The role of tunneling in the ionization of atoms by ultrashort and intense laser pulses

Abstract

Using the improved soft-core potential of Majorosi et al, it is shown that classically allowed transport competes with quantum tunneling during the ionization of atoms by ultrashort and intense laser pulses. This is done by comparing exact probability densities with the ones obtained from purely classical propagation using the Truncated Wigner Approximation. Not only is classical transport capable of moving trajectories away from the core, but it can also furnish ionization probabilities of the same order as the quantum ones for intensities currently employed in experiments. Our results have implications ranging from a conceptual correction to the three-step model of higherharmonics generation to the ongoing debate about tunneling time measurements in attoclocks.