Direct Measurement of Photon Recoil from a Levitated Nanoparticle

TL;DR

This paper reports the direct measurement of photon recoil heating in a levitated nanoparticle, providing insights into quantum limits and guiding future quantum control and sensing applications.

Contribution

It introduces a method to measure photon recoil heating directly in a levitated nanoparticle without cavity or cryogenic setups, aligning with theoretical predictions.

Findings

Recoil heating rate measured for various particle sizes and powers

Recoil heating rates agree with theoretical models

Demonstrated cooling of nanoparticle motion to micro-Kelvin temperatures

Abstract

The momentum transfer between a photon and an object defines a fundamental limit for the precision with which the object can be measured. If the object oscillates at a frequency $\Omega_0$, this measurement back-action adds quanta $\hbar\Omega_0$ to the oscillator's energy at a rate $\Gamma_{\rm recoil}$, a process called photon recoil heating, and sets bounds to quantum coherence times in cavity optomechanical systems. Here, we use an optically levitated nanoparticle in ultrahigh vacuum to directly measure $\Gamma_{\rm recoil}$. By means of a phase-sensitive feedback scheme, we cool the harmonic motion of the nanoparticle from ambient to micro-Kelvin temperatures and measure its reheating rate under the influence of the radiation field. The recoil heating rate is measured for different particle sizes and for different excitation powers, without the need for cavity optics or cryogenic environments. The measurements are in quantitative agreement with theoretical predictions and provide valuable guidance for the realization of quantum ground-state cooling protocols and the measurement of ultrasmall forces