Heisenberg limited Sagnac interferometry

TL;DR

This paper demonstrates how entangled photons from parametric down conversion can enhance Sagnac interferometer sensitivity, achieving up to fourfold improvement with multi-photon coincidences, applicable across various source parameters.

Contribution

It introduces a method to use entangled photons to significantly improve Sagnac interferometry sensitivity, extending applicability to arbitrary source conditions.

Findings

Two-photon coincidences double sensitivity

Four-photon coincidences quadruple sensitivity

Applicable to sources with arbitrary pumping and squeezing parameters

Abstract

We show how the entangled photons produced in parametric down conversion can be used to improve the sensitivity of a Sagnac interferometer. Two-photon and four-photon coincidences increases the sensitivity by a factor of two and four respectively. Our results apply to sources with arbitrary pumping and squeezing parameters.