Hasil untuk "Periodicals"

T. Kitagawa, E. Berg, M. Rudner et al.

Topological properties of physical systems can lead to robust behaviors that are insensitive to microscopic details. Such topologically robust phenomena are not limited to static systems but can also appear in driven quantum systems. In this paper, we show that the Floquet operators of periodically driven systems can be divided into topologically distinct (homotopy) classes, and give a simple physical interpretation of this classification in terms of the spectra of Floquet operators. Using this picture, we provide an intuitive understanding of the well-known phenomenon of quantized adiabatic pumping. Systems whose Floquet operators belong to the trivial class simulate the dynamics generated by time-independent Hamiltonians, which can be topologically classified according to the schemes developed for static systems. We demonstrate these principles through an example of a periodically driven two--dimensional hexagonal lattice model which exhibits several topological phases. Remarkably, one of these phases supports chiral edge modes even though the bulk is topologically trivial.

L. Myers, R. Eckardt, M. Fejer et al.

R. Rudell

Yennun Huang, C. Kintala, N. Kolettis et al.

Z. Xia, Yunfa Zhang, F. Ellyin

Mao Ye, Chengfa Li, Guihai Chen et al.

Charles Nelson, Chang-Jin Kim

E. Genersch, W. Ohe, H. Kaatz et al.

Yi Wang, Rong Yang, Zhiwen Shi et al.

P. de Maayer, D. Anderson, C. Cary et al.

T. Crough, R. Khanna

Chengfa Li, Mao Ye, Guihai Chen et al.

Sebabrata Mukherjee, A. Spracklen, M. Valiente et al.

Topological quantum matter can be realized by subjecting engineered systems to time-periodic modulations. In analogy with static systems, periodically driven quantum matter can be topologically classified by topological invariants, whose non-zero value guarantees the presence of robust edge modes. In the high-frequency limit of the drive, topology is described by standard topological invariants, such as Chern numbers. Away from this limit, these topological numbers become irrelevant, and novel topological invariants must be introduced to capture topological edge transport. The corresponding edge modes were coined anomalous topological edge modes, to highlight their intriguing origin. Here we demonstrate the experimental observation of these topological edge modes in a 2D photonic lattice, where these propagating edge states are shown to coexist with a quasi-localized bulk. Our work opens an exciting route for the exploration of topological physics in time-modulated systems operating away from the high-frequency regime. A periodically driven system may show a novel type of topologically protected edge modes that has no static analogue. Here, Mukherjeeet al. report the observation of such anomalous chiral edge modes in an ultrafast-laser-inscribed slowly-driven photonic lattice.

Jie Zhao, Chaoxuan Ma, M. Ruesing et al.

A thin-film periodically poled lithium niobate waveguide was designed and fabricated which generates entangled photon pairs at telecommunications wavelengths with high coincidences-to-accidentals counts ratio CAR>67000, two-photon interference visibility V>99%, and heralded single-photon autocorrelation g_{H}^{(2)}(0)<0.025. Nondestructive in situ diagnostics were used to determine the poling quality in 3D. Megahertz rates of photon pairs were generated by less than a milliwatt of pump power, simplifying the pump requirements and dissipation compared to traditional spontaneous parametric down-conversion lithium niobate devices.

Tomotaka Kuwahara, Takashi Mori, Keiji Saito

This work explores a fundamental dynamical structure for a wide range of many-body quantum systems under periodic driving. Generically, in the thermodynamic limit, such systems are known to heat up to infinite temperature states after infinite-time evolution, irrespective of dynamical details. In the present study, instead of considering infinitely long-time scale, we aim to provide a framework to understand the long but finite time behavior, namely the transient dynamics. In the analysis, we focus on the Floquet-Magnus (FM) expansion that gives a formal expression of the effective Hamiltonian on the system. Although in general the full series expansion is not convergent in the thermodynamics limit, we give a clear relationship between the FM expansion and the transient dynamics. More precisely, we rigorously show that a truncated version of the FM expansion accurately describes the exact dynamics for a finite-time scale. Our result reveals a reliable time scale of the validity of the FM expansion, which can be comparable to the experimental time scale. Furthermore, we discuss several dynamical phenomena, such as the effect of small integrability breaking, efficient numerical simulation of periodically driven systems, dynamical localization and thermalization. Especially on thermalization, we discuss generic scenario of the prethermalization phenomenon in periodically driven systems.

Xiaoming Shi, Heng Qi, Yanming Shen et al.

Accurate traffic forecasting is important to enable intelligent transportation systems in a smart city. This problem is challenging due to the complicated spatial, short-term temporal and long-term periodical dependencies. Existing approaches have considered these factors in modeling. Most solutions apply CNN, or its extension Graph Convolution Networks (GCN) to model the spatial correlation. However, the convolution operator may not adequately model the non-Euclidean pair-wise correlations. In this paper, we propose a novel Attention-based Periodic-Temporal neural Network (APTN), an end-to-end solution for traffic foresting that captures spatial, short-term, and long-term periodical dependencies. APTN first uses an encoder attention mechanism to model both the spatial and periodical dependencies. Our model can capture these dependencies more easily because every node attends to all other nodes in the network, which brings regularization effect to the model and avoids overfitting between nodes. Then, a temporal attention is applied to select relevant encoder hidden states across all time steps. We evaluate our proposed model using real world traffic datasets and observe consistent improvements over state-of-the-art baselines.

