Sub-Kelvin Parametric Feedback Cooling of a Laser-Trapped Nanoparticle

TL;DR

This paper demonstrates a novel method for cooling a laser-trapped nanoparticle to near its quantum ground state using parametric feedback, without relying on cryogenic precooling or clamping mechanisms.

Contribution

It introduces a technique for parametric feedback cooling of an isolated, clamped-free nanoparticle in all degrees of freedom with a single laser beam.

Findings

Achieved cooling of a nanoparticle in all degrees of freedom.

Demonstrated effective decoupling from thermal environment.

Showed advantages of nanoparticles over microspheres for quantum ground state cooling.

Abstract

Recent experiments have demonstrated the ability to optically cool a macroscopic mechanical oscillator to its quantum ground state by means of dynamic backaction. Such experiments allow quantum mechanics to be tested with mesoscopic objects, and represent an essential step toward quantum optical memories, transducers, and amplifiers. Most oscillators considered so far are rigidly connected to their thermal environment, fundamentally limiting their mechanical Q-factors and requiring cryogenic precooling to liquid helium temperatures. Here we demonstrate parametric feedback cooling of a laser-trapped nanoparticle which is entirely isolated from the thermal bath. The lack of a clamping mechanism provides robust decoupling from internal vibrations and makes it possible to cool the nanoparticle in all degrees of freedom by means of a single laser beam. Compared to laser-trapped microspheres, nanoparticles have the advantage of higher resonance frequencies and lower recoil heating, which are favorable conditions for quantum ground state cooling