Dynamics of Tunneling Ionization using Bohmian Mechanics

TL;DR

This paper uses Bohmian Mechanics to analyze tunneling ionization in atoms under intense infrared pulses, revealing that electrons often start from the classically forbidden region and can exit with significant kinetic energy.

Contribution

It introduces a Bohmian Mechanics framework to study electron dynamics in tunneling ionization, providing new insights into initial conditions and tunneling times.

Findings

Electrons often originate from the forbidden region rather than tunneling through the entire barrier.

Bohmian Mechanics links initial positions to asymptotic momenta.

Electrons can exit with substantial kinetic energy, supporting recent experimental results.

Abstract

Recent attoclock experiments and theoretical studies regarding the strong-field ionization of atoms by few-cycle infrared pulses revealed new features that have attracted much attention. Here we investigate tunneling ionization and the dynamics of the electron probability using Bohmian Mechanics. We consider a one-dimensional problem to illustrate the underlying mechanisms of the ionization process. It is revealed that in the major part of the below-the-barrier ionization regime, in an intense and short infrared pulse, the electron does not tunnel \through" the entire barrier, but rather already starts from the classically forbidden region. Moreover, we highlight the correspondence between the probability of locating the electron at a particular initial position and its asymptotic momentum. Bohmian Mechanics also provides a natural definition of mean tunneling time and exit position, taking account of the time dependence of the barrier. Finally, we find that the electron can exit the barrier with significant kinetic energy, thereby corroborating the results of a recent study [Camus et al., Phys. Rev. Lett. 119 (2017) 023201].