Squeezing Enhanced Sagnac Sensing based on SU(1,1) Quantum Interference

TL;DR

This paper introduces a robust, squeezing-enhanced Sagnac interferometer utilizing SU(1,1) interference and an optical parametric amplifier to surpass classical sensitivity limits in rotational sensing.

Contribution

It presents a novel design integrating SU(1,1) interference with a Sagnac loop, achieving super-classical sensitivity in rotation measurements under realistic conditions.

Findings

Achieves sensitivity beyond shot-noise limit using squeezing.

Demonstrates robustness against loss and detector inefficiency.

Provides two detection approaches suitable for practical implementation.

Abstract

We present a simple and robust design for a squeezing-enhanced Sagnac interferometer that employs the concept of SU(1,1) interference to significantly surpass the classical sensitivity limit (shot-noise limit - SNL) in rotational sensing. By strategically placing an optical parametric amplifier (OPA) inside the Sagnac loop, light is automatically squeezed in both forward and backward directions of the loop, which enhances the detectability of a small phase. For measuring the squeezed quadrature, we explore two approaches: Direct detection of the output intensity, which is simple, but requires a high-efficiency photo-detector; and parametric homodyne with an additional OPA, which accepts practical detectors with no efficiency limitation, but is technically more complex. Our analysis demonstrates super-classical sensitivity under most realistic conditions of loss and detector inefficiency, thereby leveraging the resources of squeezing and the principles of SU(1,1) interference, while maintaining compatibility with standard Sagnac configurations.