Lifetimes of local excitations in disordered dipolar quantum systems

TL;DR

This paper investigates the relaxation dynamics of local excitations in disordered dipolar quantum systems, revealing diverse scaling laws for energy and dephasing times across different dimensions and physical realizations.

Contribution

It provides a comprehensive analysis of excitation lifetimes in disordered dipolar systems, including electron glasses and quantum dipoles, with new insights into their scaling behaviors.

Findings

Identification of scaling laws for relaxation and dephasing times.

Analysis of dimensional crossover effects in quasi-two-dimensional systems.

Comparison of relaxation dynamics across different physical platforms.

Abstract

When a strongly disordered system of interacting quantum dipoles is locally excited, the excitation relaxes on some (potentially very long) timescale. We analyze this relaxation process, both for electron glasses with strong Coulomb interactions - in which particle-hole dipoles are emergent excitations - and for systems (e.g., quantum magnets or ultracold dipolar molecules) made up of microscopic dipoles. We consider both energy relaxation rates ($T_1$ times) and dephasing rates ($T_2$ times), and their dependence on frequency, temperature, and polarization. Systems in both two and three dimensions are considered, along with the dimensional crossover in quasi-two dimensional geometries. A rich set of scaling laws is found.