Berlin 2014 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 59: Quantum information: Quantum computers and communication I
Q 59.1: Vortrag
Freitag, 21. März 2014, 10:30–10:45, DO26 207
Verification of Effective Entanglement over an Atmospheric Channel — •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 1.6km 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. We investigate the verification of effective entanglement within the framework of a protocol for continuous variable quantum key distribution (CV-QKD) with a discrete modulation of four signal states. In addition, by again taking into account the fading channel properties, we study a method of probabilistic CV-QKD.