Linear Stark effect for a sulfur atom in strong high-frequency laser fields

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.

Stark effect of Kramers-Henneberger atoms

The Electric Stark effect of a Kramers-Henneberger (KH) state of hydrogen atoms in both linearly and circularly polarized laser fields is studied. For the ground KH state of H atoms with a small quiver amplitude, the quadratic Stark effect is observed. For a large quiver amplitude, the Stark effect is quadratic only in a weak electric field and quickly changes to linear as the electric field increases. The atomic structure of the KH state is very sensitive to the electric field and can be easily polarized. The huge polarizability and induced dipole moment are comparable to those of Rydberg atoms.