Generating entangled photon pairs in a parallel crystal geometry

TL;DR

This paper explores a novel parallel crystal geometry using BBO crystals to generate brighter, more robust polarization-entangled photon pairs for free-space quantum key distribution, with preliminary results indicating potential improvements.

Contribution

Introduces a new parallel crystal configuration for entangled photon generation that enhances brightness and environmental robustness.

Findings

Preliminary results suggest increased source brightness.

The configuration is potentially more robust to environmental changes.

Method improves entangled photon source performance for QKD.

Abstract

We present recent findings towards developing brighter entangled photon sources in critically phase matched (CPM) nonlinear crystals. Specifically, we use type-I collinear phase matching at non-degenerate wavelengths in parallel \b{eta}-Barium Borate (BBO) crystals to generate pairs of polarization entangled photons for free-space quantum key distribution (QKD). We first review the entangled source configuration and then discuss ways to further improve the source brightness by means of tailoring the pump and collection modes. We present preliminary results that may lead to brighter entangled photon sources that are intrinsically robust to changes in their environment.