Weak Coherent Pulse Source and Polarization Control for Quantum Key Distribution

Abstract

The Quantum EncrYption and Science Satellite will demonstrate quantum communication from space. One demonstration will be a satellite uplink using a weak coherent pulse source. This thesis will discuss work in minimizing the quantum bit error rate of polarization-encoded states produced by the weak coherent pulse source, including a wave packet model developed to quantify fiber length and angular alignment tolerances within the system. In addition, the weak coherent pulse sources makes use of polarization-maintaining fibers, requiring a polarization control system to compensate for phase shifts induced in the fiber during operation of the quantum uplink. Methods for polarization control in polarization-maintaining fiber are explored and compared.