Implementation of Two Way Free Space Quantum Key Distribution

TL;DR

This paper demonstrates a free space implementation of the two-way LM05 quantum key distribution protocol, achieving secure key rates and analyzing its robustness against channel loss and attacks.

Contribution

First experimental demonstration of two-way LM05 QKD protocol over free space with high secure key rate and loss tolerance.

Findings

Secure key generation rate of 3.54 kbits/sec

Quantum bit error rate of 3.34%

Maximum channel loss for security is 5.68 dB

Abstract

We report an implementation over free space medium of a two way four states quantum key distribution (QKD) protocol namely the LM05. The fully automated setup demonstrated a secure key generation rate of 3.54 kbits per second and quantum bit error rate (QBER) of 3.34% at mean photon number ({\mu}) = 0.15. The maximum tolerable channel loss for secure key generation considering Photon Number Splitting (PNS) attack, was 5.68 [dB]. The result successfully demonstrated the feasibility of a two way QKD protocol implementation over free space medium.