Coherent detection schemes for subcarrier wave continuous variable quantum key distribution system.

In this paper, we demonstrate different approaches to coherent detection implementation in subcarrier wave quantum communication schemes. In order to extract information from quadrature phase-coded multimode signals, we demonstrate models of homodyne, double homodyne, and heterodyne detection, actively using the properties of such signals to implement. For greater clarity, all mathematical calculations are given in terms of wave optics. The feasibility of the proposed schemes is supported by experiments.