arXiv - PHYS - Disordered Systems and Neural Networks最新文献_第10页

Transmission across a ribbon containing a square PT impurity 在含有方形 PT 杂质的色带上的传输

arXiv - PHYS - Disordered Systems and Neural Networks Pub Date : 2024-03-20 DOI: arxiv-2403.13217

Cristian Mejía-Cortés, Mario I. Molina

引用次数: 0

Two-level systems and harmonic excitations in a mean-field anharmonic quantum glass 均场非谐波量子玻璃中的两级系统和谐波激发

arXiv - PHYS - Disordered Systems and Neural Networks Pub Date : 2024-03-19 DOI: arxiv-2403.12740

Thibaud Maimbourg

{"title":"Two-level systems and harmonic excitations in a mean-field anharmonic quantum glass","authors":"Thibaud Maimbourg","doi":"arxiv-2403.12740","DOIUrl":"https://doi.org/arxiv-2403.12740","url":null,"abstract":"Structural glasses display at low temperature a set of anomalies in\u0000thermodynamic observables. The prominent example is the linear-in-temperature\u0000scaling of the specific heat, at odds with the Debye cubic scaling found in\u0000crystals, due to acoustic phonons. Such an excess of specific heat in amorphous\u0000solids is thought of arising from phenomenological soft excitations dubbed\u0000tunneling two-level systems (TTLS). Their nature as well as their statistical\u0000properties remain elusive from a first-principle viewpoint. In this work we\u0000investigate the canonically quantized version of the KHGPS model, a mean-field\u0000glass model of coupled anharmonic oscillators, across its phase diagram, with\u0000an emphasis on the specific heat. The thermodynamics is solved in a\u0000semiclassical expansion. We show that in the replica-symmetric region of the\u0000model, up to the marginal glass transition line where replica symmetry gets\u0000continuously broken, a disordered version of the Debye approximation holds: the\u0000specific heat is dominated by harmonic vibrational excitations inducing a\u0000power-law scaling at the transition, ruled by random matrix theory. This\u0000mechanism generalizes a previous semiclassical argument in the literature. We\u0000then study the marginal glass phase where the semiclassical expansion becomes\u0000non-perturbative due to the emergence of instantons that overcome disordered\u0000Debye behavior. Inside the glass phase, a variational solution to the instanton\u0000approach provides the prevailing excitations as TTLS, which generate a linear\u0000specific heat. This phase thus hosts a mix of TTLS and harmonic excitations\u0000generated by interactions. We finally suggest to go beyond the variational\u0000approximation through an analogy with the spin-boson model.","PeriodicalId":501066,"journal":{"name":"arXiv - PHYS - Disordered Systems and Neural Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140168877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Inhomogeneous Floquet thermalization 非均质 Floquet 热化

arXiv - PHYS - Disordered Systems and Neural Networks Pub Date : 2024-03-13 DOI: arxiv-2403.08369

Soumya Bera, Ishita Modak, Roderich Moessner

引用次数: 0

Small field chaos in spin glasses: universal predictions from the ultrametric tree and comparison with numerical simulations 自旋玻璃中的小场混沌：超计量树的普遍预测以及与数值模拟的比较

arXiv - PHYS - Disordered Systems and Neural Networks Pub Date : 2024-03-13 DOI: arxiv-2403.08503

Miguel Aguilar-Janita, Silvio Franz, Victor Martin-Mayor, Javier Moreno-Gordo, Giorgio Parisi, Federico Ricci-Tersenghi, Juan J. Ruiz-Lorenzo

