: 10.1088/1674-1056/abd391
    Abstract ( 267 )   HTML ( 0 )   PDF (790KB) ( 70 )  
    In order to investigate the characteristics and mechanisms of subthreshold voltage hysteresis (∆ V th, sub) of 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs), 4H-SiC planar and trench MOSFETs and corresponding P-type planar and trench metal-oxide-semiconductor (MOS) capacitors are fabricated and characterized. Compared with planar MOSFEF, the trench MOSFET shows hardly larger ∆ V th, sub in wide temperature range from 25 °C to 300 °C. When operating temperature range is from 25 °C to 300 °C, the off-state negative V gs of planar and trench MOSFETs should be safely above -4 V and -2 V, respectively, to alleviate the effect of ∆ V th, sub on the normal operation. With the help of P-type planar and trench MOS capacitors, it is confirmed that the obvious ∆ V th, sub of 4H-SiC MOSFET originates from the high density of the hole interface traps between intrinsic Fermi energy level (E i) and valence band (E v). The maximum ∆ V th, sub of trench MOSFET is about twelve times larger than that of planar MOSFET, owing to higher density of interface states (D it) between E i and E v. These research results will be very helpful for the application of 4H-SiC MOSFET and the improvement of ∆ V th, sub of 4H-SiC MOSFET, especially in 4H-SiC trench MOSFET.
    A new algorithm based on C-V characteristics to extract the epitaxy layer parameters for power devices with the consideration of termination
    Jiupeng Wu(吴九鹏), Na Ren(任娜), and Kuang Sheng(盛况)
    Chin. Phys. B, 2021, 30 (4):  048505.  DOI: 10.1088/1674-1056/abcf9e
    Abstract ( 146 )   HTML ( 0 )   PDF (2285KB) ( 21 )  
    Doping concentration and thickness of an epitaxy layer are the most essential parameters for power devices. The conventional algorithm extracts these two parameters by calculating the doping profile from its capacitance-voltage (C-V) characteristics. Such an algorithm treats the device as a parallel-plane junction and ignores the influence of the terminations. The epitaxy layer doping concentration tends to be overestimated and the thickness underestimated. In order to obtain the epitaxy layer parameters with higher accuracy, a new algorithm applicable for devices with field limited ring (FLR) terminations is proposed in this paper. This new algorithm is also based on the C-V characteristics and considers the extension manner of the depletion region under the FLR termination. Such an extension manner depends on the design parameters of the FLR termination and is studied in detail by simulation and modeling. The analytical expressions of the device C-V characteristics and the effective doping profile are derived. More accurate epitaxy layer parameters can be extracted by fitting the effective doping profile expression to the C-V doping profile calculated from the C-V characteristics. The relationship between the horizontal extension width and the vertical depth of the depletion region is also acquired. The credibility of the new algorithm is verified by experiments. The applicability of our new algorithm to FLR/field plate combining terminations is also discussed. Our new algorithm acts as a powerful tool for analyses and improvements of power devices.
    Performance and stability-enhanced inorganic perovskite light-emitting devices by employing triton X-100
    Ao Chen(陈翱), Peng Wang(王鹏), Tao Lin(林涛), Ran Liu(刘然), Bo Liu(刘波), Quan-Jun Li(李全军), and Bing-Bing Liu(刘冰冰)
    Chin. Phys. B, 2021, 30 (4):  048506.  DOI: 10.1088/1674-1056/abcf47
    Abstract ( 160 )   HTML ( 0 )   PDF (1064KB) ( 22 )  
    Significantly enhanced electroluminescence performance and stability of all-inorganic perovskite light-emitting devices (PeLEDs) have been achieved by adding triton X-100 into the perovskite precursors. The small perovskite grains arranged tightly and formed large grains as the triton X-100 were introduced. Thus the nonradiative defects originated from Pb atoms at the grain boundaries were highly passivated by triton X-100 and resulted in the promotion of PeLED performance, including a turn-on voltage of 3.2 V, a brightness of 63500 cd/m2, a current efficiency of 17.4 cd/A, and a prolonged lifetime of 2 h in air.
