Atomic Gases at Negative Kinetic Temperature

TL;DR

This paper demonstrates that atomic gases can be thermalized at negative temperatures in optical lattices, enabling novel cooling methods and the potential to reach Bose-Einstein condensation at negative temperatures.

Contribution

It introduces a feasible method for reversing atomic temperature and achieving Bose-Einstein condensation at negative temperatures in current experimental setups.

Findings

Thermalization at negative temperature is possible in optical lattices.

Negative-temperature ensembles can be cooled via evaporation.

Bose-Einstein condensation can occur at negative temperatures.

Abstract

We show that thermalization of the motion of atoms at negative temperature is possible in an optical lattice, for conditions that are feasible in current experiments. We present a method for reversibly inverting the temperature of a trapped gas. Moreover, a negative-temperature ensemble can be cooled, reducing abs(T), by evaporation of the lowest-energy particles. This enables the attainment of the Bose-Einstein condensation phase transition at negative temperature.