%0 Journal Article
%J Nature Communications
%D 2016
%T Multiple scattering dynamics of fermions at an isolated p-wave resonance
%A Ryan Thomas
%A Kris O. Roberts
%A Eite Tiesinga
%A Andrew C.J. Wade
%A P. Blair Blakie
%A Amita B. Deb
%A Niels Kjærgaard
%X The wavefunction for indistinguishable fermions is anti-symmetric under particle exchange, which directly leads to the Pauli exclusion principle, and hence underlies the structure of atoms and the properties of almost all materials. In the dynamics of collisions between two indistinguishable fermions this requirement strictly prohibits scattering into 90 degree angles. Here we experimentally investigate the collisions of ultracold clouds fermionic 40K atoms by directly measuring scattering distributions. With increasing collision energy we identify the Wigner threshold for p-wave scattering with its tell-tale dumb-bell shape and no 90∘ yield. Above this threshold effects of multiple scattering become manifest as deviations from the underlying binary p-wave shape, adding particles either isotropically or axially. A shape resonance for 40K facilitates the separate observation of these two processes. The isotropically enhanced multiple scattering mode is a generic p-wave threshold phenomenon, while the axially enhanced mode should occur in any colliding particle system with an elastic scattering resonance.

%B Nature Communications
%V 7
%P 12069
%8 2016/07/11
%G eng
%U http://www.nature.com/articles/ncomms12069
%R 10.1038/ncomms12069
%0 Journal Article
%J Physical Review A
%D 2005
%T Bragg Spectroscopy of ultracold atoms loaded in an optical lattice
%A Ana Maria Rey
%A P. Blair Blakie
%A Guido Pupillo
%A Carl J. Williams
%A Charles W. Clark
%X We study Bragg spectroscopy of ultra-cold atoms in one-dimensional optical lattices as a method for probing the excitation spectrum in the Mott insulator phase, in particular the one particle-hole excitation band. Within the framework of perturbation theory we obtain an analytical expression for the dynamic structure factor $S(q,\omega)$ and use it to calculate the imparted energy which has shown to be a relevant observable in recent experiments. We test the accuracy of our approximations by comparing them with numerically exact solutions of the Bose-Hubbard model in restricted cases and establish the limits of validity of our linear response analysis. Finally we show that when the system is deep in the Mott insulator regime, its response to the Bragg perturbation is temperature dependent. We suggest that this dependence might be used as a tool to probe temperatures of order of the Mott gap.
%B Physical Review A
%V 72
%8 2005/8/12
%G eng
%U http://arxiv.org/abs/cond-mat/0406552v2
%N 2
%! Phys. Rev. A
%R 10.1103/PhysRevA.72.023407