Full Counting Statistics (FCS) can provide valuable information on manybody systems especially if the underlying correlations cannot be directly imaged. We have used the FCS of Rydberg excitations to gain information on Rydberg interacting manybody systems. We find asymmetric excitation spectra and enhanced fluctuations of the Rydberg atom number which we attribute to the formation of Rydberg aggregates, i.e. correlated systems comprised of few excitations. We conclude that in the presence of dephasing these aggregates are formed via sequential excitation around an initial grain. Our work opens new perspectives for investigating the build-up of correlations in many-body systems.
Phys. Rev. Lett. 112, 013002 (2014)