Tobias Graß, Bruno Juliá-Díaz, Maciej Lewenstein
Existing techniques for synthesizing gauge fields are able to bring a two-dimensional cloud of harmonically trapped bosonic atoms into a regime where the occupied single-particle states are restricted to the lowest Landau level (LLL). Repulsive short-range interactions drive various transitions from fully condensed into strongly correlated states. In these different phases we study the response of the system to quasihole excitations induced by a laser beam. We find that in the Laughlin state the quasihole performs a coherent constant rotation around the center, ensuring conservation of angular momentum. This is distinct to any other regime with higher density, where the quasihole is found to decay. At a characteristic time, the decay process is reversed, and revivals of the quasihole can be observed in the density. Measuring the period and position of the revival can be used as a spectroscopic tool to identify the strongly correlated phases in systems with a finite number of atoms.
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http://arxiv.org/abs/1210.2898
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