A Prototype for Quantum Key Distribution

IGNACIO LÓPEZ GRANDE

Paraty

Workshop; IV Quantum Information School and Workshop - Paraty 2013; 2013

We present a practical photonic implementation of the BB84 protocol of Quantum Key Distribution (QKD), with sturdiness, simplicity and resource-efficiency of the design as main objectives. The scheme is based on faint pulses of different polarizations generated through four infrared LEDs with their optic paths multiplexed. The basis selection in the detection side is made in a passive manner with a beamsplitter, and the four possible outcomes are detected with an only single-photon-counter and a time-multiplexing scheme based on optical fiber. The system includes the synchronization between the sender and the receiver, a classical communication channel and an asynchronous transmission scheme. The control of the protocol, as well as the final processing to sift the distributed key are accomplished in each of the two stations by the open-source based microcontrollers Arduino. In this first test of the complete system we achieve a sifted key rate of 365bps handed over to a PC on each station. This system was thought as a starting point for other experiments of practical and academical interest, such as high speed QKD on optical fiber-based systems and QKD with tomographic security.