Photoelectron tomography of electron vortices from tailored CEP-stable few-cycle and multicolour optical fields

利用载波包络相位(CEP)稳定的偏振定制飞秒激光场来操纵相干光诱导电子动力学是QUTIF第二个资助期的核心科学目标。在QUTIF的第一个资助期，我们实现了一个超连续偏振脉冲整形器，用于产生定制的CEP稳定的几周脉冲和可变频率比的双色场[OPT.快讯25(2017年)12518]。利用反向旋转的圆极化脉冲序列与光电子层析成像相结合，首次实验证明了原子的多光子电离产生的自由电子涡旋。莱特牧师。在QUTIF的第二个资助期，我们计划通过探索先进的物理激励相干控制场景来扩展我们的初步研究，利用为偏振定制的CEP稳定的少周期和多颜色飞秒激光场来实现模型系统的多光子电离。特别强调的是实施控制方案，利用基于脉冲整形器的可变频率比双色场来操纵来自相位稳定的超连续辐射的M光子与N光子干扰。我们最初的研究重点将是自由电子涡旋的高级相干控制。例如，我们将通过相反宇称的离子态的干涉来演示具有奇数臂的CEP敏感的双色自由电子涡旋，包括单臂涡旋，映射Rydberg型束缚态动力学，并在连续谱中通过光谱干涉测量频率混合路径的电离时间。首先，我们将在微扰区的准单电子和多电子系统上验证这些方案，并在非微扰区和隧道电离区继续探索这些方案。利用光电子层析成像测量的三维光电子动量分布，提取有关受控量子动力学的详细信息。我们将通过两项技术改进我们的实验装置：(1)在我们的光电子能谱仪中安装原子束/分子束，以抵消Gouy相对空间CEP平均的影响；(2)设计和实现一种“双整形器”，即一种用于CEP稳定超连续谱的新型极化整形器。结合“双整形器”提供对电场形状的精确控制和光电子断层扫描的高度微分检测，将使我们能够展示对原子和分子中相干电子动力学的前所未有的操纵。

Manipulating coherent light-induced electron dynamics with Carrier Envelope Phase (CEP) stable polarization-tailored femtosecond laser fields is a scientific objective at the heart of the second funding period of QUTIF.In the first funding period of QUTIF, we have implemented a supercontinuum polarization pulse shaper for the generation of tailored CEP-stable few-cycle pulses and bichromatic fields with variable frequency ratios [Opt. Express 25 (2017) 12518]. Using counterrotating circularly polarized pulse sequences in combination with photoelectron tomography, we presented the first experimental demonstration of free electron vortices from multiphoton ionization of atoms [Phys. Rev. Lett. 118 (2017) 053003] which have attracted much attention, both theoretically and experimentally.In the second funding period of QUTIF, we plan to extend our preliminary research by exploring advanced physically motivated coherent control scenarios for multiphoton ionization of model systems using polarization-tailored CEP-stable few-cycle and multicolour femtosecond laser fields. Special emphasis lies on the implementation of control scenarios to manipulate M- vs. N-photon interferences using pulse shaper-based variable frequency-ratio bichromatic fields from phase-stable supercontinuum radiation. The initial focus of our investigations will be on advanced coherent control of free electron vortices. For example, we will demonstrate CEP-sensitive bichromatic free electron vortices with an odd number of arms, including a single-armed vortex, by interference of ionic states with opposite parity, map Rydberg-type bound state dynamics and measure the ionization time of frequency mixing pathways by spectral interference in the continuum. Initially, we will validate these scenarios on quasi-one- and multi-electron systems in the perturbative regime and continue to explore these schemes in the non-perturbative and tunnel ionization regime. Three-dimensional photoelectron momentum distributions, measured by photoelectron tomography, are utilized to extract detailed information on the controlled quantum dynamics. We will refine our experimental set-up by two technical improvements: (1) the installation of an atomic / molecular beam in our photoelectron spectrometer to counteract spatial CEP-averaging by the Gouy phase and (2) the design and implementation of a ‘TWIN-shaper’, i.e. a novel polarization shaper for CEP-stable supercontinua. Combining the ‘TWIN-shaper’ to provide precise control on shape the electric field with highly differential detection by photoelectron tomography will allow us to demonstrate unprecedented manipulation of coherent electron dynamics in atoms and molecules.