Backaction suppression in levitated optomechanics using reflective boundaries

TL;DR

This paper theoretically demonstrates that reflective boundaries can significantly reduce laser-induced backaction noise in levitated optomechanical systems, enhancing measurement precision near the Heisenberg limit.

Contribution

It introduces a novel backaction suppression method using reflective boundaries in levitated optomechanics, supported by theoretical analysis and a spherical mirror geometry case study.

Findings

Backaction noise can be reduced using reflective boundaries.

Standing-wave trapping fields are essential for 3D backaction suppression.

The method achieves detection at the Heisenberg limit.

Abstract

We show theoretically that the noise due to laser induced backaction acting on a small nanosphere levitated in a standing-wave trap can be considerably reduced by utilising a suitable reflective boundary. We examine the spherical mirror geometry as a case study of this backaction suppression effect, discussing the theoretical and experimental constraints. We study the effects of laser recoil directly, by analysing optical force fluctuations acting on a dipolar particle trapped at the centre of a spherical mirror. We also compute the corresponding measurement imprecision in an interferometric, shot-noise-limited position measurement, using the formalism of Fisher information flow. Our results show that the standing-wave trapping field is necessary for backaction suppression in three dimensions, and they satisfy the Heisenberg limit of detection.