Broadband variational measurement of a classical force using strongly nondegenerate dichromatic optical pump

• Published in: Physics letters. A 2025-01, Vol.531, Article 130171
• Main Authors: Vyatchanin, Sergey P., Matsko, Andrey B.
• Format: Article
• Language: English
• Subjects: Broadband variational measurement; Standard quantum limit
• ISSN: 0375-9601
• DOI: 10.1016/j.physleta.2024.130171

Maximal sensitivity of classical force detectors utilizing nonlinear opto-mechanical transducers is generally defined by the standard quantum limit resulting from the contamination of the detected signal with noncommuting quantum noises. This restriction can be circumvented by the optimal detection protocols. We here show theoretically that interrogating a resonant opto-mechanical displacement transducer with a strongly nondegenerate dichromatic optical probe enables a quantum back-action evading measurement of a classical force acting on the mechanical oscillator being a part of the opto-mechanical transducer. •In broadband variational measurement in order to overcome SQL one has to utilize tree equidistant optical modes and one mechanical modes.•The central optical mode is pumped and the light escaping the two other optical modes is analyzed.•The main difficulty is practical difficulties of physical separation of the two mode outputs which differs by frequency of mechanical oscillator (small in optical domain).•We introduce a detection scheme with two nearly degenerate optical mode doublets detuned from each other by large frequency (tens of GHz).•These doublets can be separated in space and detected without significant optical losses.