{"title":"Small field chaos in spin glasses: universal predictions from the ultrametric tree and comparison with numerical simulations","authors":"Miguel Aguilar-Janita, Silvio Franz, Victor Martin-Mayor, Javier Moreno-Gordo, Giorgio Parisi, Federico Ricci-Tersenghi, Juan J. Ruiz-Lorenzo","doi":"arxiv-2403.08503","DOIUrl":"https://doi.org/arxiv-2403.08503","url":null,"abstract":"We study the chaotic behavior of the Gibbs state of spin-glasses under the\u0000application of an external magnetic field, in the crossover region where the\u0000field intensity scales proportional to $1/sqrt{N}$, being $N$ the system size.\u0000We show that Replica Symmetry Breaking (RSB) theory provides universal\u0000predictions for chaotic behavior: they depend only on the zero-field overlap\u0000probability function $P(q)$ and are independent of other features of the\u0000system. Using solely $P(q)$ as input we can analytically predict quantitatively\u0000the statistics of the states in a small field. In the infinite volume limit,\u0000each spin-glass sample is characterized by an infinite number of states that\u0000have a tree-like structure. We generate the corresponding probability\u0000distribution through efficient sampling using a representation based on the\u0000Bolthausen-Snitmann coalescent. In this way, we can compute quantitatively\u0000properties in the presence of a magnetic field in the crossover region, the\u0000overlap probability distribution in the presence of a small field and the\u0000degree of decorrelation as the field is increased. To test our computations, we\u0000have simulated the Bethe lattice spin glass and the 4D Edwards-Anderson model,\u0000finding in both cases excellent agreement with the universal predictions.","PeriodicalId":501066,"journal":{"name":"arXiv - PHYS - Disordered Systems and Neural Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140124800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Spin model for global flat-foldability of random origami 随机折纸全局平面可折叠性的 Spin 模型

arXiv - PHYS - Disordered Systems and Neural Networks Pub Date : 2024-03-12 DOI: arxiv-2403.07306

Chihiro Nakajima

引用次数: 0

Effect of Ir growth pressure on the domain wall dynamics in Ta/Pt/Co/Ir/Ta stacks Ir 生长压力对 Ta/Pt/Co/Ir/Ta 叠层畴壁动力学的影响

arXiv - PHYS - Disordered Systems and Neural Networks Pub Date : 2024-03-11 DOI: arxiv-2403.07141

P. Domenichini, J. Brock, J. Curiale, A. B. Kolton

{"title":"Effect of Ir growth pressure on the domain wall dynamics in Ta/Pt/Co/Ir/Ta stacks","authors":"P. Domenichini, J. Brock, J. Curiale, A. B. Kolton","doi":"arxiv-2403.07141","DOIUrl":"https://doi.org/arxiv-2403.07141","url":null,"abstract":"The dynamical response of magnetic domain walls to external magnetic fields\u0000in ultra-thin multilayer magnetic films is determined not only by the\u0000composition and thickness of the layers but also by the growth conditions.\u0000Growth conditions can induce significant structural changes inside the layers\u0000and at the interfaces between them, affecting in particular the dynamics of\u0000domain walls, their mobility, elastic tension, and the pinning forces acting on\u0000them. In this work, we focus specifically on the effect of Ir layer growth\u0000pressure in Ta/Pt/Co/Ir/Ta ultra-thin multilayers films. Measurements of the DC\u0000magnetic properties, domain wall velocity and domain morphology in the creep\u0000regime for both constant and alternating field pulses, were performed for a\u0000batch of samples where the Ir layer was grown at different pressures. We find\u0000that the saturation magnetization, the effective anisotropy constant and the\u0000domain wall surface tension grow with increasing pressure and saturate at a\u0000threshold pressure, while the Dzyaloshinskii-Moriya field and the strength of\u0000the disorder remain practically unaltered over the range of pressures\u0000considered.","PeriodicalId":501066,"journal":{"name":"arXiv - PHYS - Disordered Systems and Neural Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140115956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Geometric Dynamics of Signal Propagation Predict Trainability of Transformers 信号传播的几何动力学预测变压器的可培训性

arXiv - PHYS - Disordered Systems and Neural Networks Pub Date : 2024-03-05 DOI: arxiv-2403.02579

