Uncovering the Microscopic Mechanism of Slow Dynamics in Quasiperiodic Many-Body Localized Systems

TL;DR

This paper investigates the slow dynamics in quasiperiodic many-body localized systems, revealing a microscopic mechanism involving quantum amplitude modulation that explains the observed behavior and supports MBL phase stability.

Contribution

It identifies a universal modulation mechanism causing slow dynamics in quasiperiodic MBL systems and develops an analytical model to explain these phenomena.

Findings

Structured growth of observables in quasiperiodic systems

Quantum amplitude modulation causes slow dynamics

Analytical model explains behavior across timescales

Abstract

We study the number entropy and quasiparticle width in one-dimensional quasiperiodic many-body localized (MBL) systems and observe slow dynamics that have previously been investigated in detail only in random systems. In contrast, quasiperiodic systems exhibit more structured growth of both observables. We identify the modulation of the Rabi oscillation amplitude of single-particle hoppings as the mechanism underlying the slow growth even deep in the MBL regime. This quantum amplitude modulation and associated beats arise from the interaction between single-particle hopping processes at different positions in the chain. Interestingly, this mechanism is not weakened by increasing the distance between particles and is generic to many-body quantum systems. We develop an analytical model based on the aforementioned mechanism that explains the observed dynamics at all accessible timescales and provides a microscopic picture of the slow dynamics in the MBL regime. Our results are consistent with the stability of the MBL phase in the thermodynamic limit.