Cold atoms in quantum and non-quantum regime: atomic collisions and other experiments

Abstract

The laboratory of atomic physics in the Instituto de Física de São Carlos-USP, has initiated in 1989 its activities in the field of cold atoms. With the help of successive investments from FAPESP and others, a decent infrastructure was established and several land-marker experiments in the field have been done. Over the years, more than 100 papers were published in international journals and the S. Carlos' group has acquired an international reputation on the subject. This present proposal has the aim to give continuation to our scientific activity in this field. This proposal can be divided in three parts. In a first set of experiments, activities involving cold atom collisions will be done. The investigation of the Fine Structure-Change collisions (FSCC) as a participant channel in the process of trap loss will be investigated using an ionization-probe scheme. Here the fragments originated from P3/2--> P1/2 state change will be ionized through a highly excited state and the fraction of responsibility of FSCC to the total trap loss determined. This work shall complement our recent work (Euro Phys. J. D-99) with a higher accuracy. Trap loss involving double species trapped together will be investigated using our traditional developed techniques. Still within cold collisions, the process of photo association to produce cold long-range molecules will be performed in a heteronuclear system. The knowledge of the bound states will allow the determination of the double species scattering length. In a second set of experiments, we will give continuation to the investigation of the Bose-Einstein Condensate using Na atoms held in a cloverleaf type trap. We have been investing close to two years in this experiment that now is getting close to success. As soon as the BEC is got, studies involving the determination of thermodynamics properties as well as the observations of atomic collisions in this regime of temperature will be performed. We shall realize experimentally the transference of population from the ground state condensate to a non-ground state condensed and investigated the dynamic of this process. Preliminary theoretical investigation has shown interesting effects as a critical behavior. Finally, in a third set of experiments, we will do applications of cold atoms continuing the constructions and test of an atomic fountain as a primary standard of time and frequency. Experiments like cavity shift, collision shift and many others will be performed in the fountain. (AU)