Frontiers of Physics最新文献

{"title":"Single-photon source with sub-MHz linewidth for cesium-based quantum information processing","authors":"Hai He,&nbsp;Peng-Fei Yang,&nbsp;Peng-Fei Zhang,&nbsp;Gang Li,&nbsp;Tian-Cai Zhang","doi":"10.1007/s11467-023-1317-z","DOIUrl":"10.1007/s11467-023-1317-z","url":null,"abstract":"<div><p>A single-photon source with narrow bandwidth, high purity, and large brightness can efficiently interact with material qubits strongly coupled to an optical microcavity for quantum information processing. Here, we experimentally demonstrate a degenerate doubly resonant single-photon source at 852 nm by the cavity-enhanced spontaneous parametric down-conversion process with a 100% duty cycle of generation. The single photon source possesses both high purity with a second-order correlation <i>g</i><span>\u0000 ⁽²⁾_<i>h</i>\u0000 \u0000 </span> (0) = 0.021 and narrow linewidth with Δ<i>ν</i>_<i>sp</i> = (800 ± 13) kHz. The single-photon source is compatible with the cesium atom D2 line and can be used for cesium-based quantum information processing.\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":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4498615","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":"The factorization-assisted topological-amplitude approach and its applications","authors":"Qin Qin,&nbsp;Chao Wang,&nbsp;Di Wang,&nbsp;Si-Hong Zhou","doi":"10.1007/s11467-023-1321-3","DOIUrl":"10.1007/s11467-023-1321-3","url":null,"abstract":"<div><p>Heavy meson decays provide an important platform for studies of both QCD and electroweak dynamics, which may contain some portals to understanding of nonperturbative QCD and physics beyond the Standard Model. The factorization-assisted topological-amplitude approach was proposed to study two-body non-leptonic <i>D</i> meson decays, where a promising QCD inspired approach from first principles is still missing. It was also applied to <i>B</i> meson decays whose subleading power contributions are difficult to calculate. By factorizing topological amplitudes into short distance Wilson coefficients and long distance hadronic matrix elements either to be calculated or to be parameterized, it provides an effective framework to extract information of nonperturbative dynamics involved. With important flavor <i>SU</i>(3) breaking effects taken into account, the data of the decay branching ratios (and also <i>CP</i> asymmetries in <i>B</i> decays) can be fitted well. The extracted amplitudes were further applied to make predictions for other observables, such as <i>CP</i> asymmetries in <i>D</i> decays, mixing parameters in the <span>({D^0} - {{bar D}^0})</span> system. By this review, we will describe the formulation of the factorization-assisted topological-amplitude approach and summarize its applications in <i>D</i> and <i>B</i> meson decays and highlight some of its achievements.\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":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4499990","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":"On the question of quark confinement in the Abelian U(1) QED gauge interaction","authors":"Cheuk-Yin Wong","doi":"10.1007/s11467-023-1288-0","DOIUrl":"10.1007/s11467-023-1288-0","url":null,"abstract":"<div><p>If we approximate light quarks as massless and apply the Schwinger confinement mechanism to light quarks, we will reach the conclusion that a light quark <i>q</i> and its antiquark <span>({bar q})</span> will be confined as a <span>(qbar q)</span> boson in the Abelian <i>U</i>(1) QED gauge interaction in (1+1)D, as in an open string. From the work of Coleman, Jackiw, and Susskind, we can infer further that the Schwinger confinement mechanism persists even for massive quarks in (1+ 1)D. Could such a QED-confined <span>(qbar q)</span> one-dimensional open string in (1 + 1) D be the idealization of a flux tube in the physical world in (3+l)D, similar to the case of QCD-confined <span>(qbar q)</span> open string? If so, the QED-confined <span>(qbar q)</span> bosons may show up as neutral QED mesons in the mass region of many tens of MeV [<i>Phys. Rev. C</i> 81, 064903 (2010) &amp; <i>J. High Energy Phys.</i> 2020(8), 165 (2020)]. Is it ever possible that a quark and an antiquark be produced and interact in QED alone to form a confined QED meson? Is there any experimental evidence for the existence of a QED meson (or QED mesons)? The observations of the anomalous soft photons, the XI7 particle, and the E38 particle suggest that they may bear the experimental evidence for the existence of such QED mesons. Further confirmation and investigations on the XI7 and E38 particles will shed definitive light on the question of quark confinement in QED in (3+1)D. Implications of quark confinement in the QED interaction are discussed.