Quantum Quenches in Free Field Theory: Universal Scaling at Any Rate

TL;DR

This paper investigates the universal scaling behaviors in quantum quenches within free field theories, analyzing the transition from fast to slow quenches and their effects on system dynamics.

Contribution

It provides an exact analysis of scalar and fermionic free field theories across all quench rates, revealing a smooth crossover in one-point functions between different scaling regimes.

Findings

Renormalized one-point functions exhibit a smooth crossover between regimes.

Exact solutions are obtained for all quench rates in free field theories.

Universal scaling behaviors are confirmed across different quench speeds.

Abstract

Quantum quenches display universal scaling in several regimes. For quenches which start from a gapped phase and cross a critical point, with a rate slow compared to the initial gap, many systems obey Kibble-Zurek scaling. More recently, a different scaling behaviour has been shown to occur when the quench rate is fast compared to all other physical scales, but still slow compared to the UV cutoff. We investigate the passage from fast to slow quenches in scalar and fermionic free field theories with time dependent masses for which the dynamics can be solved exactly for all quench rates. We find that renormalized one point functions smoothly cross over between the regimes.