Amplitude-Phase Modulated CVQKD Protocol

TL;DR

This paper evaluates a discrete modulated CVQKD protocol using amplitude-phase keying with 8 and 16 states, demonstrating improved secret key rates and link distances over conventional methods, especially in low transmittance regimes.

Contribution

It introduces a novel amplitude-phase modulated CVQKD protocol with optimized constellations that outperform traditional schemes in key rate and distance.

Findings

Outperforms conventional $m$-PSK and $m$-APK in secret key rate.

Achieves viable SKRs at low transmittance ($ au<0.2$).

Enhances link distance capabilities.

Abstract

Here we report the performance of a discrete modulated Continuous Variable Quantum Key Distribution protocol based on eight and sixteen state optimal Amplitude Phase Keying constellations with pure loss quantum channel transmission. Our constellations use the same amplitudes and state probability as in an optimal four-state unidimensional constellation model and apply amplitude/phase modulation to the quadratures of coherent states. We compare the obtained results with the performance of conventional $m$-PSK and $m$-APK constellations. The results presented show that protocols that use the proposed constellations outperform the ones based on conventional constellations in both secret key rate and link distance. In special, our protocol is able to accomplish viable SKR's in low transmittance regime, $\tau<0.2$.