Heidelberg 2015 – wissenschaftliches Programm
Q 31.36: Poster
Dienstag, 24. März 2015, 17:00–19:00, C/Foyer
Efficient State Analysis and Entanglement Detection — •Christian Schwemmer1,2, Lukas Knips1,2, Geza Toth3,4,5, Tobias Moroder6, Matthias Kleinmann3, David Gross7, Otfried Gühne6, and Harald Weinfurter1,2 — 1Department für Physik, LMU, D-80797 München — 2MPI für Quantenoptik, D-85748 Garching — 3Department of Theoretical Physics, University of the Basque Country UPV/EHU, E-48080 Bilbao — 4IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao — 5Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest — 6Naturwissenschaftlich-Technische Fakultät, Universität Siegen, D-57068 Siegen — 7Physikalisches Institut, Universität Freiburg, D-79104 Freiburg
Multipartite entanglement lies at the very heart of quantum mechanics and offers many fascinating applications like, e.g., quantum computing or quantum metrology. Hence, experimentally friendly tools for fast entanglement detection and characterization with better than exponential scaling are needed. Here, we implement such an efficient scheme, tomography in the permutationally invariant subspace, and compare its performance against compressed sensing tomography and standard tomography for a six-photon symmetric Dicke state. For data processing, we developed a scalable fitting algorithm based on convex optimization. By means of this algorithm, we were also able to study systematic deviations of the maximum likelihood estimation for fidelity and negativity, which for finite statistics get (strongly) biased for constrained optimization.