Thermally induced coherence in a Mott insulator of bosonic atoms

TL;DR

This paper demonstrates that in a bosonic Mott insulator, increasing temperature can enhance short-range quantum coherence due to thermally generated defects, challenging conventional expectations.

Contribution

The study provides a theoretical and computational analysis showing temperature-induced coherence enhancement in Mott insulators, a phenomenon verifiable in optical lattice experiments.

Findings

Short-range coherence increases with temperature in Mott insulators.

Thermally produced defects facilitate tunneling and coherence.

Results are consistent with high-precision zero-temperature measurements.

Abstract

Conventional wisdom is that increasing temperature causes quantum coherence to decrease. Using finite temperature perturbation theory and exact calculations for the strongly correlated bosonic Mott insulating state we show a practical counter-example that can be explored in optical lattice experiments: the short-range coherence of the Mott insulating phase can increase substantially with increasing temperature. We demonstrate that this phenomenon originates from thermally produced defects that can tunnel with ease. Since the near zero temperature coherence properties have been measured with high precision we expect these results to be verifiable in current experiments.