Spectroscopic Probe of Inhomogeneous Mott Phases

The feasibility of creating a spatially-inhomogeneous phase of neutral bosonic atoms (such as Rubidium) in which multiple Mott-insulating states coexist in a shell structure is discussed and analyzed. In the set-up of trapped, tightly confined bosons in an optical lattice, we derive the conditions on experimental parameters, such as number of bosons and the curvature of the trapping potential, for creating an onion-like structure of any prescribed number of Mott shells with different occupation numbers. We discuss the stability of such a structure with an eye toward experimental conditions necessary for measuring the structure with spectroscopic probes. The analyses ought to give a controlled means of achieving the Mott groundstate observed in previous experiments, and give some constraints for how successfully these states can be employed for quantum computing.