Underbarrier interference

TL;DR

This paper investigates how tangent momentum and barrier inhomogeneity affect quantum tunneling, revealing that non-zero tangent momentum can significantly enhance tunneling probability by disrupting wave interference.

Contribution

It introduces the concept of underbarrier interference disruption by tangent momentum and barrier inhomogeneity, showing a new mechanism for increased tunneling.

Findings

Finite tangent momentum destroys interference, increasing tunneling flux.

Barrier inhomogeneity leads to wave caustics, affecting tunneling behavior.

Significant tunneling occurs even at energies well below the barrier.

Abstract

Quantum tunneling through a two-dimensional static barrier becomes unusual when a momentum of an electron has a tangent component with respect to a border of the prebarrier region. If the barrier is not homogeneous in the direction perpendicular to tunneling a fraction of the electron state is waves propagating away from the barrier. When the tangent momentum is zero a mutual interference of the waves results in an exponentially small outgoing flux. The finite tangent momentum destroys the interference due to formation of caustics by the waves. As a result, a significant fraction of the prebarrier density is carried away from the barrier providing a not exponentially small penetration even through an almost classical barrier. The total electron energy is well below the barrier.