Atom optics and atom trapping
It is our main interest in atom optics to understand in detail how an acceleration alters the internal and center-of-mass dynamics of atoms. We have studied two cases:
- First we considered a two-level atom falling under the influence of an acceleration in a running laser wave. The behaviour of the atom turned out to be similar to that of an atom in a chirped laser wave and can be described by Landau-Zener transitions which are well known from molecular physics. (published in Phys. Rev. A 53, p. 1004 (1996)).
- We studied the question whether it is possible to compensate coherently the acceleration by applying several electromagnetic fields. We showed that for a three-level atom two counterpropagating laser beams and a hyperfine magnetic field do the job. The atom's center-of-mass performs a sequence of up and down motions that is comparable to a "trampolining", but without any reflection device (trampoline). (Phys. Rev. A 53, p. 4352 (1996)).
This periodic motion of atoms in an optical potential is related to Bloch oscillations of electrons in crystals. The method used in the previous paper suggests a new and intuitive picture for general Bloch oscillations which was developed in Europhys. Lett. 36, p. 43 (1996).