State Key Laboratory for Mesoscopic Physics and Collaborative Innovation Center of Quantum Matter, School of Physics, Peking University, Beijing 100871, China.
Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China.
Phys Rev Lett. 2019 Aug 16;123(7):073201. doi: 10.1103/PhysRevLett.123.073201.
We demonstrate a novel attoclock, in which we add a perturbative linearly polarized light field at 400 nm to calibrate the attoclock constructed by an intense circularly polarized field at 800 nm. This approach can be directly implemented to analyze the recent hot and controversial topics involving strong-field tunneling ionization. The generally accepted picture is that tunneling ionization is instantaneous and that the tunneling probability synchronizes with the laser electric field. Alternatively, recently it was described in the Wigner picture that tunneling ionization would occur with a certain of time delay. We unify the two seemingly opposite viewpoints within one theoretical framework, i.e., the strong-field approximation (SFA). We illustrate that both the instantaneous tunneling picture and the Wigner time delay picture that are derived from the SFA can interpret the measurement well. Our results show that the finite tunneling delay will accompany nonzero exit longitudinal momenta. This is not the case for the instantaneous tunneling picture, where the most probable exit longitudinal momentum would be zero.
我们展示了一种新型的阿秒时钟，其中我们在 400nm 处添加了一个微扰线性偏振光场，以校准由 800nm 处的强圆偏振光场构建的阿秒时钟。这种方法可以直接用于分析涉及强场隧穿电离的热门和有争议的话题。人们普遍接受的观点是，隧穿电离是瞬时的，隧穿概率与激光电场同步。或者，最近在维格纳图中描述了隧穿电离将以一定的时间延迟发生。我们在一个理论框架内统一了这两个看似相反的观点，即强场近似（SFA）。我们说明，从 SFA 推导出的瞬时隧穿图像和维格纳时间延迟图像都可以很好地解释测量结果。我们的结果表明，有限的隧穿延迟将伴随着非零的出射纵向动量。对于瞬时隧穿图像，情况并非如此，在这种情况下，最可能的出射纵向动量为零。
