Free Space Decoy-state Quantum Key Distribution Implementation

AGUSTINA G. MAGNONI; IGNACIO H. LOPEZ GRANDE; MIGUEL A. LAROTONDA

Pucón

Conferencia; IX Reunión Iberoamericana de Óptica y XII Reunión Iberoamericana de Óptica, Láseres y Aplicaciones (RIAO-OPTILAS 2016); 2016

Centro de Óptica y Fotónica de la Universidad de Concepción (CEFOP-UDEC)

In this work we introduce a complete Quantum Key Distribution device that implements a decoy-state protocol [1]. Qubits are codedin the polarization state of weak optical pulses, produced by infrared LEDs [2]. The linkbetweenTransmission (Alice) and Reception (Bob) stages is open air, which is the preferred channel to eventually through low-orbit satellites establish quantumcommunications.Both terminalsare placed on differentrooms, separated byapproximately 8meters.In order to compensate misalignments produced by small mechanic displacements or atmospheric thermal gradients, the system implements a closed-loop for automatic alignment based on a counter-propagating laser, a servo-actuated mirror and a CMOS image sensor. The apparatus runs in an autonomous way,and in the above described conditions it is able to generate raw cryptographic key at a rate of 185 bits/s, with a QBER of6.15%.