Abstract
The secret key rate is one of the main obstacles to the practical application of continuous-variable quantum key distribution (CVQKD). In this paper, we propose a multiplexing scheme to increase the secret key rate of the CVQKD system with orbital angular momentum (OAM). The propagation characteristics of a typical vortex beam, involving the Laguerre–Gaussian (LG) beam, are analyzed in an atmospheric channel for the Kolmogorov turbulence model. Discrete modulation is utilized to extend the maximal transmission distance. We show the effect of the transmittance of the beam over the turbulent channel on the secret key rate and the transmission distance. Numerical simulations indicate that the OAM multiplexing scheme can improve the performance of the CVQKD system and hence has potential use for practical high-rate quantum communications.
Highlights
We find that the effective transmittance is negatively correlated with the intensity of atmospheric turbulence, the transmission distance, and the angular mode number of orbital angular momentum (OAM)
We have suggested an OAM-based continuousvariable quantum key distribution (CVQKD) protocol with discrete modulation over atmospheric turbulence channels to achieve high-rate quantum communications
OAM multiplexing scheme is designed and the optical propagation characteristics of the LG beam are analyzed in this work
Summary
Apart from the above-mentioned multiplexing schemes, orbital angular momentum (OAM) multiplexing is a novel multiplexing technology with low complexity and high spectral efficiency for short-distance communication [30,31]. The simulation results show that in the CVQKD system based on OAM, the larger the angular mode number, the greater the influence of atmospheric turbulence on the mode, the lower the secret key rate, and the shorter the maximum transmission distance.
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