\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":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4499958","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":"Realization of highly isolated stable few-spin systems based on alkaline-earth fermions","authors":"Wen-Wei Wang,&nbsp;Han Zhang,&nbsp;Chang Qiao,&nbsp;Ming-Cheng Liang,&nbsp;Rui Wu,&nbsp;Xibo Zhang","doi":"10.1007/s11467-023-1314-2","DOIUrl":"10.1007/s11467-023-1314-2","url":null,"abstract":"<div><p>Few-level systems consisting of a certain number of spin states have provided the basis of a wide range of cold atom researches. However, more developments are still needed for better preparation of isolated few-spin systems. In this work, we demonstrate a highly nonlinear spin-discriminating (HNSD) method for isolating an arbitrary few-level manifold out of a larger total number of spin ground states in fermionic alkaline-earth atoms. With this method, we realize large and tunable energy shifts for unwanted spin states while inducing negligible shifts for the spin states of interest, which leads to a highly isolated few-spin system under minimal perturbation. Furthermore, the isolated few-spin system exhibits a long lifetime on the hundred-millisecond scale. Using the HNSD method, we demonstrate a characteristic Rabi oscillation between the two states of an isolated two-spin Fermi gas. Our method has wide applicability for realizing long-lived two-spin or high-spin quantum systems based on alkaline-earth fermions.\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":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4495383","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":"Reconfigurable memristor based on SrTiO3 thin-film for neuromorphic computing","authors":"Xiaobing Yan,&nbsp;Xu Han,&nbsp;Ziliang Fang,&nbsp;Zhen Zhao,&nbsp;Zixuan Zhang,&nbsp;Jiameng Sun,&nbsp;Yiduo Shao,&nbsp;Yinxing Zhang,&nbsp;Lulu Wang,&nbsp;Shiqing Sun,&nbsp;Zhenqiang Guo,&nbsp;Xiaotong Jia,&nbsp;Yupeng Zhang,&nbsp;Zhiyuan Guan,&nbsp;Tuo Shi","doi":"10.1007/s11467-023-1308-0","DOIUrl":"10.1007/s11467-023-1308-0","url":null,"abstract":"<div><p>Neuromorphic computing aims to achieve artificial intelligence by mimicking the mechanisms of biological neurons and synapses that make up the human brain. However, the possibility of using one reconfigurable memristor as both artificial neuron and synapse still requires intensive research in detail. In this work, Ag/SrTiO₃(STO)/Pt memristor with low operating voltage is manufactured and reconfigurable as both neuron and synapse for neuromorphic computing chip. By modulating the compliance current, two types of resistance switching, volatile and nonvolatile, can be obtained in amorphous STO thin film. This is attributed to the manipulation of the Ag conductive filament. Furthermore, through regulating electrical pulses and designing bionic circuits, the neuronal functions of leaky integrate and fire, as well as synaptic biomimicry with spike-timing-dependent plasticity and paired-pulse facilitation neural regulation, are successfully realized. This study shows that the reconfigurable devices based on STO thin film are promising for the application of neuromorphic computing 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":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4459639","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":"Topological non-Hermitian skin effect","authors":"Rijia Lin,&nbsp;Tommy Tai,&nbsp;Linhu Li,&nbsp;Ching Hua Lee","doi":"10.1007/s11467-023-1309-z","DOIUrl":"10.1007/s11467-023-1309-z","url":null,"abstract":"<div><p>This article reviews recent developments in the non-Hermitian skin effect (NHSE), particularly on its rich interplay with topology. The review starts off with a pedagogical introduction on the modified bulk-boundary correspondence, the synergy and hybridization of NHSE and band topology in higher dimensions, as well as, the associated topology on the complex energy plane such as spectral winding topology and spectral graph topology. Following which, emerging topics are introduced such as non-Hermitian criticality, dynamical NHSE phenomena, and the manifestation of NHSE beyond the traditional linear non-interacting crystal lattices, particularly its interplay with quantum many-body interactions. Finally, we survey the recent demonstrations and experimental proposals of NHSE.\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 5","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11467-023-1309-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4125171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An innovative approach based on meta-learning for real-time modal fault diagnosis with small sample learning","authors":"Tongfei Lei, Jiabei Hu, Saleem Riaz","doi":"10.3389/fphy.2023.1207381","DOIUrl":"https://doi.org/10.3389/fphy.2023.1207381","url":null,"abstract":"The actual multimodal process data usually exhibit non-linear time correlation and non-Gaussian distribution accompanied by new modes. Existing fault diagnosis methods have difficulty adapting to the complex nature of new modalities and are unable to train models based on small samples. Therefore, this paper proposes a new