Our research is a balance between theory and experiment in the two areas of optical control of atomic motion and atoms in highly excited states. The theory often predicts new effects that are then studied experimentally, and the laboratory often produces new results that demand more theoretical explanation. Some of the theoretical developments at Stony Brook are unique in the world, and international collaborations have developed on several fronts. Our experiments in laser cooling of rubidium and helium complement one another with quite different values of relevant atomic parameters. Furthermore, our lithium Rydberg atoms will soon be used in atom optics studies providing a third view of optical control of atomic motion.
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Diode lasers play a prominent role in all of our experiments. These highly tunable, ultra low cost light sources have revolutionized experiments in atomic physics, and our group has provided some of the leadership in the area of their development. Certainly their implementation as precisely controllable devices offer challenge and opportunity in optical instrumentation and measurement. The 1993 thesis of Bob Ryan (now at Northrop- Grumman) demonstrated the fundamentally quantum character of the noise from laser diodes.
Optical control of atomic motion is a field of atomic physics that is emerging from laser cooling. It is based in the notion that propagation and interference of deBroglie wave fields provide some fascinating questions about fundamental interactions between atoms and light. The 1995 thesis of Mark Widmer (now at Brookhaven) focused on special atomic states whose wave functions were superpositions of different momenta so that the "parts of the atom" were actually moving in different directions (Schrödinger cat states).
Measured velocity distribution of single atoms showing opposite velocity components
Highly excited states of atoms (Rydberg atoms) display very special properties that are quite different from ordinary states. They can be used for extremely precise electric field measurements or as probes for tiny field inhomogeneities. In 1995 Jerry Stevens and a post-doc working together completed the most precise Stark spectroscopy ever, for the first time putting electric fields on a par with magnetic fields in terms of precision measurement. Up to now, there has never been a completely atomic standard for electric fields comparable to NMR for magnetic fields.
Coulomb potential distorted by an applied dc electric field
On the theoretical side, the advent of deBroglie wave optics, which is the quantum view of atomic motion, has stimulated our use of a density matrix that includes the atomic KE. It has been generalized to allow careful modeling of experimental details that allow superb prediction and corroboration of measurements. It is complemented by an analytic approach that includes the KE directly in the Hamiltonian. The 1995 thesis of Marya Doery (now at Eindhoven) presented solutions that provided valuable insight into laser-atom interactions, as well as quantitative results that were compared with data. By contrast, the 1995 thesis of Chuan Xie (now at Caltech) provided a blueprint for future study in the semi-classical domain of atomic motion. On another topic, Tom Bergeman has extended an existing R-matrix technique for high precision comparison between our Stark spectra from Rydberg atoms with direct solutions of the Schroedinger equation. This will form the basis of another thesis. Finally, we are beginning to study some interesting questions about Bose condensates, in particular, the nature of certain collective excitations.
Undergraduates John Sugrim and Ray Fliller, together with graduate student Mark Widmer (now at Brookhaven) and Prof. Metcalf.
Mary-Jo Bellanca (Jo.Bellanca@uni-konstanz.de), Felix Chi (fchi@ic.sunysb.edu), Jerry Stevens, Liang Liu (lliu@lightpath.com), Marty Williams (martysandy@stny.rr.com), Marya Doery (M.R.Doery@phys.tue.nl), Rajeev Gupta (gupta@epg.nist.gov), Sebastian Padua (spadua@fisica.ufmg.br), Bob Ryan (RRyan60599@aol.com), Chuan Xie (cxie@sunoptics.caltech.edu), and Mark Widmer (widmer@nuclear.physics.sunysb.edu)
Group Director: Prof. Harold Metcalf, (631) 632-8185, (631) 632-8176 (FAX) (e-mail)
Research Professor: Dr. Tom Bergeman, (631) 632-8186, (631) 632-8176 (FAX) (e-mail)
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