Universal dynamics of inhomogeneous quantum phase transitions: suppressing defect formation

TL;DR

This paper investigates how inhomogeneity in quantum systems affects defect formation during phase transitions, revealing a universal suppression mechanism that enhances adiabaticity and reduces excitations.

Contribution

It introduces a universal framework for understanding defect suppression in inhomogeneous quantum phase transitions, supported by analysis of a quantum Ising chain.

Findings

Defect density decreases with slower quench rates.

Inhomogeneity leads to steeper power-law suppression of defects.

Universal behavior observed across different inhomogeneous systems.

Abstract

In the nonadiabatic dynamics across a quantum phase transition, the Kibble-Zurek mechanism predicts that the formation of topological defects is suppressed as a universal power law with the quench time. In inhomogeneous systems, the critical point is reached locally and causality reduces the effective system size for defect formation to regions where the velocity of the critical front is slower than the sound velocity, favoring adiabatic dynamics. The reduced density of excitations exhibits a much steeper dependence on the quench rate and is also described by a universal power-law, that we demonstrated in a quantum Ising chain.