Quantum Information Exchange Between Photons and Atoms

Abstract

This thesis contains two parts. In Part I, we study the atom-pulse interaction for Fock state and coherent state pulses. The effect of pulses temporal and spectral properties on atomic excitation is studied for both single-photon and multi-photon cases. The theoretical prediction is compared with an experiment, where a single rubidium atom interacts with temporally shaped coherent state pulses. Next, we propose a quantum memory based on a two-level atom in a half cavity. We show that various temporal shapes of incident photon can be stored and read out efficiently by an appropriate motion of the mirror. In Part II, we propose an ultrafast quantum controlled-phase gate scheme, which includes a suitable qubit-resonator ultrastrong interacting architecture and a gate operating on a time scale proportional to the inverse of the resonator frequency. Numerical simulation shows that this quantum gate can perform on sub-nanosecond time scales while keeping fidelity above 99.5%.