Excitation and Control of Cold Rydberg Gases

The spatial extend of highly excited Rydberg atoms exceeds the size of ground-state atoms by orders of magnitudes. Such large excursions of the Rydberg electron imply very long lifetimes, high susceptibilities to external fields and strong interactions between the atoms. In addition, the low temperatures, achievable in laser-cooled gases, render thermal motion negligible on all relevant timescales. Such "frozen" Rydberg gases, hence, behave very much like an amorphous solid rather than a gas, with its dynamics solely governed by the strong Rydberg-Rydberg atom interactions.

 Already the mere preparation of such gases is very different from laser-excitation to low-lying states, showing, e.g., strong interaction-induced suppression of Rydberg population. As one intriguing application, the extreme case of a fully blockaded sample has been proposed as a mesoscopic device for storage and fast manipulation of quantum information.

In this project we are interested in the dynamics of the Rydberg excitation process as well as the successional gas evolution induced by the strong atomic interactions. We are developing specifically designed computational tools and simplified analytical pictures to master the generally challenging task of describing quantum many-body systems. Beyond uncovering generic features of the multifarious dynamics of cold Rydberg gases, we, for example, explore the utility of external fields to manipulate their evolution, engineer interactions and produce desired quantum states in a controlled fashion. 

Time evolution of the two.particle Ryberg atom density in a small, laster-driven cloud of atoms. Strong interactions between Ryberg atoms lead to pronounced anti-correlations and blocking of further excitations.