Frontiers of Physics最新文献

{"title":"Quantum simulation of Hofstadter butterfly with synthetic gauge fields on two-dimensional superconducting-qubit lattices","authors":"Wei Feng,&nbsp;Dexi Shao,&nbsp;Guo-Qiang Zhang,&nbsp;Qi-Ping Su,&nbsp;Jun-Xiang Zhang,&nbsp;Chui-Ping Yang","doi":"10.1007/s11467-023-1319-x","DOIUrl":"10.1007/s11467-023-1319-x","url":null,"abstract":"<div><p>Motivated by recent realizations of two-dimensional (2D) superconducting-qubit lattices, we propose a protocol to simulate Hofstadter butterfly with synthetic gauge fields in superconducting circuits. Based on the existing 2D superconducting-qubit lattices, we construct a generalized Hofstadter model on zigzag lattices, which has a fractal energy spectrum similar to the original Hofstadter butterfly. By periodically modulating the resonant frequencies of qubits, we engineer a synthetic gauge field to mimic the generalized Hofstadter Hamiltonian. A spectroscopic method is used to demonstrate the Hofstadter butterfly from the time evolutions of experimental observables. We numerically simulate the dynamics of the system with realistic parameters, and the results show a butterfly spectrum clearly. Our proposal provides a promising way to realize the Hofstadter butterfly on the latest 2D superconducting-qubit lattices and will stimulate the quantum simulation of novel properties induced by magnetic fields in superconducting circuits.\u0000</p><figure><div><div><div><picture><source><img></source></picture></div></div></div></figure></div>","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":"18 6","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4031996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Preparing quantum states by measurement-feedback control with Bayesian optimization","authors":"Yadong Wu,&nbsp;Juan Yao,&nbsp;Pengfei Zhang","doi":"10.1007/s11467-023-1311-5","DOIUrl":"10.1007/s11467-023-1311-5","url":null,"abstract":"<div><p>The preparation of quantum states is crucial for enabling quantum computations and simulations. In this work, we present a general framework for preparing ground states of many-body systems by combining the measurement-feedback control process (MFCP) with machine learning techniques. Specifically, we employ Bayesian optimization (BO) to enhance the efficiency of determining the measurement and feedback operators within the MFCP. As an illustration, we study the ground state preparation of the one-dimensional Bose–Hubbard model. Through BO, we are able to identify optimal parameters that can effectively drive the system towards low-energy states with a high probability across various quantum trajectories. Our results open up new directions for further exploration and development of advanced control strategies for quantum computations and simulations.</p></div>","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":"18 6","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4030628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Athlete injury detection and emergency treatment in mobile smart medical system","authors":"Yiqiao Zhang, Qian Zhang, Yuhe Liu","doi":"10.3389/fphy.2023.1191485","DOIUrl":"https://doi.org/10.3389/fphy.2023.1191485","url":null,"abstract":"Using the sports injury monitoring system to detect injury symptoms in time and take effective treatment measures in time can reduce the damage caused by sports injuries to athletes. However, many current detection methods lack the support of advanced technologies and algorithms, resulting in poor performance in sports injury detection. Based on this, a mobile intelligent medical system is designed in this paper, and an athlete injury detection method based on CNN and sensors is proposed. The method includes three parts: motion region acquisition, motion injury feature extraction, and motion injury detection. In addition, for emergency treatment, this paper proposes a variety of CNN-based image data analysis methods to ensure the accuracy of the processing process. The experimental results show that the athlete injury detection method based on the convolutional neural network improves the detection accuracy by 6.73% compared with the traditional method, which also provides an important reference for the future application of ML in medical treatment. The research confirms that the construction and analysis of mobile intelligent medical system can effectively improve the accuracy of sports injury detection.","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":" ","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41700452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Editorial: Moving boundary problems in multi-physics coupling processes","authors":"Pei Li, Leilei Chen, E. Atroshchenko","doi":"10.3389/fphy.2023.1219806","DOIUrl":"https://doi.org/10.3389/fphy.2023.1219806","url":null,"abstract":"In many problems such as propagation of crack, fluid-structure interaction, flow in deformable porous materials, material forming process and so on, the boundary of material/ structure or the interface between different materials/structures varies depending on the insitu responses of associating components and environmental factors. Such problems are also named as moving boundary problems, and the time-dependent boundary poses significant challenges to the numerical modelling of such problems as well as the study of inherent mechanisms dominating the evolution of moving boundaries. Severe nonlinearity caused by the moving boundary requires development of advanced numerical algorithms, while interaction of multi-physics behaviors in moving boundary problems such as mechanical, thermal, electrical and even chemical response, necessitates research of multi-physical modelling methodologies. This Research Topic “Moving Boundary Problems in Multi-physics Coupling Processes” collects 16 papers contributing to the experimental, numerical and theoretical research on moving boundary