Enhanced Whispering Gallery Mode Phase Shift using Indistinguishable Photon Pairs

TL;DR

This paper theoretically demonstrates that using indistinguishable photon pairs in a WGM resonator coupled with an MZI enhances phase shift detection and noise performance, advancing quantum sensing capabilities.

Contribution

It introduces a novel approach combining photon pairs with WGM resonators and MZI to improve phase shift sensitivity and noise reduction in quantum sensing.

Findings

Bimodal coincidence transmission spectrum observed with indistinguishable photon pairs.

Doubling of WGM phase shift for path-entangled states in the interferometer.

At least four-fold improvement in signal-to-noise ratio for resonance shift measurement.

Abstract

We present a theoretical investigation of a whispering gallery mode (WGM) resonator coupled to a Mach-Zehnder interferometer (MZI) and show a bimodal coincidence transmission spectrum when the input state is an indistinguishable photon pair. This is due to the doubled WGM phase shift experienced by the path-entangled state in the interferometer. Further, we model the noise in a WGM resonance shift measurement comparing photon pairs with a coherent state. At least a four-fold improvement in the signal-to-noise ratio (SNR) is possible, with clear implications for quantum-enhanced WGM sensing.