# Time-dependent population imaging for solid high harmonic generation

## TL;DR

The paper introduces time-dependent population imaging (TDPI), a new method to visualize and analyze the ultrafast electron dynamics during high harmonic generation in solids, revealing real-time spectral and trajectory information.

## Contribution

The paper presents TDPI as an innovative, intuitive approach to directly map electron dynamics and HHG processes in solids from the TDSE solutions, including effects of CEP and two-color fields.

## Key findings

- TDPI reveals real-time photon energies of emitted harmonics.
- Short and long electron trajectories are clearly distinguished.
- TDPI effectively demonstrates HHG dynamics driven by complex laser fields.

## Abstract

We propose an intuitive method, called time-dependent population imaging (TDPI), to map the dynamical processes of high harmonic generation (HHG) in solids by solving the time-dependent Schr\"{o}dinger equation (TDSE). It is shown that the real-time dynamical characteristics of HHG in solids, such as the instantaneous photon energies of emitted harmonics, can be read directly from the energy-resolved population oscillations of electrons in the TDPIs. Meanwhile, the short and long trajectories of solid HHG are illustrated clearly from TDPI. By using the TDPI, we also investigate the effects of carrier-envelope phase (CEP) in few-cycle pulses and intuitively demonstrate the HHG dynamics driven by two-color fields. Our results show that the TDPI provides a powerful tool to study the ultrafast dynamics in strong fields for various laser-solid configurations and gain an insight into HHG processes in solids.