Quantum Key Distribution Using a Quantum Emitter in Hexagonal Boron Nitride

TL;DR

This paper demonstrates a practical, room-temperature quantum key distribution system using a solid-state single photon source in hexagonal boron nitride, achieving secure key exchange over free-space links.

Contribution

It presents the first proof-of-concept finite-key BB84 QKD system utilizing hBN defects as a bright, room-temperature single photon source in free-space.

Findings

Generated keys with over one million bits length.

Achieved a secret key of approximately 70,000 bits.

Maintained a quantum bit error rate of 6% with high security level.

Abstract

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. An ongoing endeavour is to implement these protocols in practice in a robust, and compact manner so as to be efficiently deployable in a range of real-world scenarios. 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 easily interchangeable 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 $10^{-10}$. Our work demonstrates the first proof of concept finite-key BB84 QKD system realised with hBN defects.