Experimental Characterization of a Discrete Gaussian-modulated Quantum Key Distribution System

Abstract

Quantum Key Distribution (QKD) utilizes the laws of quantum mechanics to enable a verifiably secure distribution of cryptographic key material between distant parties. When properly implemented alongside a one-time pad encryption scheme, QKD can provide unconditional security which is not possible with modern cryptographic systems. One of the most common QKD protocols, the Gaussian-modulated coherent state (GMCS) protocol can never be truly realized due to the stringent requirements of a true Gaussian modulation. This thesis outlines a method for testing a discrete Gaussian-modulated (DGM) QKD protocol which accounts for the discrete nature of its practical implementation. A proof-of-principle experiment for measuring its performance is presented, and a field programmable gate array (FPGA) controlled phase compensation system is designed for practical implementations.