We present an ab initio investigation of the time-frequency characteristics of high-order harmonic generation (HHG) calculated by solving accurately and efficiently the time-dependent Schrödinger equation by means of the time-dependent generalized pseudospectral method. We extend a new synchrosqueezing transform (SST) to obtain the time-frequency spectra of the HHG and the dynamical phase associated with the dipole-emission time profile. The SST time-frequency analysis allows us to explore in depth the dynamics and contributions of the quantum trajectories in HHG. Particularly it uncovers the subtle details of the spectral and temporal fine structures of the HHG and provides novel insights regarding the dynamical origin of the HHG in below-threshold harmonic regimes.

中文翻译：

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探索由多周期近红外激光脉冲驱动的原子的高次谐波生成中的光谱和时间分辨动力学

我们提出了从头开始研究高阶谐波产生（HHG）的时频特性的方法，该方法是通过依赖于时间的广义伪谱方法准确有效地求解与时间有关的Schrödinger方程而得出的。我们扩展了一个新的同步压缩变换（SST），以获得HHG的时频频谱以及与偶极子发射时间曲线相关的动态相位。SST时频分析使我们能够深入探索HHG中量子轨迹的动力学和贡献。特别是，它揭示了HHG的光谱和时间精细结构的细微细节，并提供了有关在阈值以下谐波范围内HHG动力学起源的新颖见解。