Chinese Physics B最新文献

{"title":"Computing large deviation prefactors of stochastic dynamical systems based on machine learning","authors":"Yang Li, Shenglan Yuan, Linghongzhi Lu, Xianbin Liu","doi":"10.1088/1674-1056/ad12a8","DOIUrl":"https://doi.org/10.1088/1674-1056/ad12a8","url":null,"abstract":"We present a large deviation theory that characterizes the exponential estimate for rare events in stochastic dynamical systems in the limit of weak noise. We aim to consider a next-to-leading-order approximation for more accurate calculation of the mean exit time by computing large deviation prefactors with the aid of machine learning. More specifically, we design a neural network framework to compute quasipotential, most probable paths and prefactors based on the orthogonal decomposition of a vector field. We corroborate the higher effectiveness and accuracy of our algorithm with two toy models. Numerical experiments demonstrate its powerful functionality in exploring the internal mechanism of rare events triggered by weak random fluctuations.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"128 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140614236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tunable superconducting resonators via on-chip control of local magnetic field","authors":"Chen-Guang Wang, Wen-Cheng Yue, Xuecou Tu, Tianyuan Chi, Tingting Guo, Yang-Yang Lyu, Sining Dong, Chunhai Cao, Labao Zhang, Xiaoqing Jia, Guozhu Sun, Lin Kang, Jian Chen, Yong-Lei Wang, Huabing Wang, Peiheng Wu","doi":"10.1088/1674-1056/ad2f21","DOIUrl":"https://doi.org/10.1088/1674-1056/ad2f21","url":null,"abstract":"Superconducting microwave resonators play a pivotal role in superconducting quantum circuits. The ability to fine-tune their resonant frequencies provides enhanced control and flexibility. Here, we introduce a frequency-tunable superconducting coplanar waveguide resonator. By applying electrical currents through specifically designed ground wires, we achieve the generation and control of a localized magnetic field on the central line of the resonator, enabling continuous tuning of its resonant frequency. We demonstrate a frequency tuning range of 54.85 MHz in a 6.21-GHz resonator. This integrated and tunable resonator holds great potential as a dynamically tunable filter and as a key component of communication buses and memory elements in superconducting quantum computing.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quafu-Qcover: Explore combinatorial optimization problems on cloud-based quantum computers","authors":"Hong-Ze Xu, Wei-Feng Zhuang, Zheng-An Wang, Kai-Xuan Huang, Yun-Hao Shi, Wei-Guo Ma, Tian-Ming Li, Chi-Tong Chen, Kai Xu, Yu-Long Feng, Pei Liu, Mo Chen, Shang-Shu Li, Zhi-Peng Yang, Chen Qian, Yu-Xin Jin, Yun-Heng Ma, Xiao Xiao, Peng Qian, Yanwu Gu, Xu-Dan Chai, Ya-Nan Pu, Yi-Peng Zhang, Shi-Jie Wei, Jin-Feng Zeng, Hang Li, Gui-Lu Long, Yirong Jin, Haifeng Yu, Heng Fan, Dong E. Liu, Meng-Jun Hu","doi":"10.1088/1674-1056/ad18ab","DOIUrl":"https://doi.org/10.1088/1674-1056/ad18ab","url":null,"abstract":"We introduce Quafu-Qcover, an open-source cloud-based software package developed for solving combinatorial optimization problems using quantum simulators and hardware backends. Quafu-Qcover provides a standardized and comprehensive workflow that utilizes the quantum approximate optimization algorithm (QAOA). It facilitates the automatic conversion of the original problem into a quadratic unconstrained binary optimization (QUBO) model and its corresponding Ising model, which can be subsequently transformed into a weight graph. The core of Qcover relies on a graph decomposition-based classical algorithm, which efficiently derives the optimal parameters for the shallow QAOA circuit. Quafu-Qcover incorporates a dedicated compiler capable of translating QAOA circuits into physical quantum circuits that can be executed on Quafu cloud quantum computers. Compared to a general-purpose compiler, our compiler demonstrates the ability to generate shorter circuit depths, while also exhibiting superior speed performance. Additionally, the Qcover compiler has the capability to dynamically create a library of qubits coupling substructures in real-time, utilizing the most recent calibration data from the superconducting quantum devices. This ensures that computational tasks can be assigned to connected physical qubits with the highest fidelity. The Quafu-Qcover allows us to retrieve quantum computing sampling results using a task ID at any time, enabling asynchronous processing. Moreover, it incorporates modules for results preprocessing and visualization, facilitating an intuitive display of solutions for combinatorial optimization problems. We hope that Quafu-Qcover can serve as an instructive illustration for how to explore application problems on the Quafu cloud quantum computers.