



01556nas a2200217   4500008004100000245006300041210006300104260001500167300001100182490000800193520094300201100002401144700001601168700001801184700001901202700001801221700002501239700002001264700001801284856003601302       2016                        eng d00aAnomalous broadening in driven dissipative Rydberg systems0 aAnomalous broadening in driven dissipative Rydberg systems  c2016/03/16  a1130010 v1163 aWe observe interaction-induced broadening of the two-photon 5s-18s transition in 87Rb atoms trapped in a 3D optical lattice. The measured linewidth increases by nearly two orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18s atoms with spontaneously created populations of nearby np states. Over a range of initial atomic densities and excitation strengths, the transition width is described by a single function of the steady-state density of Rydberg atoms, and the observed resonant excitation rate corresponds to that of a two-level system with the measured, rather than natural, linewidth. The broadening mechanism observed here is likely to have negative implications for many proposals with coherently interacting Rydberg atoms.1 aGoldschmidt, E., A.1 aBoulier, T.1 aBrown, R., C.1 aKoller, S., B.1 aYoung, J., T.1 aGorshkov, Alexey, V.1 aRolston, S., L.1 aPorto, J., V.  uhttp://arxiv.org/abs/1510.0871001656nas a2200193   4500008004100000245007500041210006900116260001500185300001400200490000800214520108600222100001801308700001501326700001901341700002401360700002301384700001801407856003701425       2015                        eng d00a2D Superexchange mediated magnetization dynamics in an optical lattice0 a2D Superexchange mediated magnetization dynamics in an optical l  c2015/04/30  a540 - 5440 v3483 a  The competition of magnetic exchange interactions and tunneling underlies
many complex quantum phenomena observed in real materials. We study
non-equilibrium magnetization dynamics in an extended 2D system by loading
effective spin-1/2 bosons into a spin-dependent optical lattice, and we use the
lattice to separately control the resonance conditions for tunneling and
superexchange. After preparing a non-equilibrium anti-ferromagnetically ordered
state, we observe relaxation dynamics governed by two well-separated rates,
which scale with the underlying Hamiltonian parameters associated with
superexchange and tunneling. Remarkably, with tunneling off-resonantly
suppressed, we are able to observe superexchange dominated dynamics over two
orders of magnitude in magnetic coupling strength, despite the presence of
vacancies. In this regime, the measured timescales are in agreement with simple
theoretical estimates, but the detailed dynamics of this 2D, strongly
correlated, and far-from-equilibrium quantum system remain out of reach of
current computational techniques.
1 aBrown, R., C.1 aWyllie, R.1 aKoller, S., B.1 aGoldschmidt, E., A.1 aFoss-Feig, Michael1 aPorto, J., V.  uhttp://arxiv.org/abs/1411.7036v1