Jian-Qiao Fang, Zhiyuan Bian, Yongyuan Lu et al.

Introduction Postoperative pain is common after surgery, with a high incidence and risk of becoming chronic. Current multimodal analgesia has drawbacks, including limited efficacy from single agents and opioid side effects and addiction risk. These issues have led to opioid-sparing multimodal analgesia. Transcutaneous auricular vagus nerve stimulation (taVNS) is non-invasive and convenient. Studies have shown it can reduce postoperative pain, improve mood and lower adverse events. However, taVNS lacks a comprehensive evaluation and standardised protocols, so further research is needed to provide reliable evidence.Methods and analysis This study strictly adheres to the guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. To identify suitable randomised controlled trials (RCTs), eight credible databases will be searched, including four English databases (Web of Science, PubMed, Cochrane Central Register of Controlled Trials, EMBASE) and four Chinese databases (China National Knowledge Infrastructure, VIP Database for Chinese Technical Periodicals, Wanfang Database, Chinese Biomedical Literature Database). RevMan V.5.3 will be employed to integrate the retrieved data and conduct meta-analyses. The methodological quality of included RCTs will be evaluated using the Cochrane Risk of Bias Assessment 2.0 tool. Additionally, the Grading of Recommendations, Assessment, Development and Evaluation system will be applied to assess the strength and certainty of the evidence. We will also conduct publication bias analyses, sensitivity analyses and subgroup analyses.Ethics and dissemination No ethical review is required as no private or confidential patient data will be included. Results of this study will be disseminated through a peer-reviewed journal.PROSPERO registration number CRD420251207651.

Dmitry D. Nikolaev

The article analyzes the publications in Russian periodicals in 1910, which appeared in connection with Mark Twain’s death. Some of them are anonymous or signed with undisclosed pseudonyms, others are written by famous writers (A.T. Averchenko, N.E. Heinze, P.T. Gerzo-Vinogradsky, V.M. Doroshevich, A.A. Izmailov, A.I. Kuprin, P.A. Tversky, K.I. Chukovsky). The reaction to Twain’s death showed that he was the most famous American writer in Russia and emphasized his importance to the Russian audience. For the authors of the obituaries his death was a personal loss. The list of writers in which Twain was placed (Swift, Dickens, Gogol, Saltykov-Shchedrin, Chekhov) reflects the scale of his genius, as well as the fact that a humorist also can be recognized as a great writer. The analysis of periodicals also helps to draw conclusions about the age related, social, ideological and aesthetic aspects of Twain’s reception in Russia. Special attention is paid to “americanism” which Twain embodies in literature and in life for a significant part of the readers. The similarity of critical evaluations, emotions, examples taken from Twain’s works, jokes and biographical details proves the existence of a definite Russian image of Twain, as well as certain clichés in reception of Twain’s work and American literature in general.

Qiangzhong Wang, Jinqiang Li, Zhang Yao et al.

Abstract In this study, a novel plate-type resonator is proposed, and the bandgap properties of a metamaterial sandwich plate containing a two-dimensional periodic array of these plate-type resonators are numerically and experimentally investigated. The finite element method is applied to calculate the band structure and the transmission spectra. The formation mechanisms of the bandgaps are investigated via the analysis of the mode shapes of the plate-type resonator and face plate in a unit cell. The results demonstrate that both locally resonant and Bragg bandgaps exist in the proposed structure. The selective coupling between the resonant modes of the plate-type resonator and the face plate is a necessary condition for the generation of locally resonant bandgaps that the resonant modes of the plate-type resonator can produce a reaction force on the support. The effect of the geometric parameters and surface mass ratio on the bandgaps is investigated, and the effect of the introduction of the plate-type resonator on the Bragg bandgap is studied. The improvements of the plate-type resonator by changing its structure or moving its attachment point are also discussed. Moreover, a metamaterial sandwich plate specimen is fabricated and vibration experiments are conducted, and it is observed that there is good agreement between the numerical predictions and the experimental results. The proposed strategy contributes to the possibility of fabricating a simpler structure to promote the exploitation of metamaterial sandwich plates in engineering.

P. Bordia, H. Lüschen, U. Schneider et al.

Periodically driven quantum many-body systems can display rich dynamics and host exotic phases that are absent in their undriven counterparts. However, in the presence of interactions such systems are expected to eventually heat up to a simple infinite-temperature state. One possible exception is a periodically driven many-body localized system, in which heating is precluded by strong disorder. Here, we use a gas of ultracold fermionic potassium atoms in optical lattices to prepare and probe such a driven system and show that it is indeed stable for high enough driving frequency. Moreover, we find a novel regime in which the system is exceedingly stable even at low drive frequencies, a particular feature of our driving scheme. Our experimental findings are well supported by numerical simulations and may provide avenues for engineering novel phases in periodically driven matter. Many-body localization, which exhibits a fascinating interplay between disorder and interactions, can be studied using ultracold atoms in a quasiperiodic chain. Adding periodic driving makes things even more interesting.