Free space quantum key distribution over 500 meters using electrically driven quantum dot single-photon sources—a proof of principle experiment

Abstract

Highly efficient single-photon sources (SPS) can increase the secure key rate of quantum key distribution (QKD) systems compared to conventional attenuated laser systems. Here we report on a free space QKD test using an electrically driven quantum dot single-photon source (QD SPS) that does not require a separate laser setup for optical pumping and thus allows for a simple and compact SPS QKD system. We describe its implementation in our 500 m free space QKD system in downtown Munich. Emulating a BB84 protocol operating at a repetition rate of 125 MHz, we could achieve sifted key rates of 5–17 kHz with error ratios of 6–9% and ${{\text{g}}^{(2)}}(0)$ -values of 0.39–0.76.

Keywords

• QKD
• quantum key distribution
• quantum dots
• electrically driven
• free space