Continuous-variable quantum key distribution with time-division dual-quadrature homodyne detection

We propose a novel heterodyne detection scheme for continuous-variable quantum key distribution (CVQKD), which measures both quadrature components of a quantum signal encoded in optical phase space. The proposed method uses time division to achieve identical performance to conventional heterodyne detection with only a single homodyne detection system. Our method also uses a Faraday-Michelson interferometer to make it independent of polarization drift and eliminate the need for dynamic polarization control. Our method is experimentally demonstrated using the Gaussian-modulated coherent-states (GMCS) protocol over a 20.06 km optical fiber channel, achieving an expected secret key rate of up to 0.187 Mbps.

Automated summary

A novel heterodyne detection scheme for continuous-variable quantum key distribution (CVQKD) is proposed in this study, which measures both quadrature components of a quantum signal encoded in optical phase space. The proposed method achieves identical performance to conventional heterodyne detection with only a single homodyne detection system using time division. Additionally, a Faraday-Michelson interferometer is utilized in our method to make it independent of polarization drift and eliminate the need for dynamic polarization control. Experimental results demonstrate that our method, using the Gaussian-modulated coherent-states (GMCS) protocol, achieves an expected secret key rate of up to 0.187 Mbps over a 20.06 km optical fiber channel.