Contact principal :	Chris Westbrook
Autres contacts :	Alain Aspect
	Laurent Sanchez-Palencia

Description des activités de recherche :

One broad general theme of our work is the exploration of analogies between optics with light (or photons) and optics with atoms. Along with many other groups in the world, we have been involved in the development of mirrors, lenses, beam splitters, diffraction gratings and interferometers for atoms. The advent of Bose-Einstein condensation in 1995 has revolutionized the field because it has provided us with the analog of the laser, i.e. a coherent source.

From 1991 to 2001, an important avenue of our research was the development and study of atom mirrors. We focussed mainly on mirrors using evanescent waves. Using these devices we were able to produce not only mirrors but also reflection diffraction gratings. An important result of our work included a precise measurement of the van der Waals force between a neutral atom and the glass surface of the mirror. We also discovered to our surprise, that the quality of these mirrors was very sensitive to the quality of the glass surface as well as to sources of stray light.

After the 1^st demonstration of Bose-Einstein condensation (BEC) in the lab in JILA, we turned our attention to this fascinating form of matter. We produced our first condensate in 1998, using a novel type of electromagnet with iron cores. Since then we have constructed several other BEC experiments. The scientific work on BEC has centered around the several themes:

• BEC in highly elongated geometries nearly 1 dimensional geometries. In this situation, even below the BEC transition temperature, the condensate is not really a condensate, but rather a "quasi-condensate" which exhibits a phase coherence length shorter than the length of the sample.
• The study of atom lasers. Atom lasers are in essence "beams of BEC". Typically one produces a BEC and then uses various schemes to "outcouple" the atoms as a beam. We have been studying the atom-optical characteristics of such beams and their potential applications to atom interferometry.
• BEC in atom chips. Atom chips promise to provide a compact and relatively inexpensive means of producing BEC’s. As such, applications of cold atoms to atom interferometry may become much more portable and feasible. Chips also permit the production of 1 dimensional gases and camplement the studies described in 1).
• BEC of metastable helium. The unique feature of metastable helium is that the atoms can be detected on an atom by atom basis and with excellent time resolution (1 ns) using micro-channel plates. This feature permits many novel experiments in which correlations between atoms are present.
• Theoretical activities. Our theoretical work is devoted to the investigation of quantum gases in meanfield or strongly correlated regimes. Our aim is threefold: (i) propose and analyze atomic physics experiments aiming at studying fundamental quantum questions, (ii) analyze the possibilities of atomic physics to realize exotic quantum systems, (iii)develop analytic and numerical methods for quantum atom optics.

Pour en savoir plus : voir en ligne Optique atomique @ LCFIO