
Atom optics and atom trapping
It is our main interest in atom optics to understand in detail how an acceleration alters the internal and centerofmass dynamics of atoms. We have studied two cases:
 First we considered a twolevel 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 LandauZener 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 threelevel atom two counterpropagating laser beams and a hyperfine magnetic field do the job. The atom's centerofmass 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).

