Polarization-Modulator based Quantum Key Distribution (QKD) Source

In this effort, we present progress towards demonstrating a Decoy-State Quantum Key Distribution (QKD) source which is based on a polarization-modulator and an attenuated pulsed laser that is wavelength stable. A three-state QKD protocol is achieved by the preparing the polarization of the quantum state. The polarization-modulator based QKD source improves security by eliminating several sources of side-channel attacks which are present when using multiple sources to produce different QKD states. The QKD source design is presented along with evaluation of critical subsystems, and the performance is characterized including Quantum Bit Error Rate (QBER), Quantum State Tomography, and achievable Key Rates. The QKD source is designed to operate under compact Size, Weight, and Power (SWaP) limitations. Applications of the Polarization-Modulator QKD source include deployment in future mobile quantum networks including Unmanned-Aerial Vehicles (UAV) and autonomous vehicles, in addition to fixed fiber-based quantum networks.