Polarization entanglement by time-reversed Hong-Ou-Mandel interference

TL;DR

This paper introduces an ultra-bright, high-fidelity polarization-entangled photon source using time-reversed Hong-Ou-Mandel interference, eliminating the need for wavelength distinguishability or active stabilization, suitable for quantum applications.

Contribution

It demonstrates a novel entangled photon source leveraging time-reversed Hong-Ou-Mandel interference, achieving high rates and fidelity without active stabilization.

Findings

High pair-generation rate achieved

High-fidelity polarization entanglement demonstrated

No active interferometric stabilization required

Abstract

Sources of entanglement are an enabling resource in quantum technology, and pushing the limits of generation rate and quality of entanglement is a necessary pre-requisite towards practical applications. Here, we present an ultra-bright source of polarization-entangled photon pairs based on time-reversed Hong-Ou-Mandel interference. By superimposing four pair-creation possibilities on a polarization beam splitter, pairs of identical photons are separated into two spatial modes without the usual requirement for wavelength distinguishability or non-collinear emission angles. Our source yields high-fidelity polarization entanglement and high pair-generation rates without any requirement for active interferometric stabilization, which makes it an ideal candidate for a variety of applications, in particular those requiring indistinguishable photons.