Hidden avoided crossings and interference in intrashell transitions driven by harmonic fields

I. PILSKOG; D. FREGENAL; M. FØRRE; E. HORSDAL

Kalamazoo

Conferencia; XXVI International Conference on Photonic, Electronic and Atomic Collisions; 2009

We have investigated intrashell transitions in lithium n = 25 Rydberg atoms. The Rydberg atoms are exposed to two electric fields, one switching field and one harmonic oscillating field, and one homogeneous magnetic field. The system is initially prepared in the uppermost Stark state in the manifold, which is nondegenerate. We measure the adiabatic probability as a function of the switching field’s final angle, with respect to a given axis.For angles larger than 18 degrees and smaller than −18 degrees an oscillatory behavior is observed in the transition probability for the lithium Rydberg atoms, that are not present in the hydrogenic counterpart. This has earlier been reported as an interference effect due to two hidden avoided crossings caused by the lithium core. In the present work, we observe an increased oscillatory behavior due to the harmonic field. As the strength of the harmonic field is increased,so are the amplitudes of the oscillations. Further it is observed that when the strength of the magnetic field is varied, the interval of angles that is affected by these oscillations also varies.We have developed a theoretical model that quantitatively agrees with the experiments, andall the main features are present. Furthermore these simulations show that the system is basically a two level system with significant transition only between the two Stark states. Motivated by this we have developed an approximate two level model for the system, which reproduces the experimental features.