A unified theory of tunneling times promoted by Ramsey clocks

TL;DR

This paper introduces a unified operational framework using Ramsey clocks to measure tunneling times in quantum systems, resolving ambiguities and refuting superluminal tunneling claims.

Contribution

It develops a comprehensive approach that unifies various tunneling time definitions and links them to atomic clock standards, avoiding classical trajectory assumptions.

Findings

No superluminal tunneling observed

Unified framework for tunneling delay definitions

Operational method using Ramsey sequences

Abstract

What time does a clock tell after quantum tunneling? Predictions and indirect measurements range from superluminal or instantaneous tunneling to finite durations, depending on the specific experiment and the precise definition of the elapsed time. Proposals and implementations utilize the atomic motion to define this delay, even though the inherent quantum nature of atoms implies a delocalization and is in sharp contrast to classical trajectories. Here, we rely on an operational approach: we prepare atoms in a coherent superposition of internal states and study the time read off via a Ramsey sequence after the tunneling process without the notion of classical trajectories or velocities. Our operational framework (a) unifies definitions of tunneling delay within one approach; (b) connects the time to a frequency standard given by a conventional atomic clock which can be boosted by differential light shifts; and (c) highlights that there exists no superluminal or instantaneous tunneling.