On the quantum tunneling time: Instantaneous, finite or probabilistic?

TL;DR

This paper investigates the quantum tunneling time using an exactly solvable model, revealing that tunneling dynamics are neither instantaneous nor well-defined, contributing to the ongoing debate with precise numerical results.

Contribution

The study provides an exactly solvable model for quantum tunneling under strong fields, offering new insights into the nature of tunneling time beyond existing theories.

Findings

Tunneling dynamics can significantly differ from zero or negligible traversal time.

Results do not support a single well-defined tunneling time.

Numerically exact results aim to clarify the fundamental tunneling time debate.

Abstract

Quantum particles interacting with potential barriers are ubiquitous in physics, and the question of how much time they spend inside classically forbidden regions has attracted interest for many decades. Recent developments of new experimental techniques revived the issue and ignited a debate with often contradictory results. This motivates the present study of an exactly solvable model for quantum tunneling induced by a strong field. We show that the tunneling dynamics can depart significantly from the scenario in which the barrier-traversal time is zero or very small. However, our findings do not support the idea of a well-defined tunneling time either. Our numerically exact results should help in finding a consensus about this fundamental problem.