The imaginary part of the high-harmonic cutoff
The imaginary part of the high-harmonic cutoff
复制标题
高次谐波截止的虚部
DOI：
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
M. Lewenstein
中科院分区：
文献类型：
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作者：
E. Pisanty;M. Ciappina;M. Lewenstein
高次谐波的产生--由强激光场驱动的原子电子的电离和随后的复合而产生的高频辐射--被广泛地理解为使用从鞍点近似导出的准经典轨迹形式论，其中每个鞍点对应于一个复值轨迹，其复合有助于谐波发射。然而，将这些鞍点归类为单独的量子轨道仍然是形式主义的一个高摩擦部分。在这里，我们提出了一种方案来分类这些轨迹，基于对对应于谐波截止的(复杂)时间的自然识别。这种识别还为截止能量提供了一个自然的复数值，其虚部控制着在截止时相遇的量子轨道之间的量子路径干扰的强度。我们的构造给出了一种有效的方法，可以通过求解一个单鞍点方程来估计一大类驱动波形的截止位置和亮度。它还允许我们探索由非平凡波形诱导的量子轨道形成的黎曼曲面的复杂拓扑。
High-harmonic generation—the emission of high-frequency radiation by the ionization and subsequent recombination of an atomic electron driven by a strong laser field—is widely understood using a quasiclassical trajectory formalism, derived from a saddle-point approximation, where each saddle corresponds to a complex-valued trajectory whose recombination contributes to the harmonic emission. However, the classification of these saddle points into individual quantum orbits remains a high-friction part of the formalism. Here we present a scheme to classify these trajectories, based on a natural identification of the (complex) time that corresponds to the harmonic cutoff. This identification also provides a natural complex value for the cutoff energy, whose imaginary part controls the strength of quantum-path interference between the quantum orbits that meet at the cutoff. Our construction gives an efficient method to evaluate the location and brightness of the cutoff for a wide class of driver waveforms by solving a single saddle-point equation. It also allows us to explore the intricate topologies of the Riemann surfaces formed by the quantum orbits induced by nontrivial waveforms.
影响因子：
8.6
作者：
Chipperfield, L. E.;Robinson, J. S.;Marangos, J. P.
通讯作者：
Marangos, J. P.
影响因子：
8.6
作者：
T. Keil;S. Popruzhenko;Dieter Bauer
通讯作者：
T. Keil;S. Popruzhenko;Dieter Bauer