Generalized quantum interference of correlated photon pairs

TL;DR

This paper introduces a comprehensive two-photon interferometric scheme that unifies Hong-Ou-Mandel interference and path-entangled photon states, enabling advanced quantum measurements and source characterization.

Contribution

It presents the first experimental demonstration of a generalized two-photon interferometry scheme combining key quantum interference effects.

Findings

Demonstrated combined Hong-Ou-Mandel and path-entangled interference

Enabled direct estimation of joint spectral intensity of photon pairs

Revealed coherence properties within a single interferometric setup

Abstract

Superposition and indistinguishablility between probability amplitudes have played an essential role in observing quantum interference effects of correlated photons. The Hong-Ou-Mandel interference and interferences of the path-entangled photon number state are of special interest in the field of quantum information technologies. However, a fully generalized two-photon quantum interferometric scheme accounting for the Hong-Ou-Mandel scheme and path-entangled photon number states has not yet been proposed. Here we report the experimental demonstrations of the generalized two-photon interferometry with both the interferometric properties of the Hong-Ou-Mandel effect and the fully unfolded version of the path-entangled photon number state using photon-pair sources, which are independently generated by spontaneous parametric down-conversion. Our experimental scheme explains two-photon interference fringes revealing single- and two-photon coherence properties in a single interferometer setup. Using the proposed interferometric measurement, it is possible to directly estimate the joint spectral intensity of a photon pair source.