1303.1230 (M. L. Wall et al.)

Confinement modifies interactions of ultracold dipolar gases on optical
lattices    [PDF]

M. L. Wall, L. D. Carr

We study the effective dipole-dipole interactions in ultracold quantum gases on optical lattices as a function of imbalance in confinement along the principal axes of the lattice. We demonstrate that the effective dipole-dipole interaction in the lattice decays exponentially with the inter-particle separation at short to medium distance on the lattice scale and has a long-range power-law tail, in contrast to the pure power-law behavior of the dipole-dipole interaction in free space. The effect can be sizable; we identify differences of up to 36% from the free-space interaction at the nearest-neighbor distance in quasi-1D arrangements. The modified interaction arises from quantum fluctuations induced by heavy tails of the localized single-particle probability distributions, and also relies crucially on imbalance in confinement, due to the d-wave anisotropy of the dipole-dipole interaction. Using matrix product state simulations, we demonstrate that use of the correct lattice dipolar interaction leads to significant deviations from many-body predictions using the free-space interaction in the lattice. Our results are relevant to up and coming experiments with heteronuclear molecules, Rydberg atoms, and strongly magnetic atoms in optical lattices.

View original: http://arxiv.org/abs/1303.1230