Colloquium
January 28, 2005

G. S. Agarwal
Nobel Foundation Chair and Professor,
Department of Physics, Oklahoma State University

Inter-Atom Two Photon Processes

We discuss how quantum interferences lead to no inter-atom two photon absorption in coherent fields. Such an absorption can be produced by finding physical mechanisms which would either inhibit the interfering pathways or make the interfering quantum amplitudes asymmetric. Several such mechanisms have now been discovered, and these include excitation by entangled fields, strong dipole-dipole coupling between atoms, and excitation in a high quality cavity. We discuss methods to restore inter-atom two-photon absorption and some recent experiments.

Dr. Agarwal, Nobel Foundation Chair and Professor, Department of Physics, Oklahoma State University, has made extensive contributions in the areas of quantum optics, resonance fluorescence, cavity quantum electrodynamics, quantum control and quantum information. He has been instrumental in starting quantum optical work in several areas and has authored more than 200 papers and a widely quoted research monograph "Quantum Statistical Theories of Spontaneous Emission and Their Relation to Other Approaches."

Prof. Agarwal obtained his Ph.D. in 1969 from the University of Rochester (USA). His contributions have been recognized by election to fellowship in professional societies and numerous national and international awards including Max Born Award (Optical Society of America), Einstein Professor (Indian National Academy of Sciences), Einstein Medal (International Commission on Optics), and Humboldt Foundation Award (Alexander von Humboldt Foundation, Germany).