Cavity Optomechanics with a Bose-Einstein Condensate

TLDR

Cavity optomechanics studies the coupling between a mechanical oscillator and the electromagnetic field in a cavity. We report a cavity optomechanical system where a Bose‑Einstein condensate’s collective density excitation acts as the mechanical oscillator coupled to the cavity field. The experiment reaches the strong‑coupling regime, with a single excitation of the condensate’s density mode markedly influencing the cavity field. A few photons in the ultrahigh‑finesse cavity trigger strongly driven back‑action dynamics that agree quantitatively with a cavity optomechanical model, opening new avenues for exploring quantum‑regime mechanical oscillators and the classical‑quantum boundary.

Abstract

Cavity optomechanics studies the coupling between a mechanical oscillator and the electromagnetic field in a cavity. We report on a cavity optomechanical system in which a collective density excitation of a Bose-Einstein condensate serves as the mechanical oscillator coupled to the cavity field. A few photons inside the ultrahigh-finesse cavity trigger strongly driven back-action dynamics, in quantitative agreement with a cavity optomechanical model. We approach the strong coupling regime of cavity optomechanics, where a single excitation of the mechanical oscillator substantially influences the cavity field. The results open up new directions for investigating mechanical oscillators in the quantum regime and the border between classical and quantum physics.