Metropolitan quantum key distribution using a GaN-based room-temperature telecommunication single-photon source

TL;DR

This paper demonstrates successful quantum key distribution over metropolitan distances using a room-temperature, telecommunication-wavelength single-photon source based on GaN, enabling practical and long-distance quantum communication without cryogenic cooling.

Contribution

The work introduces a GaN-based room-temperature single-photon source for QKD at telecommunication wavelengths, achieving long-distance secure key distribution in metropolitan environments.

Findings

Achieved a secure key rate of 7.58×10⁻⁷ per pulse over 33 km fiber

Demonstrated QKD over 30 km deployed fiber with a key rate of 6.06×10⁻⁸ per pulse

First successful QKD implementation using a room-temperature GaN-based single-photon source at telecom wavelengths

Abstract

Single-photon sources (SPS) hold the potential to enhance the performance of quantum key distribution (QKD). QKD systems using SPS often require cryogenic cooling, while recent QKD attempts using SPS operating at room-temperature have failed to achieve long-distance transmission due to the SPS not operating at telecommunication wavelength. In this work, we have successfully demonstrated QKD using a room-temperature SPS at telecommunication wavelength. The SPS used in this work is based on point defects hosted by gallium nitride (GaN) thin films grown on sapphire substrates. We employed a time-bin and phase encoding scheme to perform the BB84 and reference-frame-independent QKD protocols over a 33 km fiber spool, achieving a secure key rate of $7.58\times 10^{-7}$ per pulse. Moreover, we also implemented a metropolitan QKD experiment over a 30 km deployed fiber, achieving a secure key rate of $6.06\times 10^{-8}$ per pulse. These results broaden the prospects for future use of SPS in commercial QKD applications.