Stuttgart 2012 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 24: Quanteninformation: Repeater und Speicher
Q 24.3: Vortrag
Dienstag, 13. März 2012, 11:15–11:30, V7.02
Long distance continuous-variable quantum communication — •Imran Khan1,2, Christoffer Wittmann1,2, Nitin Jain1,2, Nathan Killoran3, Norbert Lütkenhaus3, Christoph Marquardt1,2, and Gerd Leuchs1,2 — 1Max-Planck-Institut für die Physik des Lichts, Erlangen — 2Institut für Optik, Information und Photonik, Universität Erlangen-Nürnberg, Erlangen — 3Institute of Quantum Computing, Waterloo CA
Quantum correlations are at the heart of all quantum communication. In experimental data, such correlations can be investigated using the concept of effective entanglement [1, 2]. In a former experiment, we have witnessed the distribution of effective entanglement over a 2 km fiber channel [3]. We now present our results on the quantification of effective entanglement over a 40 km fiber channel. This long distance sets, to our knowledge, a new record for continuous-variable quantum communication.
In our system, non-orthogonal quantum states are sent through a fiber-based quantum channel. The signal is detected using simultaneous homodyne detection of conjugate quadratures. By analyzing the excess noise and the received signal amplitudes , we are able to estimate the amount of distributed effective entanglement [4], which provides insight into the limits of our experimental setup.
[1] J. Rigas et al., Phys. Rev. A 73, 012341 (2006) [2] H. Häseler et al., Phys. Rev. A 77, 032303 (2008) [3] C. Wittmann et al., Opt. Express 18, 4499 (2010) [4] N. Killoran et al., Phys. Rev. A 83, 052320 (2011)