Light-field driven electron dynamics in graphene

Graphene is a unique material for lightfield-controlled electron dynamics inside of a (semi-) metal. Its Dirac cone dispersion relation represents a two-level system to study intricately coupled intraband motion and interband (Landau-Zener) transitions driven by the optical field of phase-controlled few-cycle laser pulses [1, 2, 3, 4]. Based on the coupled nature of the intraband and interband processes, we observe repeated coherent Landau-Zener transitions between valence and conduction band separated by around half an optical period of $\sim$1.3 fs, fully supported by numerical simulations. Because of the extremely fast dynamics, fully coherent Landau-Zener-Stückelberg (LZS) interferometry manifests itself in ultrafast current injection, with a record-fast turn-on timescale of 1 fs for a current in a metal. Moreover, we could show complex electron trajectory control by tailoring the polarization state of the driving laser pulses. This way, we can manipulate LZS interference [3].\\ $[1]$ T. Higuchi, C. Heide et al., Nature 550, 224–228 (2017)\\ $[2]$ C. Heide, T. Boolakee et al., NJP 21, 045003 (2019)\\ $[3]$ C. Heide, T. Higuchi et al., PRL 121, 207401 (2018)\\ $[4]$ C. Heide, M. Hauck et al., Nat. Photonics (2020) https://doi.org/10.1038 /s41566-019-0580-6