标题： 具有相反色散的反向旋转圆偏振激光脉冲在V型量子系统中的绝热动力学 显示英文标题

标题： Adiabatic dynamics in a V-type quantum system by oppositely chirped counterrotating circularly polarized laser pulses

摘要： 具有形状的自由电子涡旋（SEVs）最近通过原子级（1+2）共振增强多光子电离（REMPI），利用反向色散的反向旋转圆偏振（OC-CRCP）飞秒激光脉冲进行了研究。通过从微扰到非微扰的REMPI区域过渡，我们在共振V型三能级系统中识别出一种绝热激发机制，由于其与快速绝热通过（RAP）的相似性，该机制被称为V-RAP。实验上，我们观察到所测量的三维光电子动量分布（3D PMD）形状发生了显著变化，我们通过解析计算和束缚态及电离动力学的数值模拟追溯到这种机制。在V-RAP中，原子绝热地跟随OC-CRCP场，两个激发态以反相驱动，导致特定电离路径的绝热抵消，从而解释了PMD的变化。在实验中，我们将超连续谱偏振脉冲成形技术与基于速度图成像的光电子断层扫描相结合，用于生成OC-CRCP飞秒激光脉冲并重构3D PMD。重构后的PMD通过三维傅里叶分析分解为不同旋转对称性的SEVs，揭示了$c_6$对称贡献的显著增强，这是V-RAP的特征。 显示英文摘要

摘要： Shaped free electron vortices (SEVs) have recently been studied using atomic (1+2) resonance-enhanced multiphoton ionization (REMPI) by oppositely chirped counterrotating circularly polarized (OC-CRCP) femtosecond laser pulses. By transitioning from the perturbative to the non-perturbative REMPI regime, we identify an adiabatic excitation mechanism in a resonant V-type three-level system, termed V-RAP due to its similarities to rapid adiabatic passage (RAP). Experimentally, we observe a pronounced change in the shape of the measured three-dimensional photoelectron momentum distribution (3D PMD), which we trace back to this mechanism via analytical calculations and numerical simulations of the bound state and ionization dynamics. In V-RAP, the atom adiabatically follows the OC-CRCP field, with the two excited states driven in anti-phase, leading to an adiabatic cancellation of specific ionization pathways and explaining the observed changes in the PMD. In the experiment, we combine supercontinuum polarization pulse shaping to generate OC-CRCP femtosecond laser pulses with velocity map imaging-based photoelectron tomography to reconstruct the 3D PMD. The reconstructed PMDs are decomposed by 3D Fourier analysis into SEVs of different rotational symmetry, revealing a significant enhancement of the $c_6$-symmetric contribution, which is the signature of the V-RAP.