Ultrafast coherent electron dynamics in (light-dressed) graphene
Peter Hommelhoff (FAU Erlangen and LMU Munich, Germany)
Graphene is ideally suited to expose it to strong optical fields: It absorbs only a small fraction of the light, allowing the electrons inside graphene to experience a strong optical field before damage. Based on this, we could show that we can drive electrons strongly in graphene - intraband motion and interband transitions are intricately coupled. We will show that, intriguingly, the electron dynamics is fully coherent. We could show Landau-Zener-StĂĽckelberg-Majorana physics and even use this type of interferometry to measure band structure properties. What's more, we could also already show initial applications of this ultrafast driving: We could demonstrate a logic gate with input bits encoded in the waveforms of two laser pulses. This logic gate can, in principle, lay the foundation of petahertz electronics. In the last part of the talk we will show that we can dress graphene with a circular light pulse, driving it into a Floquet topological insulator state, hence a topologically non-trivial material. With another laser pulse, we can drive electrons inside of this state and observe the optical anomalous Hall effect, where the Berry curvature takes over the role of the magnetic field.