Stark effect of Kramers-Henneberger atoms

Dynamics of Kramers-Henneberger atoms in focused laser beams of circular polarization

In intense laser fields, electrons of atoms will follow the laser field and undergo quiver motion just like free electrons but still weakly bound to the atomic core, thus forming a set of specific dressed states named Kramers-Henneberger (KH) states, which comprise the KH atoms. In a focused laser beam, in addition to Ponderomotive (PM) force, KH atoms will experience KH force, which is unique to KH atoms. We examine both PM and KH forces as well as corresponding velocity gain of hydrogen and helium atoms in a focused laser field with circular polarization. We work out laser parameters which can be used in experimental confirmation of circularly polarized KH atoms.

Symmetry breaking of Kramers-Henneberger atoms by ponderomotive force

It was believed that Kramers-Henneberger (KH) atoms in a linearly polarized superintense laser field exhibit the structure of "dichotomy." At large quiver amplitude, the two lowest-lying eigenstates are degenerated and both have a dichotomous symmetric structure. However, this is not a common structure for KH atoms because KH atoms practically can only exist in the focused laser field. However, in a focused laser, KH state electrons usually experience the ponderomotive force, which will lift the degeneracy and break the symmetry.

A balancing act of two electrons on a symmetric double-well barrier in a high frequency oscillating field

The dynamics of two electrons in a three-dimensional symmetric double-well quantum system is controlled using a high frequency oscillating electric field, achieving pairing of electrons and barrier-top localization. The field parameters of oscillating electric field intensity and frequency which are required to induce such an effect of barrier-top stabilization are easily estimated using time-independent Kramers-Henneberger electronic structure Full Configuration Interaction (FCI) calculations in an oscillating frame of reference with a Gaussian basis set. In the presence of the laser, the energy of the two-electron system in the symmetric double-well is found to be minimized when the barrier-top dynamic stabilization happens. Furthermore, the barrier-stabilized state finds importance in achieving a temporal control over electronic ionization. From approximate time-dependent calculations in the laboratory frame, the signatures of the barrier stabilized state are realized and it is observed that the paired-up state remains stable as long as the continuous wave region of the laser pulse is on. Ionization happens as soon as the laser pulse is switched off, because of the increased electronic repulsion in the paired up barrier-top state, thus giving a temporal control over laser-induced ionization.