Dresden 2011 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 20: Quantum Information: Concepts and Methods 3

Q 20.9: Vortrag

Dienstag, 15. März 2011, 12:30–12:45, SCH A118

Permutationally invariant tomography of a four qubit symmetric Dicke state — •Christian Schwemmer1,2, Géza Tóth3,4,5, Witlef Wieczorek6, David Gross7, Roland Krischek1,2, and Harald Weinfurter1,21Max-Planck-Institut für Quantenoptik, D-85748 Garching — 2Fakultät für Physik, Ludwig-Maximilians-Universität, D-80797 München — 3Department of Theoretical Physics, The University of the Basque Country, E-48080 Bilbao — 4IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao — 5Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, H-1525 Budapest — 6Faculty of Physics, University of Vienna, A-1090 Vienna — 7Institute for Theoretical Physics, Leibniz University Hannover, D-30167 Hannover

Multi-partite entangled quantum states play an important role for many quantum information tasks. Therefore, efficient measurement schemes for characterizing these states are needed. As shown by Tóth et al. [1], when restricting to permutationally invariant states the measurement effort scales only quadratically with the number of qubits. Here, we present experimental results of the tomographic analysis of a photonic four qubit Dicke state. Instead of 81 basis settings for full tomography only 15 basis settings have to be measured. We investigate the possibility of permutationally invariant tomography for photonic systems with a larger number of qubits on the example of a six photon symmetric Dicke state. Due to the low count rates for such systems, full tomography is practically impossible.
Tóth et al., Phys. Rev. Lett., in press; talk by Tóth

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