Hydrodynamic electron flow is the intriguing and elusive phenomenon where electrons behave almost like a classical viscous fluid. Recent experimental progress has made it possible to study the intricate properties of charged viscous fluids in various compounds, with and without a magnetic field. We study the ballistic-to-hydrodynamic crossover analytically and numerically to hopefully explain experimental observations and in order to discover new ways to probe electronic correlations.

Beyond linear order, the electrical conductivity still holds many surprises. For example, we recently showed that Landau's Fermi liquid paradigm breaks down beyond linear response. It is our goal to explore and classify nonlinear effects to make them applicable in the characterization quantum materials and detection of ordered states.

Stacking a few layers of graphene on top of each other in various ways reveals an almost unimaginable multitude of metallic, topological and correlated states. Exploring this richness is a major research focus in our group.

Band structure topology has been a main driving force in condensed matter research in the last years. But there is more. We explore the consequences of the local quantum geometry of the electronic ground state, revealing in unprecedented detail the intimate connection between Hilbert space geometry and the wave function in real space.