Quantifying the Momentum Correlation between Two Light Beams by Detecting One

TL;DR

This paper presents a method to measure the transverse momentum correlation between two photons by detecting only one, using induced coherence and interference patterns, which could aid in characterizing entangled photon sources.

Contribution

The authors introduce a novel technique to quantify photon momentum correlations through single-photon detection, enabling potential measurement of continuous variable entanglement.

Findings

Successfully measured momentum correlation via interference visibility

Demonstrated induced coherence without induced emission

Proposed a new approach for characterizing entangled photon sources

Abstract

We report a measurement of the transverse momentum correlation between two photons by detecting only one of them. Our method uses two identical sources in an arrangement, in which the phenomenon of induced coherence without induced emission is observed. In this way, we produce an interference pattern in the superposition of one beam from each source. We quantify the transverse momentum correlation by analyzing the visibility of this pattern. Our approach might be useful for the characterization of correlated photon pair sources and may lead to an experimental measure of continuous variable entanglement, which relies on the detection of only one of two entangled particles.