Title:  Ultracold Atoms in Ring Lattices

Speaker:  Kunal K. Das, Professor at Kutztown University of Pennsylvania

Abstract
With two different kinds of periodicities a toroidal or ring-shaped lattice trap introduces new possibilities for ultracold atoms, we will consider some of those here:

Counter-circulating modes of a Bose-Einstein condensate (BEC) in such a trap demonstrate nonlinear criticality with self-trapping and oscillatory regimes, which in the mean-field picture sharply enhances sensitivity to rotation. Quantum fluctuations also however increase near criticality, and we suggest ways to suppress them in the relevant quadrature, by utilizing spin-squeezing.

When the nonlinearity is modulated at half the lattice constant, variation of the amplitude and phase of the modulation accesses various spin squeezing regimes, particularly both one-axis twisting and the elusive two-axes counter-twisting, and generally enables comprehensive realization of the broadly relevant Lipkin-Meshkov-Glick model.

We will also outline how ring topology can be used to implement gauge structures and features related to geometric phase.