While several members of the faculty who consider themselves primarily experimentalists occasionally delve into purely theoretical research, there are five members of the faculty whose research has been primarily on the theory side, and all of whom are well known in their respective fields.

Prof. Chan, although directing an experimental group in high-Tc superconductors, conducts research in numerous areas of atomic theory including atomic collisions, two-dimensional atoms, and two-photon processes.

The department is proud to have two leading theorists in the field of quantum optics: Professor Gea-Banacloche and Professor Vyas. Professor Gea-Banacloche's most recent research has been on the quantum suppression of chaos in a system described by the spin-boson Hamiltonian. Other current projects also involve the quantum-classical correspondence, in cavity quantum electrodynamics systems. He anticipates that future research work will involve a look at sources of decoherence in proposed systems for quantum computers.

Prof. Vyas research interests are in the areas of quantum optics, nonlinear optics, and laser physics. She and her students are studying properties of nonclassical states of light generated by nonlinear optical processes such as second-harmonic generation, four-wave mixing and optical parametric oscillations. They are also studying interaction of these nonclassical states with simple atomic systems consisting of two- and three-level atoms. Another area of research interest is quantum effects associated with the motion of atoms trapped in time-dependent fields.

Prof. Harter is interested in the study of molecular spectra using group-theoretical techniques, and has authored a standard textbook in this area. His research has focused on the rotational and vibrational dynamics of molecules and their symmetry properties, including the original theory of superfine and superhyperfine rovibrational spectral structure. This has been applied to studies of molecular species ranging from Freon (CF-4) to (since (1986) ) Buckminsterfullerene (C-60), also known as buckyball. In fact his study of the spectrum of buckyball led to the confirmation of its experimental discovery.

Prof. Lieber is interested in the broad area of mathematical physics, including quantum field theory, but his current research is on nonrelativistic quantum mechanical scattering theory and particularly on three-body problem. Currently he is working on finding an improved wave function for three charged particles, no two of which are bound. This wave-function is important for calculating the cross section for ionization of atoms by impact of charged particles such as protons or electrons. He is the author of the well-known Lieber diagram, (see the Atomic, Molecular and Optical Physics Handbook published by the American Institute of Physics) which determines the kinematic possibility of capture of a particle from a target atom by a projectile.