[PAST EVENT] Physics Colloquium
September 2, 2011
The exploration of topological phases of matter is one of the main challenges in condensed matter physics. Among the exciting recent developments in this direction are the discoveries of the new phases of matter with many intriguing properties such as topological insulators and superconductors. In this colloquium, I will focus on topological superconductors and discuss how one can engineer non-trivial p-wave superconductivity in the laboratory at the interface of a conventional superconductor and a semiconductor with spin-orbit interaction. I will show that such a topological state emerging at the interface supports zero-energy modes that can be occupied by Majorana fermions. These quasi-particles, which are exotic in the sense that they are at the same time their own antiparticles, are effectively fractionalized objects (anyons) obeying unconventional exchange statistics. Despite being first predicted by E. Majorana in the 1930s, there is still no conclusive evidence of their existence, and the race to discover Majorana fermions is on. If found, Majorana fermions would constitute a key building block for the implementation of fault-tolerant topological quantum computation schemes that are inherently decoherence-free. I will conclude by proposing several experiments for detecting Majorana fermions in one-dimensional nanowires.