UNSW seminar: Topology and transport in interacting electron systems

Prof Thomas Schmidt

Prof Thomas Schmidt, University of Luxembourg, Friday 5 May 2023 at the UNSW Physics building

Coulomb interactions between electrons can give rise to a plethora of novel phenomena in solid-state systems. In this talk I will focus on two phenomena which are caused by the interplay of interactions and band topology in two-dimensional electron systems.

In the semiclassical regime, electron hydrodynamics was recently discovered as a new transport paradigm where strong interactions cause electrons to flow like a viscous fluid. This is a strong contrast to the ballistic or diffusive transport found more commonly in solid-state systems. In the first part of the talk, I will introduce the field of electron hydrodynamics and present our recent results about the effect of band structure topology on viscous electron flow and about the role of electron viscosity on the Coulomb drag in graphene double layers.

Moreover, electron-electron interactions are at the heart of the fractional quantum Hall (FQH) effect. Research over the past years has shown that combining FQH states with superconductors can give rise to parafermionic bound states, a novel type of emergent quasiparticle. In the second part of the talk, I will introduce the concept of parafermions, discuss the systems which could host them, and review recent experimental progress towards realizing them. Moreover, I will discuss possible experimental signatures of parafermions and show how parafermionic bound states can be useful for topologically protected quantum computation.

Thomas Schmidt obtained his PhD in 2008 at the University of Freiburg (Germany). After postdocs at the University of Basel (Switzerland) and Yale University (USA), he joined the University of Luxembourg in 2015 as an ATTRACT fellow of the National Research Fund Luxembourg. Since 2020, he is a full professor at the University of Luxembourg. His research is in the area of mesoscopic quantum systems, in particular interacting electron systems and quantum transport.