# A New Playground for Many-Body Physics: Neutral Atoms in an Optical Lattice

## Ken O'Hara

National Institute of Standards and Technology

### Abstract:

Investigations of quantum degenerate atomic gases have primarily focused on weakly-interacting systems which are well described by mean-field theory. I will discuss experiments that begin to explore the strongly-correlated regime by studying atoms confined in an optical lattice potential. Optical lattice potentials, produced by the interference of laser beams, provide highly flexible and precisely controllable periodic confinement for neutral atoms.

The low dimensionality and/or tight confinement realized in an optical lattice can result in a strongly-correlated many-body system. I will describe our investigation of a one dimensional Bose gas which requires a description beyond that which can be provided by mean-field theory. I will also discuss our realization of the 1-D Bose-Hubbard model and our observation of a superfluid-to-Mott insulating transition that exhibits expected as well as unexpected behavior. These and future investigations will help to test the limitations of theoretical techniques developed to treat the many-body problem.