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We use a tensor network renormalization group method to study random $S=2$ antiferromagnetic Heisenberg chains with alternating bond strength distributions. In the absence of randomness, bond alternation induces two quantum critical points…

强关联电子 · 物理学 2023-12-18 Yen-Tung Lin , Shao-Fu Liu , Pochung Chen , Yu-Cheng Lin

We study Anderson localisation on high-dimensional graphs with spatial structure induced by long-ranged but distance-dependent hopping. To this end, we introduce a class of models that interpolate between the short-range Anderson model on a…

无序系统与神经网络 · 物理学 2026-04-22 Bibek Saha , Sthitadhi Roy

We study a Lindbladian generalization of the Anderson model of localization that describes disordered free fermions coupled to a disordered environment. From finite size scaling of both eigenvalue statistics and participation ratio, we…

无序系统与神经网络 · 物理学 2025-01-30 Foster Thompson , Yi Huang , Alex Kamenev

One of the mysteries in the success of neural networks is randomly initialized first order methods like gradient descent can achieve zero training loss even though the objective function is non-convex and non-smooth. This paper demystifies…

机器学习 · 计算机科学 2019-02-06 Simon S. Du , Xiyu Zhai , Barnabas Poczos , Aarti Singh

The impact of disorder on wave transport has been extensively studied in Hermitian systems, where static randomness gives rise to Anderson localization. In non-Hermitian lattices, static disorder can lead to peculiar transport features,…

无序系统与神经网络 · 物理学 2025-12-01 I. Komis , E. T. Kokkinakis , K. G. Makris , E. N. Economou

In this work we consider general non-Hermitian square random matrices $X$ that include a wide class of random band matrices with independent entries. Whereas the existence of limiting density is largely unknown for these inhomogeneous…

概率论 · 数学 2025-01-22 Yi Han

We study theoretically the competition between directional asymmetric coupling and disorder in a one-dimensional array of quantum emitters chirally coupled through a waveguide mode. Our calculation reveals highly nontrivial phase diagram…

无序系统与神经网络 · 物理学 2022-10-11 G. Fedorovich , D. Kornovan , A. Poddubny , M. Petrov

We propose an anti-parity-time (anti-PT ) symmetric non-Hermitian Su-Schrieffer-Heeger (SSH) model, where the large non-Hermiticity constructively creates nontrivial topology and greatly expands the topological phase. In the anti-PT…

介观与纳米尺度物理 · 物理学 2021-06-07 H. C. Wu , L. Jin , Z. Song

We study spectra of directed networks with inhibitory and excitatory couplings. We investigate in particular eigenvector localization properties of various model networks for different value of correlation among their entries. Spectra of…

无序系统与神经网络 · 物理学 2015-05-20 Sarika Jalan , Guimei Zhu , Baowen Li

In the framework of non-Hermitian photonics, we investigate the interplay between disorder and non-Hermiticity in a one-dimensional Hatano-Nelson lattice. While Anderson localization dictates the wave's evolution in conservative random…

无序系统与神经网络 · 物理学 2025-05-20 E. T. Kokkinakis , K. G. Makris , E. N. Economou

In this paper we introduce Parity-Time ($\cal PT$) symmetric perturbation to a one-dimensional Lieb lattice, which is otherwise $\cal P$-symmetric and has a flat band. In the flat band there are a multitude of degenerate dark states, and…

光学 · 物理学 2016-01-25 Li Ge

We study a non-Hermitian AA model with long-range hopping, $1/r^a$, and different choices of quasiperiodic parameters $\beta$ to be a member of the metallic mean family. We find that when the power-law exponent is in the $a<1$ regime, the…

无序系统与神经网络 · 物理学 2021-12-24 Zhihao Xu , Xu Xia , Shu Chen

Flat, non-dispersive bands and topological phase transition in multiple Su-Schrieffer-Heeger (SSH) chains, cross-linked via periodically arranged nodal points are explored within a tight binding framework. We give analytic prescription,…

介观与纳米尺度物理 · 物理学 2024-11-20 Sauvik Chatterjee , Sougata Biswas , and Arunava Chakrabarti

We experimentally investigate the evolution of linear and nonlinear waves in a realization of the Anderson model using disordered one dimensional waveguide lattices. Two types of localized eigenmodes, flat-phased and staggered, are directly…

We consider a discrete, non-Hermitian random matrix model, which can be expressed as a shift of a rank-one perturbation of an anti-symmetric matrix. We show that, asymptotically almost surely, the real parts of the eigenvalues of the…

概率论 · 数学 2016-11-22 Philippe Sosoe , Uzy Smilansky

We study the Stochastic Gradient Descent (SGD) algorithm in nonparametric statistics: kernel regression in particular. The directional bias property of SGD, which is known in the linear regression setting, is generalized to the kernel…

机器学习 · 统计学 2022-08-30 Yiling Luo , Xiaoming Huo , Yajun Mei

This paper revisits the so-called vanishing gradient phenomenon, which commonly occurs in deep randomly initialized neural networks. Leveraging an in-depth analysis of neural chains, we first show that vanishing gradients cannot be…

机器学习 · 计算机科学 2021-06-08 Antonio Orvieto , Jonas Kohler , Dario Pavllo , Thomas Hofmann , Aurelien Lucchi

The presence of disorder can severely impede wave transport, resulting in the famous Anderson localization. Previous theoretical studies found that Anderson transition can exist in one-dimensional (1D) non-Hermitian disordered rings with…

应用物理 · 物理学 2025-02-13 Wei Wang , Xulong Wang , Guancong Ma

We use a strong-disorder renormalization group (SDRG) method and ground-state quantum Monte Carlo (QMC) simulations to study S=1/2 spin chains with random couplings, calculating disorder-averaged spin and dimer correlations. The QMC…

强关联电子 · 物理学 2016-12-02 Yu-Rong Shu , Dao-Xin Yao , Chih-Wei Ke , Yu-Cheng Lin , Anders W. Sandvik

The Anderson model for independent electrons in a disordered potential is transformed analytically and exactly to a basis of random extended states leading to a variant of augmented space. In addition to the widely-accepted phase diagrams…

强关联电子 · 物理学 2007-05-23 Nigel Goldenfeld , Roger Haydock