Hannover 2013 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 43: Poster II
Q 43.77: Poster
Mittwoch, 20. März 2013, 16:00–18:30, Empore Lichthof
Free Space Quantum Communication using Continuous Polarization Variables — •Bettina Heim1,2, Christian Peuntinger1,2, Christoffer Wittmann1,2, Christoph Marquardt1,2, and Gerd Leuchs1,2 — 1MPI for the Science of Light, Günther-Scharowsky-Str. 1 / bldg. 24, Erlangen — 2Institute of Optics, Information and Photonics, University of Erlangen-Nuremberg, Staudtstraße 7 / B2, Erlangen
We present our experimental work on quantum communication using an atmospheric channel of 1.6 km in an urban environment. In a prepare-and-measure setup, we encode information into continuous polarization states. The signal states are measured using homodyne detection with the help of a local oscillator. Both, signal and local oscillator, are sent through the free-space quantum channel, polarization multiplexed and occupying the same spatial mode. This leads to an excellent interference at the detection and an auto-compensation of the phase fluctuations introduced by the channel. In addition, the local oscillator acts as a spatial and spectral filter which easily enables daylight operation. Currently, we are testing a protocol for continuous variable quantum key distribution (CVQKD) with discrete modulation of four signal states in terms of the channel’s key properties, attenuation and excess noise. Those turned out to be low enough to pave the way towards free space CVQKD.