problems of multi-physics processes. While focusing on “Moving Boundary Problems in Multi-physics Coupling Processes,” the selected papers show a good diversity in terms of their research objects, methods and findings. Some contributors have obtained valuable achievements on modelling of cracks. For instance, Ma et al. used discrete element method to establish a numerical model of porous concrete with random circular defects inside, to study the influence of the porosity or size homogeneity of the defects on the mechanical behavior, crack evolution, and acoustic emission (AE) responses. Their findings can aim the understanding of micro-scale mechanism of crack propagation in porous concrete. To accelerate the numerical simulations of fracture, Liu et al. employed degradation function that decouples the phase-field and physical length scales, to reduce the mesh density in large structures. By incorporating the Drucker-Prager failure surface into the phase field model to characterize the tension-compression asymmetry of fractures in rocks, they can capture the crack propagation path in rock materials with a good accuracy and efficiency. Instead of using conventional numerical methods, Lian et al. proposed a novel framework for efficient simulation of crack propagation in brittle materials, whereby the partial differential OPEN ACCESS","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":" ","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41913813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Mitigating transverse mode instability in fiber laser oscillator by employing direct pump modulation","authors":"Junyu Chai, Wenguang Liu, Xiao-lin Wang, Qiong Zhou, Jiangbin Zhang, Peng Liu, Hanwei Zhang, Yao Lu, Dan Zhang, Zong-fu Jiang, Guo-min Zhao","doi":"10.3389/fphy.2023.1212811","DOIUrl":"https://doi.org/10.3389/fphy.2023.1212811","url":null,"abstract":"The transverse mode instability (TMI) is a thermal-optical effect, inducing a sudden deterioration of beam quality and average power. This non-linear effect will greatly limit the power scaling of fiber lasers. We demonstrate a direct pump modulation to mitigate TMI in a 30 μm-core-diameter all-fiber laser oscillator. It only relies on function generator and pump drivers without the need of feedback control units. The groups of pump LDs and pump drivers and the phase difference between the channels of function generator have a great impact on the beam stability. Compared with the TMI threshold 180 W in continuous wave (CW) mode, the maximum average output power of a stabilized beam is increased up to 310 W via a multi-parameter-based direct pump modulation.","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":" ","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45091302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Freeze-drying assisted liquid exfoliation of BiFeO3 for pressure sensing","authors":"Yuping Li,&nbsp;Mengwei Dong,&nbsp;Xuejie Zou,&nbsp;Jinhao Zhang,&nbsp;Jian Zhang,&nbsp;Xiao Huang","doi":"10.1007/s11467-023-1301-7","DOIUrl":"10.1007/s11467-023-1301-7","url":null,"abstract":"<div><p>Breaking up bulk crystals of functional materials into nanoscale thinner layers can lead to interesting properties and enhanced functionalities due to the size and interface effects. However, unlike the van der Waals layered crystals, many materials cannot be exfoliated into thin layers by liquid exfoliation. BiFeO₃ is a piezoelectric ceramic material, which is commonly synthesized as bulk crystals, limiting its wider applications. In this contribution, a freeze-drying assisted liquid exfoliation method was adopted to fabricate thin-layered BiFeO₃ nanoplates with lateral sizes of up to 500 nm and thicknesses of 10–20 nm. The freeze-drying process showed a vital role in the preparation process by imposing stress on the dispersed BiFeO₃ crystals during the liquid-to-solid-to-gas transition of the solvent. Such stress resulted in lattice strains in the freeze-dried BiFeO₃ crystals, which enabled their further exfoliation under subsequent ultrasonication. Considering the intrinsic piezoelectric effect of BiFeO₃, pressure sensors based on bulk and thin-layer BiFeO₃ were also fabricated. The pressure sensor based on BiFeO₃ nanoplates exhibited a largely enhanced sensitivity with a wider working range than the bulk counterpart, because of the stronger piezoelectric effect induced and the extra electrical charges at abundant interlayer interfaces. We suggest that the freeze-drying assisted liquid exfoliation method can be applied to other non-van der Waals crystals to bring about more functional material systems.\u0000</p><figure><div><div><div><picture><source><img></source></picture></div></div></div></figure></div>","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":"18 6","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5623762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Alloy-induced reduction and anisotropy change of lattice thermal conductivity in Ruddlesden–Popper phase halide perovskites","authors":"Huimin Mu,&nbsp;Kun Zhou,&nbsp;Fuyu Tian,&nbsp;Yansong Zhou,&nbsp;Guoqi Zhao,&nbsp;Yuhao Fu,&nbsp;Lijun Zhang","doi":"10.1007/s11467-023-1315-1","DOIUrl":"10.1007/s11467-023-1315-1","url":null,"abstract":"<div><p>The effective modulation of the thermal conductivity of halide perovskites is of great importance in optimizing their optoelectronic device performance. Based on first-principles lattice dynamics calculations, we found that alloying at the B and X sites can significantly modulate the thermal transport properties of 2D Ruddlesden–Popper (RP) phase halide perovskites, achieving a range of lattice thermal conductivity values from the lowest (<i>κ</i>_<i>c</i> = 0.05 W·m⁻¹·K⁻¹@Cs₄AgBiI₈) to the highest (<i>κ</i>_<i>a/b</i> = 0.95 W·m⁻¹·K⁻¹@Cs₄NaBiCl₄I₄). Compared with the pure RP-phase halide perovskites and three-dimensional halide perovskite alloys, the two-dimensional halide perovskite introduces more phonon branches through alloying, resulting in stronger phonon branch coupling, which effectively scatters phonons and reduces thermal conductivity. Alloying can also dramatically regulate the thermal transport anisotropy of RP-phase halide perovskites, with the anisotropy ratio ranging from 1.22 to 4.13. Subsequently, analysis of the phonon transport modes in these structures revealed that the lower phonon velocity and shorter phonon lifetime were the main reasons for their low thermal conductivity. This work further reduces the lattice thermal conductivity of 2D pure RP-phase halide perovskites by alloying methods and provides a strong support for theoretical guidance by gaining insight into the interesting phonon transport phenomena in these compounds.