Two-Tone Optomechanical Instability and Its Fundamental Implications for Backaction-Evading Measurements
Authors
Shomroni, I
Youssefi, A
Sauerwein, N
Qiu, L
Seidler, P
Kippenberg, TJ
Publication Date
2019-10-30Journal Title
Physical Review X
ISSN
2160-3308
Publisher
American Physical Society
Volume
9
Issue
4
Type
Article
This Version
AM
Metadata
Show full item recordCitation
Shomroni, I., Youssefi, A., Sauerwein, N., Qiu, L., Seidler, P., Malz, D., Nunnenkamp, A., & et al. (2019). Two-Tone Optomechanical Instability and Its Fundamental Implications for Backaction-Evading Measurements. Physical Review X, 9 (4)https://doi.org/10.1103/PhysRevX.9.041022
Abstract
While quantum mechanics imposes a fundamental limit on the precision of
interferometric measurements of mechanical motion due to measurement
backaction, the nonlinear nature of the coupling also leads to parametric
instabilities that place practical limits on the sensitivity by limiting the
power in the interferometer. Such instabilities have been extensively studied
in the context of gravitational wave detectors, and their presence has recently
been reported in Advanced LIGO. Here we observe experimentally and describe
theoretically a new type of optomechanical instability that arises in two-tone
backaction-evading (BAE) measurements, designed to overcome the standard
quantum limit (SQL), and demonstrate the effect in the optical domain with a
photonic crystal nanobeam, and in the microwave domain with a micromechanical
oscillator coupled to a microwave resonator. In contrast to the well-known
oscillatory parametric instability that occurs in single-tone, blue-detuned
pumping, which is characterized by a vanishing effective mechanical damping,
the parametric instability in balanced two-tone optomechanics is exponential,
and is a result of small detuning errors in the two pump frequencies. Its
origin can be understood in a rotating frame as the vanishing of the effective
mechanical frequency due to an optical spring effect. Counterintuitively, the
instability occurs even in the presence of perfectly balanced intracavity
fields, and can occur for both signs of detuning. We find excellent
quantitative agreement with our theoretical predictions. Since the constraints
on tuning accuracy become stricter with increasing probe power, it imposes a
fundamental limitation on BAE measurements, as well as other two-tone schemes.
In addition to introducing a new limitation in two-tone BAE measurements, the
results also introduce a new type of nonlinear dynamics in cavity
optomechanics.
Sponsorship
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (732894)
Royal Society (uf130303)
Embargo Lift Date
2022-09-05
Identifiers
External DOI: https://doi.org/10.1103/PhysRevX.9.041022
This record's URL: https://www.repository.cam.ac.uk/handle/1810/296482
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