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"39 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140806801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Localization effect in single crystal of RuAs2","authors":"Zhe-Kai Yi, Qi Liu, Shuang-Kui Guang, Sheng Xu, Xiao-Yu Yue, Hui Liang, Na Li, Ying Zhou, Dan-Dan Wu, Yan Sun, Qiu-Ju Li, Peng Cheng, Tian-Long Xia, Xue-Feng Sun, Yi-Yan Wang","doi":"10.1088/1674-1056/ad23d9","DOIUrl":"https://doi.org/10.1088/1674-1056/ad23d9","url":null,"abstract":"We report the magnetotransport and thermal properties of RuAs₂ single crystal. RuAs₂ exhibits semiconductor behavior and localization effect. The crossover from normal state to diffusive transport in the weak localization (WL) state and then to variable range hopping (VRH) transport in the strong localization state has been observed. The transitions can be reflected in the measurement of resistivity and Seebeck coefficient. Negative magnetoresistance (NMR) emerges with the appearance of localization effect and is gradually suppressed in high magnetic field. The temperature dependent phase coherence length extracted from the fittings of NMR also indicates the transition from WL to VRH. The measurement of Hall effect reveals an anomaly of temperature dependent carrier concentration caused by localization effect. Our findings show that RuAs₂ is a suitable platform to study the localized state.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"22 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140311823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Image segmentation of exfoliated two-dimensional materials by generative adversarial network-based data augmentation","authors":"Xiaoyu Cheng, Chenxue Xie, Yulun Liu, Ruixue Bai, Nanhai Xiao, Yanbo Ren, Xilin Zhang, Hui Ma, Chongyun Jiang","doi":"10.1088/1674-1056/ad23d8","DOIUrl":"https://doi.org/10.1088/1674-1056/ad23d8","url":null,"abstract":"Mechanically cleaved two-dimensional materials are random in size and thickness. Recognizing atomically thin flakes by human experts is inefficient and unsuitable for scalable production. Deep learning algorithms have been adopted as an alternative, nevertheless a major challenge is a lack of sufficient actual training images. Here we report the generation of synthetic two-dimensional materials images using StyleGAN3 to complement the dataset. DeepLabv3Plus network is trained with the synthetic images which reduces overfitting and improves recognition accuracy to over 90%. A semi-supervisory technique for labeling images is introduced to reduce manual efforts. The sharper edges recognized by this method facilitate material stacking with precise edge alignment, which benefits exploring novel properties of layered-material devices that crucially depend on the interlayer twist-angle. This feasible and efficient method allows for the rapid and high-quality manufacturing of atomically thin materials and devices.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"28 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140311940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BaTiO3/p-GaN/Au self-driven UV photodetector with bipolar photocurrent controlled by ferroelectric polarization","authors":"Wushuang Han, Kewei Liu, Jialin Yang, Yongxue Zhu, Zhen Cheng, Xing Chen, Binghui Li, Lei Liu, Dezhen Shen","doi":"10.1088/1674-1056/ad2607","DOIUrl":"https://doi.org/10.1088/1674-1056/ad2607","url":null,"abstract":"Ferroelectric materials are promising candidates for ultraviolet photodetectors due to their ferroelectric effect. In this work, a BaTiO₃/p-GaN/Au hybrid heterojunction–Schottky self-driven ultraviolet photodetector was fabricated with excellent bipolar photoresponse property. At 0 V bias, the direction of the photocurrent can be switched by flipping the depolarization field of BaTiO₃, which allows the performance of photodetectors to be controlled by the ferroelectric effect. Meanwhile, a relatively large responsivity and a fast response speed can be also observed. In particular, when the depolarization field of BaTiO₃ is in the same direction of the built-in electric field of the Au/p-GaN Schottky junction (up polarized state), the photodetector exhibits a high responsivity of 18 mA/W at 360 nm, and a fast response speed of < 40 ms at 0 V. These findings pave a new way for the preparation of high-performance photodetectors with bipolar photocurrents.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"39 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140560702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stable photocurrent–voltage characteristics of perovskite single crystal detectors obtained by pulsed bias","authors":"Xin Liu, Zhi-Long Chen, Hu Wang, Wen-Qing Zhang, Hao Dong, Peng-Xiang Wang, Yu-Chuan Shao","doi":"10.1088/1674-1056/ad23d7","DOIUrl":"https://doi.org/10.1088/1674-1056/ad23d7","url":null,"abstract":"Photocurrent–voltage characterization is a crucial method for assessing key parameters in x-ray or <italic toggle=\"yes\">γ</italic>-ray semiconductor detectors, especially the carrier mobility lifetime product. However, the high biases during photocurrent measurements tend to cause severe ion migration, which can lead to the instability and inaccuracy of the test results. Given the mixed electronic–ionic characteristics, it is imperative to devise novel methods capable of precisely measuring photocurrent–voltage characteristics under high bias conditions, free from interference caused by ion migration. In this paper, pulsed bias is employed to explore the photocurrent–voltage characteristics of MAPbBr₃ single crystals. The method yields stable photocurrent–voltage characteristics at a pulsed bias of up to 30 V, proving to be effective in mitigating ion migration. Through fitting the modified Hecht equation, we determined the mobility lifetime products of 1.0 × 10⁻² cm²⋅V⁻¹ for hole and 2.78 × 10⁻³ cm²⋅V⁻¹ for electron. This approach offers a promising solution for accurately measuring the transport properties of carriers in perovskite.