Spin Transport in Ultracold Rydberg Atoms

Chih-Chun Chien, Sebastiano Peotta, Massimiliano Di Ventra

Donald P. Fahey, Thomas J. Carroll, Michael W. Noel

The long-range, anisotropic nature of the interaction among atoms in an ultracold dipolar gas leads to a rich array of possibilities for studying many-body physics. In this work, an ultracold gas of highly excited atoms is used to study energy transport due to the long-range dipole-dipole interaction. A technique is developed to measure both the internal energy states of the interacting Rydberg atoms and their positions in space. This technique is demonstrated by observing energy exchange between two spatially separated groups of Rydberg atoms excited to two different internal states. Simulations confirm the general features of the energy transport in this system and highlight subtleties associated with the homogeneity of the electric field used in this experiment.

H. Schempp

This thesis investigates different aspects of strongly interacting ultracold Rydberg gases coupled by light, including the excitation of correlated structures called Rydberg aggregates and dipolar energy transport. For this purpose an experimental apparatus has been constructed. We study coherent population trapping (CPT) and electromagnetically induced transparency (EIT) involving Rydberg states. To study the formation of Rydberg aggregates we use full counting statistics (FCS) which makes it possible to infer the size of Rydberg aggregates. Dephasing during the excitation is found to have a dramatic effect on the formation process, leading to sequential growth around an initial grain. Rydberg state EIT is used to realize a new direct optical imaging scheme for Rydberg atoms which combines highly sensitive detection with high spatial and temporal resolution. Applying this technique we observe dipole-mediated energy transport processes between Rydberg atoms. We study classical transport in the presence of strong measurement induced decoherence. The strong interactions are seen to mediate long-range hopping significantly beyond nearest neighbors. We present first indications for coherent transport in this system. These experiments shed light on the role of correlations in the excitation and evolution of strongly interacting quantum systems and e.g. could possibly be used to model energy transport in biological systems. \n

Sebastian Krinner

Matthias Weidemüller, M. Reetz‐Lamour, Thomas Amthor +3 more

Thomas Niederprüm, Oliver Thomas, Torsten Manthey +2 more

We have studied the associative ionization of a Rydberg atom and a ground-state atom in an ultracold Rydberg gas. The measured scattering cross section is 3 orders of magnitude larger than the geometrical size of the produced molecule. This giant enhancement of the reaction kinetics is due to an efficient directed mass transport which is accelerated by the Rydberg electron. We also find that the total inelastic scattering cross section is given by the geometrical size of the Rydberg electron's wave function.