Orbital perspective on high-harmonic generation from solids

TL;DR

This paper explores how high-harmonic generation in solids, specifically ReS2, reveals atomic-scale electron dynamics and interference effects, advancing understanding of lightwave electronics and atomic contributions to harmonic emission.

Contribution

It provides the first atomic-scale perspective on strong-field dynamics in crystals and shows how laser parameters influence atomic contributions to high-harmonic generation.

Findings

Discovered intensity-dependent anisotropy in ReS2 harmonic emission.

Demonstrated control of atomic contributions via laser parameters.

Showed crystals with fewer atoms can be as efficient as larger ones.

Abstract

High-harmonic generation in solids allows probing and controlling electron dynamics in crystals on few femtosecond timescales, paving the way to lightwave electronics. In the spatial domain, recent advances in the real-space interpretation of high-harmonic emission in solids allows imaging the field-free, static, potential of the valence electrons with picometer resolution. The combination of such extreme spatial and temporal resolutions to measure and control strong-field dynamics in solids at the atomic scale is poised to unlock a new frontier of lightwave electronics. Here, we report a strong intensity-dependent anisotropy in the high-harmonic generation from ReS$_2$ that we attribute to angle-dependent interference of currents from the different atoms in the unit cell. Furthermore, we demonstrate how the laser parameters control the relative contribution of these atoms to the high-harmonic emission. Our findings provide an unprecedented atomic perspective on strong-field dynamics in crystals and suggest that crystals with a large number of atoms in the unit cell are not necessarily more efficient harmonic emitters than those with fewer atoms.