Nonlinear Dynamics and Strong Cavity Cooling of Levitated Nanoparticles

TLDR

Optomechanical systems couple light to mechanical motion, and nonlinear coupling opens access to rich quantum and classical physics. The study investigates a dynamic, nonlinear optomechanical system of a levitated nanosphere cooled in a hybrid electro‑optical trap. An optical cavity provides simultaneous readout of linear and quadratic light‑matter coupling while cooling the nanosphere to millikelvin temperatures in high vacuum for indefinite periods. Cooling of both linear and nonlinear motion achieved a 10⁵‑fold reduction in phonon number, reaching occupancies of 100–1000, demonstrating that cavity cooling of a levitated object to the quantum ground state is now within reach.

Abstract

Optomechanical systems explore and exploit the coupling between light and the mechanical motion of matter. A nonlinear coupling offers access to rich new physics, in both the quantum and classical regimes. We investigate a dynamic, as opposed to the usually studied static, nonlinear optomechanical system, comprising of a nanosphere levitated and cooled in a hybrid electro-optical trap. An optical cavity offers readout of both linear-in-position and quadratic-in-position (nonlinear) light-matter coupling, whilst simultaneously cooling the nanosphere to millikelvin temperatures for indefinite periods of time in high vacuum. We observe cooling of the linear and non-linear motion, leading to a $10^5$ fold reduction in phonon number $n_p$, attaining final occupancies of $n_p = 100-1000$. This work puts cavity cooling of a levitated object to the quantum ground-state firmly within reach.