Locating quantum critical points with Kibble-Zurek quenches

TL;DR

The paper proposes a non-equilibrium susceptibility method during finite-rate quenches to locate quantum critical points, demonstrating universal scaling and verifying in solvable models, with potential experimental applications.

Contribution

It introduces a novel scheme using non-equilibrium susceptibility peaks during quenches to precisely identify quantum critical points, supported by theoretical scaling analysis and exact model verification.

Findings

Peaks of non-equilibrium susceptibility appear on opposite sides of the critical point.

The method allows narrowing down the critical point's location based on peak positions.

Universal scaling laws with quench time are derived and confirmed in models.

Abstract

We describe a scheme for finding quantum critical points based on studies of a non-equilibrium susceptibility during finite-rate quenches taking the system from one phase to another. We assume that two such quenches are performed in opposite directions, and argue that they lead to formation of peaks of a non-equilibrium susceptibility on opposite sides of a critical point. Its position is then narrowed to the interval marked off by these values of the parameter driving the transition, at which the peaks are observed. Universal scaling with the quench time of precision of such an estimation is derived and verified in two exactly solvable models. Experimental relevance of these results is expected.