Modification of atomic energy levels by two rotating rf fields

V. N. Streltsov

T. Ya. Karagodova

In the intense radiation fields with power density from 104W/cm2 to 109W/cm2 the essential modification of electronic states of atoms occurs displaying, in particular, in modifications of resonant fluorescence (rf) spectra. We use 'Fermi golden rule' for calculations of relative intensities and frequencies for rf multiplet for real multilevel initially unexcited atoms in two monochromatic laser fields of arbitrary intensity resonant to adjacent transitions of (Xi) or (Lambda) types and magnetic field, giving the level splittings of different values from Zeeman to Paschen-Back effect. The dependence of quasienergies on parameters obtained with the help of a sorting program permits us to define the values of parameters for which the states of the system are mixed and so to receive the correct probability amplitudes for instantaneous or adiabatic regimes of switching the perturbation. The analysis of the quasienergies and form of rf spectra permits us to get relations between the form of the spectra and modifications of electronic structure of the atom due to radiation fields and external magnetic field.

Robert Karplus, Abraham Klein, Julian Schwinger

Shuai Yang, Jun Xu, Shi‐Yao Zhu +1 more

Quantum interference in spontaneous emission from a four-level atom is investigated with the counter-rotating terms and the energy shifts included. The atom has two upper levels which are coupled to a common lower level by the same vacuum modes and are driven by a coherent field to an auxiliary level. The effect of the counter-rotating terms in the coupling through the vacuum modes is taken into account by a unitary transformation method. We show how the quantum interference due to the energy shifts affects the spontaneous emission.

T. S. Subbaraya, Kalkunte S. Seshadri, N. A. Narayana Rao

Noriaki Tsukada, T. Yabuzaki, Toru Ogawa

The evolution of magnetization of optically pumped atoms in the presence of two rotating rf fields with different frequencies is investigated by using the phenomenological Bloch equation. It is shown that the new type resonances, which are due to the effect of the transverse pumping, together with the ordinary magnetic resonance and the multiple quantum transitions are realized under these conditions. It is also shown that the Hanle curve is broadened by a rotating rf field in the same manner as by an oscillating rf field, and is shifted towards high field region as the intensity of the rotating rf field is increased. The results obtained are, in general, applicable to the case of an elliptically rotating rf field, which is superposition of two rotating rf fields.