Slow Nonthermalizing Dynamics in a Quantum Spin Glass

TL;DR

This paper investigates the slow, nonthermalizing quantum dynamics in a 1D spin-glass system, revealing a regime where glassy order persists due to suppressed resonance avalanches, distinct from many-body localization.

Contribution

It introduces a detailed analysis of quantum spin-glass dynamics showing a regime of slow relaxation caused by a power-law soft gap, different from conventional MBL.

Findings

Persistence of spin-glass order at low energies

Resonance suppression leads to slow dynamics

Potential realization in trapped ion systems

Abstract

Spin glasses and many-body localization (MBL) are prime examples of ergodicity breaking, yet their physical origin is quite different: the former phase arises due to rugged classical energy landscape, while the latter is a quantum-interference effect. Here we study quantum dynamics of an isolated 1d spin-glass under application of a transverse field. At high energy densities, the system is ergodic, relaxing via resonance avalanche mechanism, that is also responsible for the destruction of MBL in non-glassy systems with power-law interactions. At low energy densities, the interaction-induced fields obtain a power-law soft gap, making the resonance avalanche mechanism inefficient. This leads to the persistence of the spin-glass order, as demonstrated by resonance analysis and by numerical studies. A small fraction of resonant spins forms a thermalizing system with long-range entanglement, making this regime distinct from the conventional MBL. The model considered can be realized in systems of trapped ions, opening the door to investigating slow quantum dynamics induced by glassiness.