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arXiv 1707.05445physics.atom-ph
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氢原子中的阿秒角拖尾和隧穿时间

Attosecond angular streaking and tunnelling time in atomic hydrogen

U. Satya Sainadh, Han Xu, Xiaoshan Wang, Atia-Tul-Noor, William C. Wallace, Nicolas Douguet, Alexander W. Bray, Igor Ivanov, Klaus Bartschat, Anatoli Kheifets, … 展开作者

U. Satya Sainadh, Han Xu, Xiaoshan Wang, Atia-Tul-Noor, William C. Wallace, Nicolas Douguet, Alexander W. Bray, Igor Ivanov, Klaus Bartschat, Anatoli Kheifets, R. T. Sang, I. V. Litvinyuk

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摘要：

隧道效应是量子力学的重要特征之一，它引发了一场关于“隧道效应时间”的价值、意义和解释的争论。直到最近，这场辩论还纯粹是理论性的，人们认为这一过程对所有实际目的来说都是即时的。这种情况随着超快激光的发展而改变，特别是用于探测电子阿秒动力学的“阿钟”技术。虽然最初的原子钟测量暗示了瞬时隧穿，但后来的实验与这些发现相矛盾，声称测量到了有限的隧穿时间。在每种情况下，这些测量都是用多电子原子进行的。原子氢（H），最简单的原子系统与一个单一的电子，可以“精确地”（仅受数值限制）建模使用3D-TDSE的数值解与测量的实验参数，并作为一个方便的基准准确的实验测量和计算。在这里，我们报告的第一attocock实验进行H和发现，我们的实验确定的偏移角是在很好的协议与准确的3D-TDSE模拟使用我们的实验脉冲参数。同样的模拟与短程汤川势的结果在零偏移角的所有强度。我们的结论是，在attocock实验中测得的偏移角起源于电子散射的长程库仑势没有隧道时间延迟的贡献。这一结论得到了经验观察的支持，即电子偏移角严格遵循库仑势作用下经典卢瑟福散射电子偏转角的简单公式。因此，我们确认，在H，隧穿是瞬时的（上限为1.8）在我们的实验和数值的不确定性。

英文摘要：

Tunnelling, one of the key features of quantum mechanics, ignited an ongoing debate about the value, meaning and interpretation of 'tunnelling time'. Until recently the debate was purely theoretical, with the process considered to be instantaneous for all practical purposes. This changed with the development of ultrafast lasers and in particular, the 'attoclock' technique that is used to probe the attosecond dynamics of electrons. Although the initial attoclock measurements hinted at instantaneous tunnelling, later experiments contradicted those findings, claiming to have measured finite tunnelling times. In each case these measurements were performed with multi-electron atoms. Atomic hydrogen (H), the simplest atomic system with a single electron, can be 'exactly' (subject only to numerical limitations) modelled using numerical solutions of the 3D-TDSE with measured experimental parameters and acts as a convenient benchmark for both accurate experimental measurements and calculations. Here we report the first attoclock experiment performed on H and find that our experimentally determined offset angles are in excellent agreement with accurate 3D-TDSE simulations performed using our experimental pulse parameters. The same simulations with a short-range Yukawa potential result in zero offset angles for all intensities. We conclude that the offset angle measured in the attoclock experiments originates entirely from electron scattering by the long-range Coulomb potential with no contribution from tunnelling time delay. That conclusion is supported by empirical observation that the electron offset angles follow closely the simple formula for the deflection angle of electrons undergoing classical Rutherford scattering by the Coulomb potential. Thus we confirm that, in H, tunnelling is instantaneous (with an upperbound of 1.8 as) within our experimental and numerical uncertainty.

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