Heidelberg 2015 – wissenschaftliches Programm
Q 26.6: Vortrag
Dienstag, 24. März 2015, 15:45–16:00, K/HS1
Generalized spin squeezing in the vicinity of Dicke states — •Giuseppe Vitagliano1, Iagoba Apellaniz1, Iñigo Egusquiza1, Geza Toth1,2,3, Bernd Lucke4, 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 fur Quantenoptik, Leibniz Universitat Hannover, Welfengarten 1, D-30167 Hannover, Germany
We study the problem of detecting entanglement and its depth in systems composed of very many particles. We derive entanglement criteria based only on few easy measurable quantities such as the mean values and variances of collective spin components. In particular we present what we call a generalized spin squeezing parameter, that can be used to detect a class of states wider than the spin squeezed states as defined in [A. Sorensen et al., Nature 409, 63 (2001)]. Moreover we present a criterion to estimate the entanglement depth that outperforms previous well-known criteria. It has been used in a recent experiment [B. Lucke et al., PRL 112, 155304 (Editor's suggestion)] to prove that the produced Dicke-like state had an entanglement depth of at least 28 particles.