Optical squeezing mediated by levitated oscillators at their quantum ground state

TL;DR

This paper demonstrates optical squeezing below shot-noise level using a levitated nanoparticle's mechanical modes in their quantum ground state, bridging mechanical quantum control with non-classical light.

Contribution

First demonstration of optical squeezing mediated by multiple mechanical oscillators in their quantum ground state using levitated optomechanics.

Findings

Achieved squeezing with a variance of 0.98, 2% below vacuum fluctuations.

Resolved the spectral covariance matrix of the optical field.

Observed squeezing in the 70-95 kHz frequency band.

Abstract

We demonstrate optical squeezing below the shot-noise level generated through the interaction of an optical cavity field with two center-of-mass modes of a levitated nanoparticle, simultaneously cooled to occupation numbers well below unity. By analyzing the quadrature fluctuations of the cavity output through heterodyne detection, we resolve the full spectral covariance matrix of the optical field and map regions of sub-shot-noise squeezing as a function of detection phase and frequency. Operating in the resolved sideband and strong coupling regime where mechanical modes hybridize with the optical mode, we observe consistent squeezing in the band 70-95 kHz with a lowest variance of 0.98 (2$\%$ below vacuum fluctuations). We thus demonstrate optical squeezing mediated by multiple mechanical oscillators in their quantum ground state, bridging mechanical quantum control with non-classical light and establishing levitated optomechanics as a platform for multimode quantum interactions.