Laser autocalibration for QKD systems

Abstract

A method of autocalibrating a quantum key distribution (QKD) system (200) is disclosed. The QKD system includes a laser ((202) that generates photon signals in response to a laser gating signal (S0) from a controller (248). The method includes first performing a laser gate scan (304) to establish the optimum arrival time (TMAX) of the laser gating signal corresponding to an optimum-e.g., a maximum number of photon counts (NMAX)-from a single-photon detector (SPD) unit (216) in the QKD system when exchanging photon signals between encoding stations (Alice and Bob) of the QKD system. Once the optimal laser gating signal arrival time (TMAX) is determined, the laser gate scan is terminated and a laser gate dither process (308) is initiated. The laser dither involves varying the arrival time (T) of the laser gating signal around the optimum value of the arrival time TMAX. The laser gate dither provides minor adjustments to the laser gating signal arrival time to ensure that the SPD unit produces an optimum (e.g., maximum) number of photon counts.

Description

[0001] claim priority [0002] This application claims priority to US Provisional Patent Application 60 / 554,687, filed March 19,2004. technical field [0003] The present invention relates to the technical field of quantum encryption, and has industrial applicability in the field of quantum encryption, more specifically, relates to a device and a method for automatically calibrating a quantum key distribution (QKD) system to maintain the best system performance, and has the same characteristics as the automatic calibrating Quantum key distribution (QKD) systems with associated industrial applicability of apparatus and methods for maintaining optimal system performance. Background technique [0004] Quantum key distribution (QKD) involves using a weak (e.g. average 0.1 photon (photon)) optical signal ("photon signal") sent over a "quantum channel" ”) to establish a key between. The security of key distribution is based on the quantum mechanism principle that any measurement...

AI Technical Summary

Problems solved by technology

However, once the system is set up, timing drifts due to various system factors and environmental factors, and photon counts may drop

This results in a reduction in the transmission rate of the system and results in an increased bit error rate (i.e. less than optimal system performance)

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