Cold Atoms, Cold Molecules, and Spectroscopy

Suny At Stony Brook, Stony Brook NY

Investigators

Abstract

The work to be performed under this grant consists of two components. One component will involve theoretical modeling of ensembles of cold atoms in a Bose-Einstein condensate, in which all atoms are in the lowest quantum level, at temperatures less than a microdegree absolute. Many recent experiments, including some at Stony Brook, have been performed on such atomic ensembles when placed in a periodic potential. These experiments can mimic, in a controllable way, the periodic potential in a crystalline solid, such as a semiconductor or superconductor. One question to be addressed is whether the atoms remain in the lowest quantum state when the periodic potential is applied, perhaps suddenly, or whether excitations are induced. The theoretical work will help to interpret recent experimental observations on this point. The other component pertains to work in several laboratories world-wide directed to the production of ultra-cold diatomic molecules, also at nanoKelvin temperatures. In recent years, we have been analyzing spectroscopic data on diatomic molecules to be able to tell experimentalists what laser wavelengths to use to induce two cold atoms to bind together into a cold molecule. The next stage of the work is to analyze effects of nuclear spin structure (analogous to effects that are used in nuclear magnetic resonance imaging), which become predominant in certain regimes. With regard to the broader impact of this work, it can be said that the attainment of extremely low temperatures of atoms and now of diatomic molecules allows one to overcome averaging effects at normal temperatures, when a vast number of quantum levels are occupied. By selecting particles in the lowest quantum state, it is possible to obtain much more precise information on their interactions and on their behavior. It has been possible to better understand effects that occur in complicated naturally occurring systems by being able to vary the conditions imposed on the cold atoms. For example, a periodic laser light field can mimic the periodic potential in a crystalline lattice, but over a range of lattice amplitude and wavelength. This has already produced new insights into phenomena such as high temperature (above 50 Kelvin) superconductivity and also into the complicated interactions within atomic nuclei. Superconductors are now used in many reseach applications. Their use in electrical power transmission in areas of high electrical current density could improve the efficiency of the U. S. power grid.