High-bandwidth FPGA based randomized voltage states for controlling optoelectronic devices in QKD systems.

We have developed an inexpensive system for generating random voltage states (RVS) on a FPGA platform. This system can be used for controlling optoelectronic devices in a quantum-key-distribution (QKD) system. We use an all-digital operation at the FPGA layer to generate two uncorrelated Boolean bit strings. These bit strings are converted to RVS using a multiplexer and a voltage buffer in order to drive commercially available optoelectronic devices. A National Instruments (N.I) real-time IO (RIO) platform was used for FPGA implementation. The FPGA layer was coupled to the desktop layer for real-time monitoring and logging of the Boolean bit strings. We characterize the performance of the multiplexer and the buffer and describe how their engineering performance trades-off with the fidelity of RVS generation.