    SPECIAL TOPIC—Quantum computation and quantum simulation
    Micro-scale photon source in a hybrid cQED system
    Ming-Bo Chen(陈明博), Bao-Chuan Wang(王保传), Si-Si Gu(顾思思), Ting Lin(林霆), Hai-Ou Li(李海欧), Gang Cao(曹刚), and Guo-Ping Guo(郭国平)
    Chin. Phys. B, 2021, 30 (4):  048507.  DOI: 10.1088/1674-1056/abe29b
    Abstract ( 223 )   HTML ( 0 )   PDF (803KB) ( 61 )  
    Coherent photon source is an important element that has been widely used in spectroscopy, imaging, detection, and teleportation in quantum optics. However, it is still a challenge to realize micro-scale coherent emitters in semiconductor systems. We report the observation of gain in a cavity-coupled GaAs double quantum dot system with a voltage bias across the device. By characterizing and analyzing the cavity responses to different quantum dot behaviors, we distinguish the microwave photon emission from the signal gain. This study provides a possibility to realize micro-scale amplifiers or coherent microwave photon sources in circuit quantum electrodynamics (cQED) hybrid systems.
    GEANT4 simulation study of over-response phenomenon of fiber x-ray sensor
    Bin Zhang(张彬), Tian-Ci Xie(谢天赐), Zhuang Qin(秦壮), Hao-Peng Li(李昊鹏), Song Li(李松), Wen-Hui Zhao(赵文辉), Zi-Yin Chen(陈子印), Jun Xu(徐军), Elfed Lewis, and Wei-Min Sun(孙伟民)
    Chin. Phys. B, 2021, 30 (4):  048701.  DOI: 10.1088/1674-1056/abcfa6
    Abstract ( 240 )   HTML ( 0 )   PDF (1041KB) ( 51 )  
    The purpose of this article is to explore the cause of the over-response phenomenon of fiber x-ray sensor. The sensor is based on a length of PMMA fiber, whose end is filled with the scintillation material Gd2O2S:Tb. The Monte Carlo simulation software GEANT4 uses the phase space file provided by the International Atomic Energy Agency (IAEA), by irradiating the fiber x-ray sensor in the water phantom, counting the fluorescence signal of the optical fiber x-ray sensor after propagation through the fiber. In addition, the number of Cerenkov photons propagating through the fiber is also counted. Comparing this article with previous research, we believe that one of the reasons for the over-response of the fiber x-ray sensor is the non-linear response of the deposition energy of the scintillator to the fluorescence. By establishing a region of interest and counting the x-rays in this region, the simulation results show that the counted number of x-rays that may affect the fiber x-ray sensor is the biggest in the area of interest at a water depth of 5 cm. This result is close to the maximum dose point of the experimental and simulated percentage depth dose (PDD) curve of fiber x-ray sensor. Therefore, the second reason of the over-response phenomenon is believed to be fact that the inorganic materials such as Gd2O2S:Tb have larger effective atomic numbers, so the fiber x-ray sensors will cause more collisions with x-ray in a low energy region of 0.1 MeV-1.5 MeV.
    SPECIAL TOPIC—Machine learning in statistical physics
    Relationship between manifold smoothness and adversarial vulnerability in deep learning with local errors
    Zijian Jiang(蒋子健), Jianwen Zhou(周健文), and Haiping Huang(黄海平)
    Chin. Phys. B, 2021, 30 (4):  048702.  DOI: 10.1088/1674-1056/abd68e
    Abstract ( 284 )   HTML ( 10 )   PDF (1573KB) ( 70 )  
    Artificial neural networks can achieve impressive performances, and even outperform humans in some specific tasks. Nevertheless, unlike biological brains, the artificial neural networks suffer from tiny perturbations in sensory input, under various kinds of adversarial attacks. It is therefore necessary to study the origin of the adversarial vulnerability. Here, we establish a fundamental relationship between geometry of hidden representations (manifold perspective) and the generalization capability of the deep networks. For this purpose, we choose a deep neural network trained by local errors, and then analyze emergent properties of the trained networks through the manifold dimensionality, manifold smoothness, and the generalization capability. To explore effects of adversarial examples, we consider independent Gaussian noise attacks and fast-gradient-sign-method (FGSM) attacks. Our study reveals that a high generalization accuracy requires a relatively fast power-law decay of the eigen-spectrum of hidden representations. Under Gaussian attacks, the relationship between generalization accuracy and power-law exponent is monotonic, while a non-monotonic behavior is observed for FGSM attacks. Our empirical study provides a route towards a final mechanistic interpretation of adversarial vulnerability under adversarial attacks.
