A phonon laser in ultra-cold matter

TL;DR

This paper proposes a theoretical model for a phonon laser in ultra-cold atomic gases, demonstrating how collective density oscillations can be coherently amplified through negative Landau damping, with potential applications in quantum technologies.

Contribution

It introduces a novel phonon laser mechanism in ultra-cold gases, extending previous ion-based phonon laser concepts to neutral atomic systems.

Findings

Negative Landau damping enables phonon laser instability.

Threshold conditions and growth rates are derived.

The work generalizes ion phonon lasers to ultra-cold gases.

Abstract

We show the possible excitation of a phonon laser instability in an ultra-cold atomic gas confined in a magneto-optical trap. Such an effect results from a negative Landau damping of the collective density perturbations in the gas, leading to the coherent emission of phonons. This laser instability can be driven by a blue-detuned laser superimposed to the usual red-detuning laser beams which usually provide the cooling mechanism. Threshold conditions, instability growth rates and saturation levels are derived. This work generalizes, on theoretical grounds, the recent results obtained with single ion phonon laser, to an ultra-cold atomic gas, where real phonons can be excited. Future phonon lasers could thus adequately be called phasers.