Quantum interference in strong-field ionization by a linearly polarized laser pulse, and its relevance to tunnel exit time and momentum

TL;DR

This paper explores quantum interference effects in strong-field ionization caused by linearly polarized laser pulses, revealing blurred tunneling characteristics and proposing improved classical models based on quantum momentum for better understanding electron escape dynamics.

Contribution

It introduces a quantum interference perspective in strong-field ionization and develops a method to reconstruct initial conditions from electron momentum data.

Findings

Quantum interference significantly affects tunneling in strong fields.

Tunneling is less spatially and temporally distinct than classical models suggest.

A new classical approximation based on quantum momentum improves modeling accuracy.

Abstract

We investigate the liberation of an atomic electron by a linearly polarized single-cycle near-infrared laser pulse having a peak intensity that ensures tunneling. Based on phase space analysis and energy distribution in the instantaneous potential, we reveal the importance of quantum interference between tunneling and over-the-barrier pathways of escape. Tunneling is blurred both in space and time, and the contribution of tunneling at the mean energy is almost negligible. We suggest and justify improved initial conditions for a classical particle approximation of strong-field ionization, based on the quantum momentum function, and we show how to reconstruct them from the detected momentum of an escaped electron.