The main thrust of my group's experimental activity involves the manipulation of cold atoms with laser light. Although laser light is a very concentrated source of energy, it has been found, for example, that it can be used to cool atoms to extremely low temperatures on the order of a few micro Kelvin, and optically trap them in a very small volume. Recently there has been increasing activity in using laser light to manipulate atoms in much the same way that light itself is manipulated with lenses, mirrors, and other optical elements. The goal of our research is to develop new techniques to produce small scale atomic structures, as well as to study new fundamental effects involving the quantum mechanical nature of the atomic center-of-mass. Most of our experiments use Rb atoms that are first cooled to sub-millikelvin temperatures and trapped in a small volume (~1mm) with laser light.
As an example of our research activity, we have recently obtained results in which we have exploited the wave nature of matter (the fact that, in a certain sense, an atom can be in two places at once) to produce variations in atomic density with a period that is much less than an optical wavelength. These variations (or "gratings") were produced by exposing the cold atoms to short (0.5 microseconds) pulses of laser light. We detected these gratings by scattering a probe (light) field from them. We found that the amplitude of the gratings depended very strongly on the discrete nature of the momentum that is transferred (during the pulses) from photons in the light to the atoms. The technique we developed may allow one to measure a precise value of Plank's constant, which is a fundamental constant of nature.
My theoretical interests have concentrated on the area of "cavity quantum- electrodynamics", which is the study of systems where one or more atoms interact with a single mode of a quantized radiation field. Collaborators and I have applied the techniques of cavity quantum-electrodynamics to situations where the quantized motion of the atomic center-of-mass plays an important role. As an example, we have analyzed a system, in which a "quantum non-demolition" measurement is made of atomic momentum. More recently, we have applied cavity quantum-electrodynamic techniques to the field of "quantum computation", and have identified a simple physical system that could in principle be used to build up an arbitrary quantum computational network.
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