Frequency-Division Multiplexed CV-QKD System
This work addresses spectral efficiency limitations in quantum key distribution for secure communication, representing an incremental improvement through multiplexing.
The authors tackled the problem of low spectral efficiency in continuous-variable quantum key distribution by proposing a frequency-division multiplexed system, which experimentally achieved a 3.7-fold secret key rate gain and extended performance up to 41.1 km compared to single-channel systems.
We propose a frequency-division multiplexed (FDM) continuous-variable quantum key distribution (CV-QKD) system with enhanced spectral efficiency through dense multiplexing of low-symbol-rate signals. A four-channel 10-Mbaud FDM-CV-QKD system was experimentally demonstrated using Gaussian modulation, a transmitted local oscillator, and homodyne detection. Under a finite-size scenario (N = 10^7), the system achieved a 3.7-fold back-to-back secret key rate gain and outperformed the single-channel system for distances up to 41.1 km.