Cavity optomechanics with a trapped, interacting Bose-Einstein condensate

TL;DR

This paper explores how a Bose-Einstein condensate interacts with an optical cavity, demonstrating that atomic collisions mainly renormalize parameters and that a single condensate excitation mode effectively couples to light even under strong confinement.

Contribution

It shows that atomic s-wave collisions only renormalize optomechanical parameters and that a single excitation mode remains relevant under strong confinement.

Findings

Atomic collisions renormalize optomechanical parameters.

Single excitation mode couples significantly to light.

The simplified single-mode picture remains valid under strong confinement.

Abstract

The dispersive interaction of a Bose-Einstein condensate with a single mode of a high-finesse optical cavity realizes the radiation pressure coupling Hamiltonian. In this system the role of the mechanical oscillator is played by a single condensate excitation mode that is selected by the cavity mode function. We study the effect of atomic s-wave collisions and show that it merely renormalizes parameters of the usual optomechanical interaction. Moreover, we show that even in the case of strong harmonic confinement---which invalidates the use of Bloch states---a single excitation mode of the Bose-Einstein condensate couples significantly to the light field, that is the simplified picture of a single "mechanical" oscillator mode remains valid.