Stuttgart 2012 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 54: Poster 3
Q 54.6: Poster
Donnerstag, 15. März 2012, 16:30–19:00, Poster.I+II
Free Space Quantum Communication using Continuous Polarization Variables — •Bettina Heim1,2, Christian Peuntinger1,2, Fabian Sproll1, Christoffer Wittmann1,2, Christoph Marquardt1,2, and Gerd Leuchs1,2 — 1MPI for the Science of Light, Günther-Scharowsky-Str. 1 / Bld. 24, Erlangen — 2Institute of Optics, Information and Photonics, University of Erlangen-Nuremberg, Staudtstraße 7 / B2, 91058 Erlangen, Germany
We present our experimental work on quantum communication using an atmospheric channel of 1.6 km in an urban environment. In our 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 (LO). Both, signal and LO, are sent through the free-space quantum channel, polarization multiplexed and occupying the same spatial mode. This leads to an excellent detection interference and an auto-compensation of the phase fluctuations introduced by the channel. Additionally, the LO automatically acts as a spatial and spectral filter, which allows for unrestrained daylight operation. As low losses are a crucial point for quantum communication protocols, we have developed an active beam stabilization in order to increase the overall channel transmission. Currently, we are working on the implementation of protocols for Continuous Variable (CV) Quantum Key Distribution with different modulation schemes. Furthermore, the transmission of squeezed and EPR-entangled states is in preparation.