%0 Journal Article
%J Physical Review A
%D 2016
%T Photoassociation of spin polarized Chromium
%A Jahn Rührig
%A Tobias Bäuerle
%A Paul S. Julienne
%A Eite Tiesinga
%A Tilman Pfau
%X We report the homonuclear photoassociation (PA) of ultracold 52Cr atoms in an optical dipole trap. This constitutes the first measurement of PA in an element with total electron spin S~>1. Although Cr, with its 7S3 ground and 7P4,3,2 excited states, is expected to have a complicated PA spectrum we show that a spin polarized cloud exhibits a remarkably simple PA spectrum when circularly polarized light is applied. Over a scan range of 20 GHz below the 7P3 asymptote we observe two distinct vibrational series each following a LeRoy-Bernstein law for a C3/R3 potential with excellent agreement. We determine the C3 coefficients of the Hund's case c) relativistic adiabatic potentials to be -1.83±0.02 a.u. and -1.46±0.01a.u.. Theoretical non-rotating Movre-Pichler calculations enable a first assignment of the series to Ω=6u and 5g potential energy curves. In a different set of experiments we disturb the selection rules by a transverse magnetic field which leads to additional PA series.
%B Physical Review A
%V 93
%P 021406
%8 2016/02/29
%G eng
%U http://arxiv.org/abs/1512.04378
%N 2
%R 10.1103/PhysRevA.93.021406
%0 Journal Article
%J Physical Review A
%D 2014
%T Quantum correlations and entanglement in far-from-equilibrium spin systems
%A Kaden R. A. Hazzard
%A Mauritz van den Worm
%A Michael Foss-Feig
%A Salvatore R. Manmana
%A Emanuele Dalla Torre
%A Tilman Pfau
%A Michael Kastner
%A Ana Maria Rey
%X By applying complementary analytic and numerical methods, we investigate the dynamics of spin-$1/2$ XXZ models with variable-range interactions in arbitrary dimensions. The dynamics we consider is initiated from uncorrelated states that are easily prepared in experiments, and can be equivalently viewed as either Ramsey spectroscopy or a quantum quench. Our primary focus is the dynamical emergence of correlations and entanglement in these far-from-equilibrium interacting quantum systems: we characterize these correlations by the entanglement entropy, concurrence, and squeezing, which are inequivalent measures of entanglement corresponding to different quantum resources. In one spatial dimension, we show that the time evolution of correlation functions manifests a non-perturbative dynamic singularity. This singularity is characterized by a universal power-law exponent that is insensitive to small perturbations. Explicit realizations of these models in current experiments using polar molecules, trapped ions, Rydberg atoms, magnetic atoms, and alkaline-earth and alkali atoms in optical lattices, along with the relative merits and limitations of these different systems, are discussed.
%B Physical Review A
%V 90
%8 2014/12/15
%G eng
%U http://arxiv.org/abs/1406.0937v1
%N 6
%! Phys. Rev. A
%R 10.1103/PhysRevA.90.063622