Phase Transitions in Quantum Many-Body Scars

TL;DR

This paper introduces a novel phase transition phenomenon occurring specifically in quantum many-body scar states, distinguished by their resilience amidst a largely unaffected spectrum, and demonstrates how embedding matrix product states can realize such transitions.

Contribution

It reveals a new type of phase transition in quantum many-body scar states and shows how to realize it by embedding matrix product states into a thermal spectrum.

Findings

Scar state phase transition involves low-entropy states near the transition point.

Embedding matrix product states can induce phase transitions in scar states.

Most of the spectrum remains unaffected during the transition.

Abstract

We propose a type of phase transition in quantum many-body systems, which occurs in highly excited quantum many-body scar states, while most of the spectrum is largely unaffected. Such scar state phase transitions can be realized by embedding a matrix product state, known to undergo a phase transition, as a scar state into the thermal spectrum of a parent Hamiltonian. We find numerically that the mechanism for the scar state phase transition involves the formation or presence of low-entropy states at energies similar to the scar state in the vicinity of the phase transition point.