Hannover 2010 – wissenschaftliches Programm
Q 17.8: Vortrag
Dienstag, 9. März 2010, 16:15–16:30, E 214
Generation of macroscopic singlet states in atomic ensembles — •Geza Toth1,2,3 and Morgan W. Mitchell4 — 1Theoretical Physics, The University of the Basque Country, E-48080 Bilbao, Spain — 2IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain — 3Research Institute for Solid State Physics and Optics, H-1525 Budapest, Hungary — 4ICFO, Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona), Spain
We study squeezing of the spin uncertainties by quantum non-demolition (QND) measurement in non-polarized spin ensembles. Unlike the case of polarized ensembles, the QND measurements can be performed with negligible back-action, which allows, in principle, perfect spin squeezing as quantified by [G. Toth et al., Phys. Rev. Lett. 99, 250405 (2007)]. The generated spin states approach many-body singlet states, and contain a macroscopic number of entangled particles, even when individual spin is large. We introduce the Gaussian treatment of unpolarized spin states and use it to estimate the achievable spin squeezing for realistic experimental parameters. Our proposal might have applications for quantum memories storing information in decoherence free subspaces.