Modulation Signaling-based Continuous Variable Quantum Key Distribution for Indoor Visible Light Communications

This work proposes and analyzes quadrature-phase shift keying (QPSK)-assisted quantum key distribution (QPSK-QKD) for indoor visible light communication (VLC) systems. The joint probabilities are calculated for QPSK-QKD system to determine analytical expressions for the probability of sifted keys (P
sift
), quantum bit error rate (QBER), error probability for the eavesdropper (P
eve
), and ergodic secret key rate. As a special case of QPSK-QKD, the binary phase-shift keying-assisted QKD (BPSK-QKD) system is also examined in terms of considered performance metrics. Comparative results of QPSK-QKD and BPSK-QKD systems indicate that BPSK-QKD outperforms QPSK-QKD in terms of P
sift
and QBER. However, QPSK-QKD is superior to BPSK-QKD for P
eve
. Finally, it is concluded that based on the requirement, a choice can be made between QPSK-QKD and BPSK-QKD for a VLC system.