Dominant interaction Hamiltonian approach to high harmonic generation

Carlos Zagoya, Jan-Michael Rost, and Frank Grossmann

With the recently introduced concept of dominant interaction Hamiltonians (DIH) [1], we construct the spectrum of high harmonics (HH) generated in electron-ion scattering under an intense laser field. In a semiclassical implementation, using the Herman-Kluk propagator, this is achieved by switching the interaction along classical electron trajectories between the integrable cases of the dipole coupled laser field or the ionic potential, depending on which potential is stronger.
As a side effect the intrinsically chaotic character of the dynamics is mapped onto the potential switching sequence while the trajectories become regular. As a consequence, only a few percent of the trajectories needed in full semiclassical calculations are sufficient to construct the HH spectrum.

In an analytical approach based on a superposition of a Volkov and a ground state wavefunction, we are able to determine the relative weight of the two
contributions to the total wavefunction [2].

[1] C. Zagoya, C.-M. Goletz, F. Grossmann, and Jan-Michael Rost, Phys. Rev. A 85, 041401(R) (2012)
[2] C. Zagoya, C.-M. Goletz, F. Grossmann, and Jan-Michael Rost, New Journal of Phys. 14, 093050 (2012)