    Exploring individuals' effective preventive measures against epidemics through reinforcement learning
    Ya-Peng Cui(崔亚鹏), Shun-Jiang Ni (倪顺江), and Shi-Fei Shen(申世飞)
    Chin. Phys. B, 2021, 30 (4):  048901.  DOI: 10.1088/1674-1056/abcfa5
    Abstract ( 239 )   HTML ( 0 )   PDF (822KB) ( 55 )  
    Individuals' preventive measures, as an effective way to suppress epidemic transmission and to protect themselves from infection, have attracted much academic concern, especially during the COVID-19 pandemic. In this paper, a reinforcement learning-based model is proposed to explore individuals' effective preventive measures against epidemics. Through extensive simulations, we find that the cost of preventive measures influences the epidemic transmission process significantly. The infection scale increases as the cost of preventive measures grows, which means that the government needs to provide preventive measures with low cost to suppress the epidemic transmission. In addition, the effective preventive measures vary from individual to individual according to the social contacts. Individuals who contact with others frequently in daily life are highly recommended to take strict preventive measures to protect themselves from infection, while those who have little social contacts do not need to take any measures considering the inevitable cost. Our research contributes to exploring the effective measures for individuals, which can provide the government and individuals useful suggestions in response to epidemics.
    Wave-activity relation containing wave-basic flow interaction based on decomposition of general potential vorticity
    Na Li(李娜), Ling-Kun Ran(冉令坤), and Bao-Feng Jiao(焦宝峰)
    Chin. Phys. B, 2021, 30 (4):  049201.  DOI: 10.1088/1674-1056/abcf37
    Abstract ( 169 )   HTML ( 0 )   PDF (1566KB) ( 18 )  
    On the basis of the general potential vorticity theorem (GPV), a new wave-activity relation is derived in an ageostrophic and nonhydrostatic dynamic framework. When the Reynolds average is taken, the wave-activity relation shares an exchange term with the equation of the basic-state GPV. Thus, the two equations are capable of presenting the dynamic process of the wave-basic flow interaction. Unlike the E-P flux theory which can only be used in large-scale atmosphere, the corresponding derivation provides a useful tool to analyze the feedback of waves to basic states and the forcing of basic states to waves simultaneously, and it can be used in mesoscale systems, such as heavy rainfall processes. The theory was initially applied to the landfalling Typhoon Mujigae (2015) by assigning the scalar φ to the generalized potential temperature (GPT). The results showed that the newly-derived wave-activity density is able to describe the wave activities associated with strong precipitation in Typhoon Mujigae (2015), including the eyewall and spiral rainbands. However, the interaction between the basic-state vortex and mesoscale waves denoted by the exchange term between basic-state GPV and wave-activity density mainly occurs in the eyewall in Typhoon Mujigae (2015). A comparison of the exchange term with other forcing terms in the newly-derived wave-activity relation indicates that the basic state-wave interaction plays a significant role in enhancing wave activities in the high-precipitation eyewall. By a magnitude analysis of the interaction term, it is found that the strong interaction between basic-state vortex and mesoscale waves is mainly attributed to two factors: the vertical vorticity intensity of the basic-state vortex and the averaged perturbation advection of perturbation GPT which is an exchange between the basic-state GPT and perturbation GPT.
ISSN 1674-1056   CN 11-5639/O4
, Vol. 30, No. 4

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