Free-Space Quantum Key Distribution with Single Photons from Defects in Hexagonal Boron Nitride

TL;DR

This paper demonstrates a proof-of-concept free-space quantum key distribution system using single photons emitted from defects in hexagonal boron nitride at room temperature, achieving a secure key rate of 238 bps.

Contribution

It introduces a novel room-temperature single-photon source from hBN defects integrated into a QKD protocol, advancing practical quantum communication technology.

Findings

Achieved a secure key rate of 238 bps

Maintained a quantum bit error rate of 8.95%

Studied the impact of temporal filtering on QKD performance

Abstract

We present a proof-of-concept demonstration of free-space quantum key distribution (QKD) with single photons generated from an isolated defect in hexagonal boron nitride (hBN). The source, operating at room temperature with a 10% brightness, is integrated into a B92 protocol and a secure key rate (SKR) of 238 bps and a quantum bit error rate (QBER) of 8.95% are achieved with 1 MHz clock rate. The effect of temporal filtering of detected photons on the performance of QKD parameters is also studied. We believe that our results will accelerate the work on improving the performance of optically active defects in hBN and their use in high-performance practical QKD systems.