Purifying quantum-dot light in a coherent frequency interface

TL;DR

This paper presents a method for spectral purification and frequency shifting of quantum dot single photons to the telecom C-band, enhancing their suitability for quantum networks.

Contribution

It introduces a novel approach using difference frequency generation in a Lithium Niobate waveguide for simultaneous spectral purification and frequency conversion.

Findings

Achieved GHz-level emission bandwidths for frequency conversion.

Demonstrated compatibility with high-performance quantum emitters.

Established a pathway for integrating quantum dots into hybrid networks.

Abstract

Quantum networks typically operate in the telecom wavelengths to take advantage of low-loss transmission in optical fibres. However, bright quantum dots (QDs) emitting highly indistinguishable quantum states of light, such as InGaAs QDs, often emit photons in the near infrared thus necessitating frequency conversion (FC) to the telecom band. Furthermore, the signal quality of quantum emissions is crucial for the effective performance of these networks. In this work we report a method for simultaneously implementing spectral purification and frequency shifting of single photons from QD sources to the C-band in a periodically poled Lithium Niobate waveguide. We consider difference frequency generation in the counter-propagating configuration to implement FC with the output emission bandwidth in units of GHz. Our approach establishes a clear path to integrating high-performance single-emitter sources in a hybrid quantum network.