probing electron-electron and atom-atom interactions using Rydberg atoms
Dunning, Frank Barry
Doctor of Philosophy
Highly excited Rydberg states, neutral atomic states with one or more electrons promoted to states of large principal quantum number n are now commonly used for producing quantum entanglement. This is facilitated through the "Rydberg Blockade" effect where the presence of a single Rydberg atom blocks excitation of further atoms in a surrounding mesoscopic volume due to strong atom-atom interactions induced by the large dipole moments associated with Rydberg atoms. In this work, we report the first observation of this phenomenon in a hot atomic beam using very high n, n ~300 - 500, strontium nF Rydberg states. Inside the blockaded volume (size around 0.1mm), the Rydberg number distribution is sub-Poissonian. However, as predicted by theoretical calculations, due to the anisotropic nature of the atom-atom interactions, the blockade is incomplete. However, the blockade effect is sufficiently strong to enable detailed study of few-body atom-atom interactions and of entanglement. Doubly-excited Rydberg states having a pair of electrons excited to high lying energy levels are typically difficult to create and are short lived because of "autoionization" resulting from electron-electron scattering. Strontium Rydberg atoms are used to study this scattering and we demonstrate an efficient mechanism to eliminate "autoionization" pointing to the production of long-lived strongly correlated two-electron-excited atomic states.
strontium; Rydberg blockade; doubly-excited state; autoionization