Abstract

We describe experiments in which circular Rydberg atoms interact one at a time in a high Q microwave cavity with small fields made of a few photons. Resonant and dispersive atom-field couplings produce various forms of controlable matter-radiation entanglement. Quantum non demolition measurement of single photons, quantum phase gates, multi-atom entanglement and decoherence studies are realized with this system. As a simple illustration of the concept of complementarity, we have also performed an atomic interferometry experiment in which the cavity field acts as a "quantum beam splitter" storing which-path information. The relevance of all these experiments for quantum information processing.

© 2001 Optical Society of America