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"33 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140312155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling the performance of perovskite solar cells with inserting porous insulating alumina nanoplates","authors":"Zhaoyao Pan, Jinpeng Yang, Xiaoshuang Shen","doi":"10.1088/1674-1056/ad1480","DOIUrl":"https://doi.org/10.1088/1674-1056/ad1480","url":null,"abstract":"Peng <italic toggle=\"yes\">et al.</italic> [<italic toggle=\"yes\">Science</italic> <bold>379</bold> 683 (2023)] reported an effective method to improve the performance of perovskite solar cells by using thicker porous insulator contact (PIC)-alumina nanoplates. This method overcomes the trade-off between the open-circuit voltage and the fill factor through two mechanisms: reduced surface recombination velocity and increased bulk recombination lifetime due to better perovskite crystallinity. From arguments of drift-diffusion simulations, we find that an increase in mobility and carrier recombination lifetime in bulk are the key factors for minimizing the resistance-effect from thicker PICs and achieving a maximum power conversion efficiency (PCE) at approximately 25% reduced contact area. Furthermore, the partially replacement of perovskite films with thicker PICs would result in a reduction in short-current density, but the relative low refractive index of the PICs imbedded into the high refractive index perovskite creates light trapping structures that compensate for this loss.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"33 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140312115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetic diagnostics layout design for CFETR plasma equilibrium reconstruction","authors":"Qingze Yu, Yao Huang, Zhengping Luo, Yuehang Wang, Zijie Liu, Wangyi Rui, Kai Wu, Bingjia Xiao, Jiangang Li","doi":"10.1088/1674-1056/ad23d6","DOIUrl":"https://doi.org/10.1088/1674-1056/ad23d6","url":null,"abstract":"Plasma equilibrium reconstruction provides essential information for tokamak operation and physical analysis. An extensive and reliable set of magnetic diagnostics is required to obtain accurate plasma equilibrium. This study designs and optimizes the magnetic diagnostics layout for the reconstruction of the equilibrium of the plasma according to the scientific objectives, engineering design parameters, and limitations of the Chinese Fusion Engineering Test Reactor (CFETR). Based on the CFETR discharge simulation, magnetic measurement data are employed to reconstruct consistent plasma equilibrium parameters, and magnetic diagnostics’ number and position are optimized by truncated Singular value decomposition, verifying the redundancy reliability of the magnetic diagnostics layout design. This provides a design solution for the layout of the magnetic diagnostics system required to control the plasma equilibrium of CFETR, and the developed design and optimization method can provide effective support to design magnetic diagnostics systems for future magnetic confinement fusion devices.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"25 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140312185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anomalous spin Josephson effect in spin superconductors","authors":"Wen Zeng, Rui Shen","doi":"10.1088/1674-1056/ad1982","DOIUrl":"https://doi.org/10.1088/1674-1056/ad1982","url":null,"abstract":"The spin superconductor state is the spin-polarized triplet exciton condensate, which can be viewed as a counterpart of the charge superconductor state. As an analogy of the charge Josephson effect, the spin Josephson effect can be generated in the spin superconductor/normal metal/spin superconductor junctions. Here we study the spin supercurrent in the Josephson junctions consisting of two spin superconductors with noncollinear spin polarizations. For the Josephson junctions with out-of-plane spin polarizations, the possible <italic toggle=\"yes\">π</italic>-state spin supercurrent appears due to the Fermi momentum-splitting Andreev-like reflections at the normal metal/spin superconductor interfaces. For the Josephson junctions with in-plane spin polarizations, the anomalous spin supercurrent appears and is driven by the misorientation angle of the in-plane polarizations. The symmetry analysis shows that the appearance of the anomalous spin Josephson current is possible when the combined symmetry of the spin rotation and the time reversal is broken.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"58 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140006777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}