# Quantum correlations at infinite temperature: the dynamical Nagaoka effect

## TL;DR

This paper demonstrates that quantum correlations can persist at infinite temperature in many-body systems, showing non-classical dynamics and long-lived correlations induced by a single particle in a spin bath, challenging classical expectations.

## Contribution

It provides a novel example of quantum correlations at infinite temperature, revealing non-classical dynamics and long-lived correlations in a featureless spin bath induced by a single particle.

## Key findings

- Quantum correlations persist at infinite temperature.
- Long-lived spin correlations are induced by a single particle.
- Correlations include both antiferromagnetic and ferromagnetic types.

## Abstract

Do quantum correlations play a role in high temperature dynamics of many-body systems? A common expectation is that thermal fluctuations lead to fast decoherence and make dynamics classical. In this paper, we provide a striking example of a single particle created in a featureless, infinite temperature spin bath which not only exhibits non-classical dynamics but also induces strong long-lived correlations between the surrounding spins. We study the non-equilibrium dynamics of a hole created in a fermionic or bosonic Mott insulator in the atomic limit, which corresponds to a degenerate spin system. In the absence of interactions, the spin correlations arise purely from quantum interference, and the correlations are both antiferromagnetic and ferromagnetic, in striking contrast to the equilibrium Nagaoka effect. These results are relevant for several condensed matter spin systems, and should be observable using state of the art bosonic or fermionic quantum gas microscopes.