Universal scaling of quench-induced correlations in a one-dimensional channel at finite temperature

TL;DR

This paper demonstrates that the universal power-law decay of quench-induced correlations in a one-dimensional fermion system persists at finite temperature, with thermal effects causing exponential decay of non-universal components.

Contribution

It shows that the universal $t^{-2}$ decay remains robust at finite temperature, and explores its implications for transport properties and experimental observability.

Findings

Universal $t^{-2}$ decay persists at finite temperature.

Thermal effects cause exponential decay of non-universal power laws.

Universal behavior can be enhanced by tuning probe temperature.

Abstract

It has been shown that a quantum quench of interactions in a one-dimensional fermion system at zero temperature induces a universal power law $\propto t^{-2}$ in its long-time dynamics. In this paper we demonstrate that this behaviour is robust even in the presence of thermal effects. The system is initially prepared in a thermal state, then at a given time the bath is disconnected and the interaction strength is suddenly quenched. The corresponding effects on the long times dynamics of the non-equilibrium fermionic spectral function are considered. We show that the non-universal power laws, present at zero temperature, acquire an exponential decay due to thermal effects and are washed out at long times, while the universal behaviour $\propto t^{-2}$ is always present. To verify our findings, we argue that these features are also visible in transport properties at finite temperature. The long-time dynamics of the current injected from a biased probe exhibits the same universal power law relaxation, in sharp contrast with the non-quenched case which features a fast exponential decay of the current towards its steady value, and thus represents a fingerprint of quench-induced dynamics. Finally, we show that a proper tuning of the probe temperature, compared to that of the one-dimensional channel, can enhance the visibility of the universal power-law behaviour.