Many-body Rabi oscillations of Rydberg excitation in small mesoscopic samples

We investigate collective aspects of Rydberg excitations in ultracold mesoscopic samples. Strong interactions between Rydberg atoms influence the excitation process and impose correlations between excited atoms. The manifestations of the collective behavior of Rydberg excitations are many-body Rabi oscillations, spatial correlations between atoms, as well as fluctuations in the number of excited atoms. We study these phenomena in detail by numerically solving the many-body Schrodinger equation, using a superatom approach. We find that, under certain conditions, these many-body behaviors could be observed experimentally.