Transport in a System with a Tower of Quantum Many-Body Scars

TL;DR

This paper investigates unusual transport behaviors in a spin-1 model with quantum many-body scars, revealing a dynamical symmetry that affects autocorrelation decay and transport properties, supported by numerical evidence.

Contribution

It uncovers a new dynamical symmetry linked to quantum many-body scars that influences transport and autocorrelation decay in a spin-1 model, and proposes a generalized eigenstate thermalization hypothesis.

Findings

Unconventional transport phenomena observed in the model.

Dynamical symmetry restricts the Hilbert space of scars.

Excited states near scars sustain transport.

Abstract

We report the observation of unconventional transport phenomena in a spin-1 model that supports a tower of quantum many-body scars, and we discuss their properties uncovering their peculiar nature. In quantum many-body systems, the late-time dynamics of local observables are typically governed by conserved operators with local densities, such as energy and magnetization. In the model under investigation, however, there is an additional dynamical symmetry restricted to the subspace of the Hilbert space spanned by the quantum many-body scars. The latter significantly slows the decay of autocorrelation functions of certain coherent states of quantum many-body scars and is responsible for the unconventional form of transport that we detect numerically. We show that excited states with energy close to that of the quantum many-body scars play a crucial role in sustaining the transport. Finally, we propose a generalized eigenstate thermalization hypothesis to describe specific properties of states with energy close to the scars.