Localization and Dynamics in One-dimensional and Two-dimensional Gaussian Disordered Quantum Spin Systems

TL;DR

This study investigates how Gaussian disorder affects many-body localization in one- and two-dimensional quantum spin systems, revealing that disorder breadth, not central value, governs localization transitions, with initial state playing a significant role in certain configurations.

Contribution

It introduces Gaussian disorder parameters in spin systems and analyzes their impact on MBL transitions, especially highlighting the importance of disorder standard deviation over mean value.

Findings

Disorder standard deviation drives localization transition.

Initial state significantly affects localization in ladder models.

Disorder mean value has negligible effect on MBL transition.

Abstract

This paper introduces Gaussian disorder, characterized by two parameters:the expected value and the standard deviation.Studying this type of disorder enhances our understanding of how many-body localization (MBL) transition is influenced by the central value and breadth of disorder.We apply Gaussian disorder to a one-dimensional spin-1/2 chain to reveal its features.Our findings indicate that the crucial parameter driving localization transitions is the standard deviation; as it increases, the system transitions from the ergodic phase to the localized phase, while the expected value has no effect,so the critical factor influencing MBL transition is the breadth of disorder rather than its central value.We then explore Gaussian disorder in two system-environment models (hereafter referred to as the sye-env models, consisting of ladder configuration and staggered configuration),analyzing the mutual influence when they are coupled.We extensively explore the impacts brought about by system disorder,environment disorder,initial state,and the strength of the sys-env interaction.Finally,for theses two different models,we consider the system and environment as a whole,studying how the localization properties of the entire system are influenced by the disorder strength of each chain and the interaction strength between the two chains.In the ladder configuration, we observe a strong dependence on the initial state,which can lead to either the loss or retention of information,whereas no such dependence on the initial state is found in the staggered configuration.We emphasize that when using dynamic indicators to analyze system characteristics, it is essential to consider the influence of different initial states,as this may lead to significant differences under certain structural conditions,and not all initial states can accurately reflect the localization properties of the many-body system.