Optical backaction-evading measurement of a mechanical oscillator.


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Authors
Shomroni, Itay 
Qiu, Liu 
Nunnenkamp, Andreas  ORCID logo  https://orcid.org/0000-0003-2390-7636
Kippenberg, Tobias J 
Abstract

Quantum mechanics imposes a limit on the precision of a continuous position measurement of a harmonic oscillator, due to backaction arising from quantum fluctuations in the measurement field. This standard quantum limit can be surpassed by monitoring only one of the two non-commuting quadratures of the motion, known as backaction-evading measurement. This technique has not been implemented using optical interferometers to date. Here we demonstrate, in a cavity optomechanical system operating in the optical domain, a continuous two-tone backaction-evading measurement of a localized gigahertz-frequency mechanical mode of a photonic-crystal nanobeam cryogenically and optomechanically cooled close to the ground state. Employing quantum-limited optical heterodyne detection, we explicitly show the transition from conventional to backaction-evading measurement. We observe up to 0.67 dB (14%) reduction of total measurement noise, thereby demonstrating the viability of backaction-evading measurements in nanomechanical resonators for optical ultrasensitive measurements of motion and force.

Description
Keywords
quant-ph, quant-ph
Journal Title
Nat Commun
Conference Name
Journal ISSN
2041-1723
2041-1723
Volume Title
10
Publisher
Springer Science and Business Media LLC
Rights
All rights reserved
Sponsorship
The Royal Society (uf130303)
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (732894)
Engineering and Physical Sciences Research Council (EP/M506485/1)