Dynamical Quantum Phase Transition Without An Order Parameter

TL;DR

This paper investigates disorder-induced dynamical quantum phase transitions in the Ising model, revealing critical times and spectral features responsible, and emphasizes that these transitions lack a local order parameter.

Contribution

It identifies the spectral mechanisms behind disorder-induced dynamical phase transitions and shows they occur without a local order parameter.

Findings

Disorder introduces new critical times in the Ising model dynamics.

A critical disorder strength induces the dynamical phase transition.

The transition is non-topological and lacks a local order parameter.

Abstract

Short-time dynamics of many-body systems may exhibit non-analytical behavior of the systems' properties at particular times, thus dubbed dynamical quantum phase transition. Simulations showed that in the presence of disorder new critical times appear in the quench evolution of the Ising model. We study the physics behind these new critical times. We discuss the spectral features of the Ising model responsible for the disorder-induced phase transitions. We found the critical value of the disorder sufficient to induce the dynamical phase transition as a function of the number of spins. Most importantly, we argue that this dynamical phase transition while non-topological lacks a local order parameter.