Stuttgart 2012 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 8: Quanteninformation: Konzepte und Methoden 2
Q 8.7: Talk
Monday, March 12, 2012, 15:30–15:45, V38.04
Permutationally Invariant Tomography of a Six Qubit Symmetric Dicke State — •Christian Schwemmer1,2, Géza Tóth3,4,5, Alexander Niggebaum1,2, Tobias Moroder6, Philipp Hyllus3, Otfried Gühne6,7, and Harald Weinfurter1,2 — 1MPI 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 — 6Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, A-6020 Insbruck — 7Naturwissenschaftlich-Technische Fakultät, Universität Siegen, D-57072 Siegen,
Multi-partite entangled quantum states are promising candidates for potential applications like quantum metrology or quantum communication. Yet, efficient tools are needed to characterize these states and to evaluate their applicability. Standard quantum state tomography suffers from an exponential increase in the measurement effort with the number of qubits. Here, we show that by restricting to permutational invariant states like GHZ, W or symmetric Dicke states the problem can be recast such that the measurement effort scales only quadratically [1]. We apply this method to experimentally analyze a six photon symmetric Dicke state generated by parametric down conversion where instead of 729 only 28 basis settings have to be measured.
Tóth et al., Phys. Rev. Lett. 105, 250403 (2010)