Sensing directional noise baths in levitated optomechanics

Year: 2024

Authors: Gosling J.M.H., Pontin A., Iacoponi J.H., Barker P.F., Monteiro T.S.

Autors Affiliation: UCL, Dept Phys & Astron, Gower St, London WC1E 6BT, England.

Abstract: Optomechanical devices are being harnessed as sensors of ultraweak forces for applications ranging from inertial sensing to the search for the elusive dark matter. For the latter, there is a focus on detection of either higher energy single recoils or ultralight, narrow-band sources; a directional signal is expected. However, the possibility of searching for a stochastic stream of weak impulses, or more generally a directional broadband signal, need not be excluded; with this and other applications in mind, we apply Gaussian white noise impulses with a well defined direction Psi to a levitated nanosphere trapped and 3D cooled in an optical tweezer. We find that cross-correlation power spectra offer a calibration-free distinctive signature of the presence of a directional broadband force and its orientation quadrant, unlike normal power spectral densities (PSDs). We obtain excellent agreement between theoretical and experimental results. With calibration we are able to measure the angle Psi, akin to a force compass in a plane. We discuss prospects for extending this technique into the quantum regime and compare the expected behavior of quantum baths and classical baths.

Journal/Review: PHYSICAL REVIEW RESEARCH

Volume: 6 (1)      Pages from: 13129-1  to: 13129-13

More Information: The authors would like to acknowledge helpful discussions with Markus Rademacher, Hayden Fu, Fiona Alder, and Marko Toros. J.H.I. acknowledges an EPSRC DTP studentship. J.M.H.G. acknowledges funding from the Science and Technology Facilities Council (STFC) Grant No. ST/W006170/1. The authors acknowledge funding from the Engineering and Physical Sciences Research Council (EPSRC) Grant No. EP/W029626/1.r Engineering and Physical Sciences Research Council (EP-SRC) Grant No. EP/W029626/1.
KeyWords: Quantum Control; Nanoparticle; Motion
DOI: 10.1103/PhysRevResearch.6.013129