TY - JOUR
T1 - Multiple scattering dynamics of fermions at an isolated p-wave resonance
JF - Nature Communications
Y1 - 2016
A1 - Ryan Thomas
A1 - Kris O. Roberts
A1 - Eite Tiesinga
A1 - Andrew C.J. Wade
A1 - P. Blair Blakie
A1 - Amita B. Deb
A1 - Niels Kjærgaard
AB - 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.

VL - 7
U4 - 12069
UR - http://www.nature.com/articles/ncomms12069
U5 - 10.1038/ncomms12069
ER -
TY - JOUR
T1 - Bragg Spectroscopy of ultracold atoms loaded in an optical lattice
JF - Physical Review A
Y1 - 2005
A1 - Ana Maria Rey
A1 - P. Blair Blakie
A1 - Guido Pupillo
A1 - Carl J. Williams
A1 - Charles W. Clark
AB - 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.
VL - 72
UR - http://arxiv.org/abs/cond-mat/0406552v2
CP - 2
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.72.023407
ER -