Quantum noise limit for force sensitivity of linear detectors

TL;DR

This paper establishes fundamental quantum limits on force sensitivity in linear detectors, showing that the ultimate sensitivity bound can be surpassed by optimizing detector-oscillator interactions, thus guiding future high-precision measurement improvements.

Contribution

It proves the quantum limit for force sensitivity in optomechanical detectors and introduces a generalized bound that can be exceeded through tailored interactions.

Findings

Force sensitivity is bounded by the ultimate quantum limit (UQL).

Generalized UQL can be surpassed with proper detector-oscillator coupling.

Results suggest new avenues for enhancing high-sensitivity detection schemes.

Abstract

We prove that the force sensitivity of the conventional optomechanical detector associated with the optical quadrature measurement of the output beam is lower bounded by the so-called ultimate quantum limit (UQL), i.e., the absolute value of the imaginary part of the inverse mechanical susceptibility. Through the linear response theory, we find that the force sensitivity of any linear detector is lower bounded by a generalized UQL, which might beat the usual UQL by properly tailoring the detector-oscillator interaction. We believe that our results open a new direction for improving the performance of high-sensitivity detection schemes.