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arXiv:1903.10967 · Physical Review Letters

Quantum-Limited Measurements Using an Optical Cavity with Modulated Intrinsic Loss

Alexander K. Tagantsev, Sergey A. Fedorov

Published Jul 23, 2019• 19 citations
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Abstract

We analyze a cavity optomechanical setup, in which the position of an oscillator modulates the internal optical loss. We show that, in contrast to systems with a fixed internal loss, in such a setup, quantum-limited position measurements can be performed and formulate conditions under which it is possible. Additionally, under these conditions the setup exhibits a number of potential benefits for practical operation, including the complete absence of dynamical backaction and optomechanical instability, rejection of classical laser noise, and thermal fluctuations of cavity frequency from the measurement record. We address a few potential experimental implementations of this setup.

DOI
10.1103/physrevlett.123.043602

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We analyze a cavity optomechanical setup, in which the position of an oscillator modulates the internal optical loss. We show that, in contrast to systems with a fixed internal loss, in such a setup, quantum-limited position measurements can be performed and formulate conditions under which it is possible. Additionally, under these conditions the setup exhibits a number of potential benefits for practical operation, including the complete absence of dynamical backaction and optomechanical instability, rejection of classical laser noise, and thermal fluctuations of cavity frequency from the measurement record. We address a few potential experimental implementations of this setup.
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Conditional dynamics due to continuous optical measurements has successfully been applied for state reconstruction and feedback cooling in optomechanical systems. In this paper, we show that the same measurement techniques can be used to unravel nonclassicality in optomechanical limit cycles. In contrast to unconditional dynamics, our approach gives rise to nonclassical limit cycles even in the sideband-unresolved regime, where the cavity decay rate exceeds the mechanical frequency. We predict a significant reduction of the mechanical amplitude fluctuations for realistic experimental parameters.