Phase shifts vs time delays: Sagnac and Hong-Ou-Mandel

TL;DR

This paper demonstrates that the Sagnac effect can be measured using the Hong-Ou-Mandel effect, emphasizing that the Sagnac effect is fundamentally a time delay rather than a phase shift, which has implications for quantum measurements.

Contribution

It reveals that the Hong-Ou-Mandel effect can be used to measure the Sagnac effect, highlighting its nature as a time delay instead of a phase shift.

Findings

Hong-Ou-Mandel effect is insensitive to phase shifts

Sagnac effect is fundamentally a time delay

Measurement method distinguishes between phase and time delay

Abstract

We point out that the Sagnac effect can be measured by means of the Hong-Ou-Mandel effect. The latter is not sensitive to phase shifts, and thus the Hong-Ou-Mandel Sagnac effect hinges on the fact that the Sagnac effect is, fundamentally, a time delay, not a phase shift.