Interferometry has been at the heart of wave optics since its early stages, resolving the coherence of the light field and enabling the complete reconstruction of the optical information it encodes. Transferring this concept to the attosecond time domain shed new light on fundamental ultrafast electron phenomena. Here we introduce attosecond-gated interferometry and probe one of the most fundamental quantum mechanical phenomena, field-induced tunnelling. Our experiment probes the evolution of an electronic wavefunction under the tunnelling barrier and records the phase acquired by an electron as it propagates in a classically forbidden region. We identify the quantum nature of the electronic wavepacket and capture its evolution within the optical cycle. Attosecond-gated interferometry has the potential to reveal the underlying quantum dynamics of strong-field-driven atomic, molecular and solid-state systems.

干涉测量从早期阶段就一直是波动光学的核心，它解决了光场的相干性，并能够完全重建它编码的光学信息。将这一概念转移到阿秒时域为基本的超快电子现象提供了新的思路。在这里，我们介绍了阿秒门控干涉测量并探索了最基本的量子力学现象之一，即场致隧道效应。我们的实验探索了隧道势垒下电子波函数的演变，并记录了电子在经典禁区传播时所获得的相位。我们确定了电子波包的量子性质，并捕获了它在光周期内的演变。