Quantum Key Distribution Using an Integrated Quantum Emitter in Hexagonal Boron Nitride

Ali Al-Juboori, Helen Zhi Jie Zeng, Minh Anh Phan Nguyen, Xiaoyu Ai, Arne Laucht, Alexander Solntsev, Milos Toth, Robert Malaney, Igor Aharonovich

Published 2023-02-13Version 1

Quantum Key Distribution (QKD) is considered the most immediate application to be widely implemented amongst a variety of potential quantum technologies. QKD enables sharing secret keys between distant users, using photons as information carriers. The current challenge is to implement these protocols in practice, for real-world conditions, in a robust, and compact manner. Single Photon Sources (SPS) in solid-state materials are prime candidates in this respect. Here, we demonstrate a room temperature, discrete-variable quantum key distribution system using a bright single photon source in hexagonal-boron nitride, operating in free-space. Employing an integrated, "plug and play" photon source system, we have generated keys with one million bits length, and demonstrated a secret key of approximately 70,000 bits, at a quantum bit error rate of 6%, with $\varepsilon$-security of $10^{-10}$. Emphasis was put on the inclusion of all known effects impacting the derived security level, thereby demonstrating the most trustworthy QKD system realised with SPSs to date. Our results will be important to achieve meaningful progress with deterministic room-temperature QKD systems.