modal fault diagnosis method based on meta-learning (ML) and neural architecture search (NAS), MetaNAS. Specifically, the best performing network model of the existing modal is first automatically obtained using NAS, and then, the fault diagnosis model design is learned from the NAS of the existing model using ML. Finally, when generating new modalities, the gradient is updated based on the learned design experience, i.e., new modal fault diagnosis models are quickly generated under small sample conditions. The effectiveness and feasibility of the proposed method are fully verified by the numerical system and simulation experiments of the Tennessee Eastman (TE) chemical process. As a primary goal, the abstract should render the general significance and conceptual advance of the work clearly accessible to a broad readership. References should not be cited in the abstract. Leave the Abstract empty if your article does not require one–please see the “Article types” on every Frontiers journal page for full details.","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":" ","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43250620","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":"New symmetry reduction method for (1+1)-dimensional differential-difference equations","authors":"Jielin Lyu, Kaizhong Shi, Bo Ren, Yongyang Jin","doi":"10.3389/fphy.2023.1237805","DOIUrl":"https://doi.org/10.3389/fphy.2023.1237805","url":null,"abstract":"We propose a new symmetry reduction method for (1+1)-dimensional differential-difference equations (DDEs), namely, the λ-symmetry reduction method of solving ordinary differential equations is generalized to DDEs. Order-reduction processes are a consequence of the invariance of the given DDE under vector fields of the new class. These vector fields satisfy a new prolongation formula. A simple example of order-reduction is provided to illustrate the application.","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":" ","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44380024","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":"Cost-sensitive classification algorithm combining the Bayesian algorithm and quantum decision tree","authors":"Naihua Ji, Rongyi Bao, Xiaoyi Mu, Zhao Chen, Xin Yang, Shumei Wang","doi":"10.3389/fphy.2023.1179868","DOIUrl":"https://doi.org/10.3389/fphy.2023.1179868","url":null,"abstract":"This study highlights the drawbacks of current quantum classifiers that limit their efficiency and data processing capabilities in big data environments. The paper proposes a global decision tree paradigm to address these issues, focusing on designing a complete quantum decision tree classification algorithm that is accurate and efficient while also considering classification costs. The proposed method integrates the Bayesian algorithm and the quantum decision tree classification algorithm to handle incremental data. The proposed approach generates a suitable decision tree dynamically based on data objects and cost constraints. To handle incremental data, the Bayesian algorithm and quantum decision tree classification algorithm are integrated, and kernel functions obtained from quantum kernel estimation are added to a linear quantum support vector machine to construct a decision tree classifier using decision directed acyclic networks of quantum support vector machine nodes (QKE). The experimental findings demonstrate the effectiveness and adaptability of the suggested quantum classification technique. In terms of classification accuracy, speed, and practical application impact, the proposed classification approach outperforms the competition, with an accuracy difference from conventional classification algorithms being less than 1%. With improved accuracy and reduced expense as the incremental data increases, the efficiency of the suggested algorithm for incremental data classification is comparable to previous quantum classification algorithms. The proposed global decision tree paradigm addresses the critical issues that need to be resolved by quantum classification methods, such as the inability to process incremental data and the failure to take the cost of categorization into account. By integrating the Bayesian algorithm and the quantum decision tree classification algorithm and using QKE, the proposed method achieves high accuracy and efficiency while maintaining high performance when processing incremental sequences and considering classification costs. Overall, the theoretical and experimental findings demonstrate the effectiveness of the suggested quantum classification technique, which offers a promising solution for handling big data classification tasks that require high accuracy and efficiency.","PeriodicalId":573,"journal":{"name":"Frontiers of Physics","volume":" ","pages":""},"PeriodicalIF":7.5,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44780951","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":"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}