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SYFC: Symposium Designing Quantum Materials with Light: From Floquet to Cavity Engineering

SYFC 1: Designing Quantum Materials With Light: from Floquet to Cavity Engineering

SYFC 1.5: Hauptvortrag

Montag, 9. März 2026, 11:45–12:15, HSZ/AUDI

Lightwave-driven electrons in a Floquet topological insulator — Daniel Lesko^{1, 2}, Tobias Weitz^{1, 2}, Weizhe Li¹, Selina Nöcker^{1, 2}, Celina Hüttner¹, Tamara Pröbster¹, Simon Wittigschlager¹, Christian Heide^{1, 3}, Ofer Neufeld⁴, and •Peter Hommelhoff^{1, 2} — ¹Department Physik, Friedrich-Alexander-Universität, Erlangen — ²Fakultät für Physik, Ludwig-Maxilians-Universität, München — ³University of Central Florida, Orlando, Fl, USA — ⁴Technion, Haifa, Israel

Topological insulators enable novel quantum and electronic phenomena but are limited by material constraints. Floquet topological insulators (FTIs), created by time-periodic driving, promise tunable topological properties and petahertz operation. We demonstrate optical control of photocurrents in light-dressed graphene, where circularly polarized pulses induce an FTI state and phase-locked second-harmonic pulses drive electron dynamics. This enables measurement of all-optical anomalous Hall and valley-polarized photocurrents, revealing sub-cycle phase sensitivity and dynamical symmetry selection rules. Supported by ab-initio and analytical theory, our results establish a bridge between Floquet and topological physics, attosecond science, and valleytronics, advancing ultrafast topotronic control beyond static band engineering.

Keywords: Floquet topological insulator; Light-dressing; Graphene; Femtosecond laser; Coherent control