Ultrafast Laser Studies of Molecular Rydberg Wave Packets

Abstract

Abstract : The goal of this work is to investigate the formation and detection of Rydberg wave packets in molecules and to explore their possible use in quantum information processing. Very few coherent superpositions of molecular Rydberg states have been experimentally realized. Therefore, this research focuses on several new ways to produce coherent superpositions of Rydberg states in molecules as well as innovative methods to detect them by kinetic-energy resolved electron detection and photoelectron angular imaging. Two methods of preparation are developed: (1) pumping through intermediate launch states, and (2) simultaneous three-photon excitation. A number of important proofs of principle were carried out on atoms and then transferred to molecules. The culmination of this work is the observation of a pair of Rydberg states that exhibits entanglement between the core electron angular momentum and the Rydberg electron angular momentum as the Rydberg wave packet oscillates, causing the inner core angular momentum to follow the wave packet motion because of the entanglement. The most important results of the study are as follows: (1) Rydberg wave packets were achieved in Krypton atoms and CO and lithium dimer molecules, (2) laser Stark field shifting of the states in the preparation of Rydberg wave packets by intense laser pulses was studied, (3) predissociation and auto-ionization of CO was investigated, (4) velocity map imaging of the angular distribution of photoelectrons was observed in time-dependent wave packets for the first time, and (5) entanglement of the core angular momentum and the outer electron angular momentum was determined.