Aditya Cowsik, Tamra Nebabu, Xiao-Liang Qi, Surya Ganguli

{"title":"Geometric Dynamics of Signal Propagation Predict Trainability of Transformers","authors":"Aditya Cowsik, Tamra Nebabu, Xiao-Liang Qi, Surya Ganguli","doi":"arxiv-2403.02579","DOIUrl":"https://doi.org/arxiv-2403.02579","url":null,"abstract":"We investigate forward signal propagation and gradient back propagation in\u0000deep, randomly initialized transformers, yielding simple necessary and\u0000sufficient conditions on initialization hyperparameters that ensure\u0000trainability of deep transformers. Our approach treats the evolution of the\u0000representations of $n$ tokens as they propagate through the transformer layers\u0000in terms of a discrete time dynamical system of $n$ interacting particles. We\u0000derive simple update equations for the evolving geometry of this particle\u0000system, starting from a permutation symmetric simplex. Our update equations\u0000show that without MLP layers, this system will collapse to a line, consistent\u0000with prior work on rank collapse in transformers. However, unlike prior work,\u0000our evolution equations can quantitatively track particle geometry in the\u0000additional presence of nonlinear MLP layers, and it reveals an order-chaos\u0000phase transition as a function of initialization hyperparameters, like the\u0000strength of attentional and MLP residual connections and weight variances. In\u0000the ordered phase the particles are attractive and collapse to a line, while in\u0000the chaotic phase the particles are repulsive and converge to a regular\u0000$n$-simplex. We analytically derive two Lyapunov exponents: an angle exponent\u0000that governs departures from the edge of chaos in this particle system, and a\u0000gradient exponent that governs the rate of exponential growth or decay of\u0000backpropagated gradients. We show through experiments that, remarkably, the\u0000final test loss at the end of training is well predicted just by these two\u0000exponents at the beginning of training, and that the simultaneous vanishing of\u0000these two exponents yields a simple necessary and sufficient condition to\u0000achieve minimal test loss.","PeriodicalId":501066,"journal":{"name":"arXiv - PHYS - Disordered Systems and Neural Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140045226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Minimal cyclic behavior in sheared amorphous solids 剪切无定形固体中的最小循环行为

arXiv - PHYS - Disordered Systems and Neural Networks Pub Date : 2024-03-04 DOI: arxiv-2403.01679

Chloe W. Lindeman, Sidney R. Nagel

引用次数: 0

Disconnectivity graphs for visualizing combinatorial optimization problems: challenges of embedding to Ising machines 用于组合优化问题可视化的断连图：嵌入伊辛机的挑战

arXiv - PHYS - Disordered Systems and Neural Networks Pub Date : 2024-03-02 DOI: arxiv-2403.01320

Dmitrii Dobrynin, Adrien Renaudineau, Mohammad Hizzani, Dmitri Strukov, Masoud Mohseni, John Paul Strachan

{"title":"Disconnectivity graphs for visualizing combinatorial optimization problems: challenges of embedding to Ising machines","authors":"Dmitrii Dobrynin, Adrien Renaudineau, Mohammad Hizzani, Dmitri Strukov, Masoud Mohseni, John Paul Strachan","doi":"arxiv-2403.01320","DOIUrl":"https://doi.org/arxiv-2403.01320","url":null,"abstract":"Physics-based Ising machines (IM) have risen to the challenge of solving hard\u0000combinatorial optimization problems with higher speed and better energy\u0000efficiency. Generally, such dedicated systems employ local search heuristics to\u0000traverse energy landscapes in searching for optimal solutions. Extending\u0000landscape geometry visualization tools, disconnectivity graphs, we quantify and\u0000address some of the major challenges met by IMs in the field of combinatorial\u0000optimization. Using efficient sampling methods, we visually capture landscapes\u0000of problems having diverse structure and hardness and featuring strong\u0000degeneracies, which act as entropic barriers for IMs. Furthermore, we\u0000investigate energy barriers, local minima, and configuration space clustering\u0000effects caused by locality reduction methods when embedding combinatorial\u0000problems to the Ising hardware. For this purpose, we sample disconnectivity\u0000graphs of PUBO energy landscapes and their different QUBO mappings accounting\u0000for both local minima and saddle regions. We demonstrate that QUBO energy\u0000landscape properties lead to the subpar performance of quadratic IMs and\u0000suggest directions for their improvement.","PeriodicalId":501066,"journal":{"name":"arXiv - PHYS - Disordered Systems and Neural Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140032840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Mobility edges in non-Hermitian models with slowly varying quasi-periodic disorders 具有缓慢变化准周期紊乱的非ermitian模型中的流动边缘

arXiv - PHYS - Disordered Systems and Neural Networks Pub Date : 2024-02-27 DOI: arxiv-2402.17266

Qiyun Tang, Yan He

引用次数: 0