Toward attosecond control of electron dynamics in two-dimensional materials

Attosecond motion of strongly driven electrons encodes information on intense laser-solid interactions, leading to material- and laser-dependent photoemission and high-harmonic generation (HHG). Here, we investigate sub-cycle control over the electron dynamics in two-dimensional (2D) materials via adjusting the relative phase of two-color pulses. Electrons in 2D solids are sensitive to the exact shape of the optical field, showing properties similar to those of isolated atoms. Accompanied by spectra modulations, the resultant harmonic yields are enhanced and the cutoff energy increases to a ratio as large as 24% when an optimized phase is applied. Different from the atomic-like HHG, however, the cutoff energy is linearly dependent on the maximum strength of the light electric field, in line with that shown in conventional bulk solids. Thus, two-dimensional materials provide a unique platform where both bulk and atomic electron dynamics can be investigated. Our work suggests a simple way to generate optimized harmonic emission with existing experimental laser technology and offers a powerful tool for analyzing attosecond quantum dynamics during laser-solid interactions.