Correlations generated from high-temperature states: nonequilibrium dynamics in the Fermi-Hubbard model

TL;DR

This paper investigates the nonequilibrium dynamics of the Fermi-Hubbard model following interaction quenches from high-temperature states, revealing transient correlation development and light-cone spreading, with implications for cold atom experiments.

Contribution

It analytically characterizes the dynamics of high-temperature initial states in the Fermi-Hubbard model, highlighting the development of correlations and their distinct features from equilibrium states.

Findings

Transient correlations develop even from uncorrelated high-temperature states

Light-cone spreading of spin and density correlations observed

Localized holes influence local spin correlations, altering their magnitude and sign

Abstract

We study interaction quenches of the Fermi-Hubbard model initiated from various high-temperature and high-energy states, motivated by cold atom experiments, which currently operate above the ordering temperature(s). We analytically calculate the dynamics for quenches from these initial states, which are often strongly-interacting, to the non-interacting limit. Even for high-temperature uncorrelated initial states, transient connected correlations develop. These correlations share many features for all considered initial states. We observe light-cone spreading of intertwined spin and density correlations. The character of these correlations is quite different from their low-temperature equilibrium counterparts: for example, the spin correlations can be ferromagnetic. We also show that an initially localized hole defect affects spin correlations near the hole, suppressing their magnitude and changing their sign.