Sympathetic cooling of a membrane oscillator in a hybrid mechanical-atomic system

TL;DR

This paper demonstrates sympathetic cooling of a nanomembrane's vibrations using ultracold atoms, achieving significant temperature reduction and enabling quantum control of low-frequency oscillators in a hybrid optomechanical system.

Contribution

It introduces a novel method to cool a massive nanomembrane via atomic coupling over a macroscopic distance, surpassing previous mass limitations.

Findings

Membrane cooled from room temperature to 650 mK

Large atom-membrane cooperativity achieved

Ground-state cooling potential demonstrated

Abstract

Sympathetic cooling with ultracold atoms and atomic ions enables ultralow temperatures in systems where direct laser or evaporative cooling is not possible. It has so far been limited to the cooling of other microscopic particles, with masses up to $90$ times larger than that of the coolant atom. Here we use ultracold atoms to sympathetically cool the vibrations of a Si$_3$N$_4$ nanomembrane, whose mass exceeds that of the atomic ensemble by a factor of $10^{10}$. The coupling of atomic and membrane vibrations is mediated by laser light over a macroscopic distance and enhanced by placing the membrane in an optical cavity. We observe cooling of the membrane vibrations from room temperature to $650\pm 230$ mK, exploiting the large atom-membrane cooperativity of our hybrid optomechanical system. Our scheme enables ground-state cooling and quantum control of low-frequency oscillators such as nanomembranes or levitated nanoparticles, in a regime where purely optomechanical techniques cannot reach the ground state.