Electron tunneling times

TL;DR

This paper reviews the concept of tunneling times in quantum mechanics, discussing various definitions and experimental methods involving ultrafast laser techniques and solid-state measurements.

Contribution

It provides a comprehensive overview of the evolution of tunneling time concepts and compares experimental approaches in atomic and solid-state systems.

Findings

Different definitions of tunneling time are analyzed.

Experiments using femtosecond lasers measure tunneling via field rotation.

Solid-state measurements infer tunneling time from current-voltage characteristics.

Abstract

Tunneling is one of the most bizarre phenomena in quantum mechanics. An attempt to understand it led to the next natural question of how long does a particle need to tunnel a barrier. The latter gave rise to several definitions such as the phase, dwell, Larmor and traversal times among others. A short review of the evolution of these time concepts, followed by an account of experiments involving field-induced tunnel ionization and electron tunneling in a solid state junction is presented here. Whereas the former experiments use sophisticated techniques involving femtosecond laser pulses and determine the tunneling time by mapping the angle of rotation of the field vector to time, like the hands of a watch, the latter provides a simpler method through the measurement of current-voltage characteristics of the junction.