Signal-to-noise-ratio amplification based on symmetry breaking induced by the Sagnac effect

A conventional quantum detection device is unable to distinguish between an input signal and the accompanying noise. This kind of indistinguishability forms a response symmetry to the detection system, and the detection accuracy is limited by the initial signal-to-noise ratio (SNR). We study this limiting problem in an optomechanical angular velocity detection device. By further analyzing the system dynamics in the frequency domain, we find that the indistinguishability between signal and noise can be effectively eliminated by the classical Sagnac effect, which induces the symmetry-breaking response to the detection system. In this case, the SNR can be significantly enhanced, even if the strength of the Sagnac effect is much lower than the input noise. The mechanism of SNR enhancement is illustrated by defining a criterion to quantify the degree of symmetry breaking. In addition, the feasibility of the scheme is also discussed, which offers a path to improve the detection accuracy by breaking the indistinguishability between the signal and noise.