Phase-resolved measurement of entangled states via common-path interferometry

TL;DR

This paper introduces a novel method for directly measuring the phase of biphoton entangled states using common-path interferometry, demonstrated with spatial modes, enabling precise phase and geometric phase measurements in quantum systems.

Contribution

The paper presents a new interferometric technique for phase measurement of entangled states using an entangled mode as a collinear reference, applicable to various pure quantum systems.

Findings

Successfully demonstrated phase measurement of biphoton states

Able to directly measure geometric phase accumulation

Applicable to any pure quantum system with an exploitable reference state

Abstract

We propose and experimentally demonstrate a method to directly measure the phase of biphoton states using an entangled mode as a collinear reference. The technique is demonstrated with entangled photonic spatial modes in the Laguerre-Gaussian basis, and it is applicable to any pure quantum system containing an exploitable reference state in its entanglement spectrum. As one particularly useful application, we use the new methodology to directly measure the geometric phase accumulation of entangled photons.