A versatile design for resonant guided-wave parametric down-conversion sources for quantum repeaters

TL;DR

This paper introduces a monolithic, integrated resonant photon-pair source based on parametric down-conversion in nonlinear waveguides, capable of generating high-purity, tunable photons suitable for quantum repeaters and various quantum memories.

Contribution

The authors present a versatile design scheme for integrated resonant photon-pair sources with tunable spectral properties, enhancing compatibility with different quantum memories.

Findings

Photon spectral bandwidths range from tens of MHz to 1 GHz.

Central photon frequency can be coarsely tuned via pump, poling, and temperature.

High-purity photons are generated across a wide bandwidth range.

Abstract

Quantum repeaters - fundamental building blocks for long-distance quantum communication - are based on the interaction between photons and quantum memories. The photons must fulfil stringent requirements on central frequency, spectral bandwidth and purity in order for this interaction to be efficient. We present a design scheme for monolithically integrated resonant photon-pair sources based on parametric down-conversion in nonlinear waveguides, which facilitate the generation of such photons. We investigate the impact of different design parameters on the performance of our source. The generated photon spectral bandwidths can be varied between several tens of MHz up to around $1\,$GHz, facilitating an efficient coupling to different memories. The central frequency of the generated photons can be coarsely tuned by adjusting the pump frequency, poling period and sample temperature and we identify stability requirements on the pump laser and sample temperature that can be readily fulfilled with off-the-shelve components. We find that our source is capable of generating high-purity photons over a wide range of photon bandwidths. Finally, the PDC emission can be frequency fine-tuned over several GHz by simultaneously adjusting the sample temperature and pump frequency. We conclude our study with demonstrating the adaptability of our source to different quantum memories.