Strongly correlated excitation of a quasi-1D Rydberg gas

Rydberg excitation dynamics of a 87-Rb cold atom cloud is investigated in an effective one-dimensional geometry. We measure the excitation dynamics and the full counting statistics for resonant and off-resonant excitation to the 70 S state. While for a resonant laser excitation the counting distributions have a strong sub-Poissonian character, we find strongly bimodal counting distributions in the off-resonant regime. The n-th central moments, up to n = 4, of the counting distributions are derived from the measured counting distributions.