Freiburg 2019 – wissenschaftliches Programm
FM 74.3: Talk
Donnerstag, 26. September 2019, 14:45–15:00, 1009
Quantum key distribution with a hand-held sender unit — Gwenaelle Vest1, •Peter Freiwang1, Jannik Luhn1, Tobias Vogl2, Markus Rau1, Wenjamin Rosenfeld1, and Harald Weinfurter1, 3 — 1Ludwig Maximilian Universtity (LMU), Munich, Germany — 2Australian National University (ANU), Canberra, Australia — 3Max Planck Institute of Quantum Optics (MPQ), Garching, Germany
QKD enables secure communication by detecting eavesdropping attacks. While impressive progress was made in the field of long-distance implementations, user-oriented applications involving short-distance links have mostly remained overlooked. In this work we report on a hand-held free-space QKD system including a micro-optics based sender unit. This system implements a BB84-protocol employing polarization encoded faint laser pulses at a rate of 100 MHz. Unidirectional beam tracking and live reference-frame alignment systems at the receiver side enabled a stable operation over tens of seconds when holding the portable transmitter at a distance of 30 cm. Successful key exchange was performed by different untrained users with an average link efficiency of about 20 % relative to the case of the transmitter being stationary mounted and aligned with key rates ranging from 4.0 kbps to 15.3 kbps at an average QBER of 2.4 %. Given its compactness, this versatile sender unit is also well suited for integration into free-space communication systems for urban or even satellite applications.