Chaotic Rydberg atoms with broken time-reversal symmetry

The dynamics of Rydbeg states of atomic hydrogen perturbed simultaneously b y a static electric field and a resonant microwave held of elliptical polar ization is analyzed in the quantum perturbative limit of small amplitudes. For some configurations, the secular motion (i.e., evolution in time of the elliptical electronic trajectory) may be classically predominantly chaotic . By changing the orientation of the static field with respect to the polar ization of the microwave field, one can modify the global symmetries of the system and break any generalized time-reversal invariance. This has a dram atic effect on the statistical properties of the energy levels.