Berlin 2014 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 37: Quantum information: Concepts and methods I
Q 37.4: Talk
Thursday, March 20, 2014, 11:15–11:30, Kinosaal
Detection of multipartite entanglement close to symmetric Dicke states — •Géza Tóth1,2,3, Giuseppe Vitagliano1, Iagoba Apellaniz1, Iñigo L. Egusquiza1, Bernd Lücke4, Jan Peise4, and Carsten Klempt4 — 1Theoretical Physics, University of the Basque Country UPV/EHU, E-48080 Bilbao, Spain — 2IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain — 3Wigner Research Centre for Physics, H-1525 Budapest, Hungary — 4Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, D-30167 Hannover, Germany
We define a new spin squeezing parameter for entanglement detection that, for large particle numbers, is strictly stronger than the original spin squeezing parameter defined in [A. Sorensen et al., Nature 409, 63 (2001)]. For almost fully polarized states and for large particle numbers, the new parameter equals the old one and has a large noise tolerance. Our new parameter detects unpolarized states, such as symmetric Dicke states, that are not detected by the original spin squeezing parameter. We show that the collective quantities necessary to measure the new parameter can also be used to detect multipartite entanglement in the vicinity of symmetric Dicke states, which is very relevant to recent experiments in cold atoms.