\u0000</p><figure><div><div><div><picture><source><img></source></picture></div></div></div></figure></div>","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":"18 6","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5623755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Impact of institutional organization on research productivity and multidisciplinarity","authors":"A. García‐Rodríguez, R. Barrio, T. Govezensky, J. Tagüeña, Miguel Robles Pérez, H. C. Calvet, José Luis, Jiménez Andrade, R. Arencibia-Jorge, K. Kaski, Jiang Zhu, Jordi Duch Gavalda","doi":"10.3389/fphy.2023.1161019","DOIUrl":"https://doi.org/10.3389/fphy.2023.1161019","url":null,"abstract":"In this article, we will describe a model to examine the influence of differently organized institutions on their scientific productivity. We take two extreme cases, on one hand, an institution divided in departments with no collaboration between people in different departments. These could be disciplines or merely projects. On the other hand, we consider an institution that allows interactions between all individuals, without a departmental structure to a department. We compare the results with data from the Institute of Renewable Energy (IER) at UNAM, which has changed its organization and policies during the last 30 years, and we could quantitatively predict the changes observed in productivity and multidisciplinarity. This model can be applied to a broader set of institutions and processes.","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":" ","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47517245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Convolutional neural network classification of ultrasound images by liver fibrosis stages based on echo-envelope statistics","authors":"S. Hirata, Akiho Isshiki, D. Tai, P. Tsui, Kenji Yoshida, Tadashi Yamaguchi","doi":"10.3389/fphy.2023.1164622","DOIUrl":"https://doi.org/10.3389/fphy.2023.1164622","url":null,"abstract":"Introduction: Assessing the stage of liver fibrosis during the diagnosis and follow-up of patients with diffuse liver disease is crucial. The tissue structure in the fibrotic liver is reflected in the texture and contrast of an ultrasound image, with the pixel brightness indicating the intensity of the echo envelope. Therefore, the progression of liver fibrosis can be evaluated non-invasively by analyzing ultrasound images. Methods: A convolutional-neural-network (CNN) classification of ultrasound images was applied to estimate liver fibrosis. In this study, the colorization of the ultrasound images using echo-envelope statistics that correspond to the features of the images is proposed to improve the accuracy of CNN classification. In the proposed method, the ultrasound image is modulated by the 3rd- and 4th-order moments of pixel brightness. The two modulated images and the original image were then synthesized into a color image of RGB representation. Results and Discussion: The colorized ultrasound images were classified via transfer learning of VGG-16 to evaluate the effect of colorization. Of the 80 ultrasound images with liver fibrosis stages F1–F4, 38 images were accurately classified by the CNN using the original ultrasound images, whereas 47 images were classified by the proposed method.","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":" ","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41805391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Development of an APPLE III undulator prototype with three-dimensional force compensation for SHINE","authors":"Chenglong Yu, Ya Zhu, Wei Zhang, Jie Yang, Yongzhou He, Tingting Zhen, Tao Liu, Yangyang Lei, Q. Yuan, D. Yuan, Yongmei Wen, R. Deng, Zhiqiang Jiang, H. Deng, Bo Liu, Dong Wang","doi":"10.3389/fphy.2023.1174620","DOIUrl":"https://doi.org/10.3389/fphy.2023.1174620","url":null,"abstract":"The Shanghai high-repetition-rate XFEL and extreme light facility (SHINE) plans to install several elliptically polarizing undulators (EPUs) as afterburners behind the planar undulator section to obtain nearly saturated circularly polarized free-electron laser (FEL) radiation. Therefore, the SHINE R&D project needs to develop a 4-m-long EPU with an effective magnetic field of 1.5 T, a period of 68 mm, and a minimum gap of 3 mm. A magnetic force compensation EPU prototype has recently been built and tested at the Shanghai Synchrotron Radiation Facility (SSRF) based on the addition of permanent magnets. This prototype can realize magnetic compensation under various polarization modes in all working gaps, thereby reducing the deformation of the girders and maintaining sufficient rigidity of the mechanical structure. A girder deformation monitoring system was established to obtain real force compensation feedback. The final magnetic field measurement results meet the physical requirements, and the proposed scheme can be used as an alternative to the EPU with a high magnetic field and large magnetic force.","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":" ","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42733725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}