Dynamically Assisted Tunneling in the Floquet Picture

TL;DR

This paper investigates how an oscillating electric field can enhance quantum tunneling through different potential barriers, revealing resonance effects and limitations of the time-averaged approximation, with implications for solid state physics and nuclear fusion.

Contribution

It introduces a Floquet-based numerical approach to analyze dynamically assisted tunneling and identifies resonance signatures at specific energies, advancing understanding of tunneling enhancement mechanisms.

Findings

Resonance signatures occur when incident energy equals driving frequency.

Breakdown of the time-averaged potential approximation at resonance.

Applicable to models like rectangular and Coulomb potentials.

Abstract

We study how tunneling through a potential barrier $V(x)$ can be enhanced by an additional harmonically oscillating electric field ${\mathfrak E}(t)={\mathfrak E}_0\cos(\omega t)$. To this end, we transform into the Kramers-Henneberger frame and calculate the coupled Floquet channels numerically. We find distinct signatures of resonances when the incident energy $E$ equals the driving frequency $\omega=E$ which clearly shows the breakdown of the time-averaged potential approximation. As a simple model for experimental applications (e.g., in solid state physics), we study the rectangular potential, which can also be benchmarked with respect to analytical results. Finally, we consider the truncated Coulomb potential relevant for nuclear fusion.