Signatures of many-body localisation in a system without disorder and the relation to a glass transition

TL;DR

This paper investigates a disorder-free quantum spin system showing signs of many-body localisation, revealing a connection to glass transitions and suggesting the MBL transition extends across the entire spectrum.

Contribution

It demonstrates that a disorder-free quantum spin system exhibits MBL signatures and links this to a known glass transition, extending the understanding of MBL beyond disordered systems.

Findings

Spectral and dynamical properties change at a critical coupling.

MBL signatures are observed in a system without quenched disorder.

The MBL transition appears to be present throughout the spectrum.

Abstract

We study a quantum spin system with local bilinear interactions and without quenched disorder which seems to display characteristic signatures of a many-body localisation (MBL) transition. From direct diagonalisation of small systems, we find a change in certain dynamical and spectral properties at a critical value of a coupling, from those characteristic of a thermalising phase to those characteristic of a MBL phase. The system we consider is known to have a quantum phase transition in its ground-state in the limit of large size, related to a first-order active-to-inactive phase transition in the stochastic trajectories of an associated classical model of glasses. Our results here suggest that this transition is present throughout the spectrum of the system in the large size limit. These findings may help understand the connection between MBL and structural glass transitions.