Narrowband photon pairs with independent frequency tuning for quantum light-matter interactions

TL;DR

This paper presents a cavity-enhanced SPDC source producing narrowband, independently tunable photon pairs suitable for quantum light-matter interactions, with high spectral purity and potential for quantum networking applications.

Contribution

It introduces a novel, tunable CE-SPDC source with independent control over signal and idler frequencies, enabling efficient interaction with atomic systems.

Findings

Over 97% of correlated photons are in a single 4.3 MHz mode.

Demonstrated atomic spectroscopy with generated photon pairs.

Achieved independent frequency tuning of signal and idler photons.

Abstract

We describe a cavity-enhanced spontaneous parametric down-conversion (CE-SPDC) source for narrowband photon pairs with filters such that over 97% of the correlated photons are in a single mode of 4.3(4) MHz bandwidth. Type-II phase matching, a tuneable-birefringence resonator, MHz-resolution pump tuning, and tuneable Fabry-Perot filters are used to achieve independent signal and idler tuning. We map the CE-SPDC spectrum using difference frequency generation to precisely locate the emission clusters, and demonstrate CE-SPDC driven atomic spectroscopy. The generated photon pairs efficiently interact with neutral rubidium, a well-developed system for quantum networking and quantum simulation. The techniques are readily extensible to other material systems.