Feasible platform to study negative temperatures

TL;DR

This paper proposes a versatile experimental platform for studying negative temperatures using engineered Hamiltonians, enabling controlled population inversion across various quantum systems.

Contribution

It introduces a general model for achieving negative temperatures, applicable to multiple quantum platforms, with demonstrations of unique effects like lack of thermalization and cooling by heating.

Findings

Demonstrated absence of thermalization in inverted population systems

Showed cooling by heating effect in unconventional quantum systems

Provided a feasible experimental setup for negative temperature studies

Abstract

We afford an experimentally feasible platform to study Boltzmann negative temperatures. Our proposal takes advantage of well-known techniques of engineering Hamiltonian to achieve steady states with highly controllable population inversion. Our model is completely general and can be applied in a number of contexts, such as trapped ions, cavity-QED, quantum dot coupled to optical cavities, circuit-QED, and so on. To exemplify, we use Hamiltonian models currently used in optical cavities and trapped ion domain, where the level of precision achieved the control of the freedom degrees of a single atom inside a cavity/trapped ion. We show several interesting effects such as absence of thermalization between systems with inverted population and cooling by heating in these unconventional systems.