标题： 飞秒激光场中氦原子的实时演化：阿秒分辨的双色光电子发射研究 显示英文标题

标题： Real-time evolution of a laser-dressed Helium atom: Attosecond-resolved two-color photoionization study

摘要： 使用极端紫外线阿托秒脉冲序列，我们在中等强度（~10^12 W/cm^2）飞秒激光脉冲存在的情况下，研究了氦原子的光致电离动力学。通过精确测量离子产率和光电子角分布，实时追踪了激光修饰原子的电子结构。利用Floquet形式主义解释了光激发路径之间的量子干涉。当激光脉冲强度在飞秒时间尺度上变化时，我们观察到由不同原子共振介导的电离通道之间的转变。对于每个通道，提取了干涉路径的量子相位并与模拟结果进行了比较。我们的结果阐明了强场中的光致电离机制，并为光吸收/电离控制方案打开了大门。 显示英文摘要

摘要： Using extreme-ultraviolet attosecond-pulse-trains, we investigate the photoionization dynamics of a Helium atom in the presence of moderately-strong (~10^12 W/cm^2) femtosecond laser pulses. The electronic structure of a laser-dressed atom is traced in real-time through precision measurements of ion-yields and photo-electron angular distributions. Quantum interferences between photo-excitation paths are interpreted using the Floquet formalism. As the laser pulse intensity ramps on femtosecond timescales, we observe transitions between ionization channels mediated by different atomic resonances. The quantum phase of interfering paths is extracted for each channel and compared with simulations. Our results elucidate photoionization mechanisms in strong-fields and open the doors for photo-absorption/ionization control schemes.