Secure Quantum Key Distribution Using a Room-Temperature Quantum Emitter

Abstract

On-demand generation of single photons from solid-state quantum emitters is essential to build practical quantum networks and QKD systems by potentially enabling higher secure key rates (SKR) and lower quantum bit error rates (QBER) in short-range distances. Room-temperature operation is particularly important as it eliminates the need for bulky cryogenic setups, reducing complexity and cost for real-world applications. In this work, we showcase the versatility of defects in hexagonal boron nitride (hBN) at room temperature by implementing the B92 protocol. Our experiments yield a sifted key rate (SiKR) of 17.5 kbps with a QBER of 6.49% at a dynamic polarization encoding rate of 40 MHz, and finite-key analysis provides a SKR of 7 kbps, one of the highest achieved for a room-temperature single photon source. We analyzed the non-decoy efficient BB84 using our hBN emitter and other promising quantum dot source for QKD, and compare their key performance with a single quantum repeater scenario. We also explore potential applications of hBN defects beyond QKD and analyze scenarios that could outperform conventional point-to-point QKD schemes. These results underscore the promise of hBN emitters for advancing quantum communication technologies.