Vidya Madhavan
University of Illinois, Urbana-Champaign
Creating and Measuring the Elusive Majorana Fermions
Location: 1080 Physics Research Building
Faculty Host: Mohit Randeria
Abstract: Dirac’s theory established that every fundamental particle must have a distinct antiparticle carrying the opposite charge, with the two annihilating upon meeting. In 1937, Ettore Majorana predicted a remarkable class of fermions in which the particle and antiparticle are identical. Except for the possible case of neutrinos, no fundamental particles of this type have been confirmed.
In recent years, the prospect of realizing Majorana fermions as quasiparticle excitations in solids has generated great excitement. While most efforts have focused on localized Majorana bound states as potential building blocks for topological qubits, Majorana fermions can also propagate with linear dispersion, much like elementary particles. These propagating modes could open new pathways for quantum information processing.
This talk will highlight recent progress in engineering Majorana modes within condensed matter systems possessing nontrivial topological properties. I will first outline the theoretical conditions for realizing such states and their expected experimental signatures. I will then discuss two promising platforms: bulk topological superconductors and proximitized topological insulators, where an effective time-reversal-invariant analog of p+ip superconductivity can emerge. Finally, I will present low-temperature scanning tunneling microscopy results on two representative systems: FeSexTe1-x believed to be an intrinsic proximitized topological insulator, and UTe2, a candidate bulk topological superconductor.