标题： 阿秒四波混频光谱中的非微扰效应 显示英文标题

标题： Non-perturbative Effects in Attosecond Four-Wave Mixing Spectra

摘要： 我们研究了氩气对四波混频脉冲序列的非线性光学响应，该脉冲序列由一个极紫外脉冲、一个重叠的共线红外脉冲和一个非共线延迟红外脉冲组成。从共线光束吸收一个极紫外光子和一个红外光子依次激发$3s^{-1}4p$明态和{$3s^{-1}3d/5s$}暗态。随后从非共线光束吸收一个红外光子导致产生角度偏移的极紫外发射，其随延迟时间的变化编码了自电离态之间的耦合、暗态寿命以及非微扰效应的信息。我们的测量结果和\emph{从头开始}对角度四波混频信号的模拟均显示出延迟依赖性的双峰结构，并且彼此高度一致。我们将信号中心的最小值归因于由红外脉冲驱动的暗态与$3s^{-1}4p$共振之间的快速拉比循环，这导致最终跃迁振幅中的破坏性干涉。 显示英文摘要

摘要： We study the nonlinear optical response of argon to a four-wave-mixing pulse sequence consisting of an extreme ultraviolet pulse, an overlapping collinear IR and an non-collinear delayed IR pulses. Absorption of an extreme ultraviolet and an IR photon from the collinear beams excites, sequentially, the $3s^{-1}4p$ bright state and the {$3s^{-1}3d/5s$} dark states. The subsequent absorption of an IR photon from the non-collinear beam results in an angled extreme ultraviolet emission whose variation with delay encodes coupling between autoionizing-states, dark-state lifetimes, and non-perturbative effects. Both our measurements and \emph{ab initio} simulations of the angled four-wave-mixing signal show a double-peak structure in delay dependence, in excellent agreement with each other. We attribute the minimum at the center of the signal to the rapid Rabi cycling, driven by the IR pulse, between dark states and the $3s^{-1}4p$ resonance, which results in the destructive interference in the final transition amplitude.