APPARATUS FOR FREE-SPACE QUANTUM KEY DISTRIBUTION IN DAYLIGHT

摘要

A quantum cryptography apparatus securely generates a key to be used for secure transmission between a sender (61) and a receiver (65) connected by an atmospheric transmission link (66). A first laser (69) outputs a timing bright light pulse; other lasers (68) output polarized optical data pulses after having been enabled by a random bit generator. Output optics (61)transmit output light (68, 69) from the lasers that is received by receiving optics (65, 71), where a received timing bright light pulse (69) is directed to a delay circuit (74) for establishing a timing window for receiving light from the lasers. A computer (65) receives pulses representing receipt of a timing bright timing pulse (69) and first and second data bit values in accordance with first and second polarization states of the output polarized optical data pulses (68), respectively. The receipt of the first and second data bit values is indexed by the bright timing pulse(69).