Stuttgart 2012 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
Q: Fachverband Quantenoptik und Photonik
Q 58: Photonik 3
Q 58.6: Talk
Friday, March 16, 2012, 12:00–12:15, V38.01
Four state discrimination via a hybrid receiver — •Christian R. Müller1,2, Mario A. Usuga3,1, Christoffer Wittmann1,3, Masahiro Takeoka4, Christoph Marquardt1,3, Ulrik L. Andersen3,1, and Gerd Leuchs1,3 — 1Max Planck Institute for the Science of Light, Erlangen, Germany — 2Department of Physics, University of Erlangen-Nuremberg, Germany — 3Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark — 4National Institute of Information and Communications Technology, 4-2-1 Nukui-Kita Koganei, Tokyo 184-8795, Japan
According to the basic postulates of quantum mechanics, perfect discrimination of nonorthogonal quantum states is impossible and strict bounds apply for the minimum error rates that can be achieved [1]. Little attention has so far been devoted to the development of discrimination protocols for multi-letter alphabets [2]. We propose and experimentally demonstrate a near optimal hybrid discrimination scheme for the quadrature phase shift keying protocol (QPSK). We show in theory and by means of experimental results that the performance of our scheme is superior to the standard approach - heterodyne detection - for all signal amplitudes. The discrimination is composed of a quadrature measurement, a feed forward and a photon detection.
[1] C. W. Helstrom, Mathematics in Science and Engineering (Academic, New York, 1979), Vol. 123
[2 ]S. Lorenz, N. Korolkova and G. Leuchs, Appl. Phys. B, 79 (3), 273 - 277 (2004)