Dresden 2011 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 28: Quantum Information: Quantum Communication 1
Q 28.3: Vortrag
Mittwoch, 16. März 2011, 11:00–11:15, SCH A01
Daylight Free Space Quantum Communication using Continuous Polarization Variables — •Christian Peuntinger1,2, Bettina Heim1,2, Christoffer Wittmann1,2, Christoph Marquardt1,2, and Gerd Leuchs1,2 — 1Max-Planck-Institut für die Physik des Lichts, Günther-Scharowsky-Str. 1 / Bau 24, 91058 Erlangen, Deutschland — 2Institut für Optik, Information und Photonik, Universität Erlangen-Nürnberg, Staudtstrasse 7 / B2, 91058 Erlangen, Deutschland
We present our experimental work on quantum communication using a free space quantum channel of 1.6km in an urban environment. In our prepare-and-measure setup, we perform binary encoding of 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 channel while occupying the same spatial mode. This leads to excellent interference at the detection and an auto-compensation of the phase fluctuations introduced by the channel. Additionally the LO automatically acts as a spatial and spectral filter of the signal, which allows for unrestrained daylight operation. We have compared Stokes measurements on the quantum states before and after passing the free space channel using different modulation patterns. This allows for investigation of the influences of the turbulent atmosphere on our quantum states. A main drawback when working with an atmospheric channel is spatial beam jitter. We studied these kind of effects in detail and will present methods to reduce their impact.