Typical relaxation of perturbed quantum many-body systems

TL;DR

This paper extends a relaxation theory for perturbed quantum many-body systems, providing an analytical prediction for observable dynamics based on perturbation strength and range, validated by numerical comparisons.

Contribution

It introduces an analytical approach to predict relaxation in perturbed quantum systems using a typicality framework and universality of random matrix solutions.

Findings

Analytical prediction matches numerical simulations.

Broader range of perturbation strengths covered.

Universality of solutions applies to various perturbations.

Abstract

We substantially extend our relaxation theory for perturbed many-body quantum systems from [Phys. Rev. Lett. 124, 120602 (2020)] by establishing an analytical prediction for the time-dependent observable expectation values which depends on only two characteristic parameters of the perturbation operator: its overall strength and its range or band width. Compared to the previous theory, a significantly larger range of perturbation strengths is covered. The results are obtained within a typicality framework by solving the pertinent random matrix problem exactly for a certain class of banded perturbations and by demonstrating the (approximative) universality of these solutions, which allows us to adopt them to considerably more general classes of perturbations. We also verify the prediction by comparison with several numerical examples.