Experimental demonstration of a Grover-Michelson interferometer

TL;DR

This paper demonstrates a robust, low-resource optical implementation of a four-dimensional Grover coin integrated into a Michelson interferometer, significantly enhancing phase sensitivity and pattern control over traditional systems.

Contribution

It introduces a novel, stable four-port Grover coin for interferometry, replacing the traditional beam-splitter, enabling higher-dimensional mode control and improved phase sensitivity.

Findings

Achieved 97% visibility in intensity interferogram.

Phase sensitivity exceeds that of a standard Michelson interferometer by over an order of magnitude.

Demonstrated stable, resource-efficient implementation of a four-dimensional Grover coin.

Abstract

We present a low-resource and robust optical implementation of the four-dimensional Grover coin, a four-port linear-optical scatterer that augments the low dimensionality of a regular beam-splitter. While prior realizations of the Grover coin required a potentially unstable ring-cavity to be formed, this version of the scatterer does not exhibit any internal interference. When this Grover coin is placed in another system, it can be used for interferometry with a higher-dimensional set of optical field modes. In this case, we formed a Grover-Michelson interferometer, which results when the traditional beam-splitter of a Michelson interferometer is replaced with a four-port Grover coin. This replacement has been shown to remove a phase parameter redundancy in the original Michelson system, now allowing continuous tuning of the shape and slope of the interference pattern. We observed an intensity interferogram with $97\%$ visibility and a phase sensitivity more than an order of magnitude larger than a regular Michelson interferometer. Because this device is readily formed with nearly the same number of optomechanical resources as a Michelson interferometer, but can outperform it drastically in phase delay evaluation, it has a great potential to improve many interferometric sensing and control systems.