Duke Physics Colloquium: Topological Phases, Qubits, Decoherence and All That

"Topological Phases, Qubits, Decoherence and All That" - Topological matter now is one of the most intensely explored topics in condensed matter physics. Topological phases are theoretically conjectured to occur in an astonishingly vast array of different material systems with a wide range of physical properties predicted - a subset of which may even be useful! Intriguingly, certain topological phases may harbor low energy excitations with exotic braiding statistics. When traversing closed trajectories around one another, these excitations behave not as fermions or bosons, but altogether differently, and have given a rather obscure appellation - non-Abelian anyons. Theory suggests that quantum information can be stored and manipulated in these usual beasts. I will describe our attempts to build and interrogate such topological phases in semiconductor and semiconductor-superconductor hybrid devices. We study phenomena ranging from the fractional quantum Hall effect in ultra-high mobility gallium arsenide to proximity-induced superconductivity in semiconductors with strong spin-orbit coupling - a system that may mimic topological superconductivity. I will focus on basic physical principles underlying device operation, illustrated with a few key examples. The potential utility of such systems for quantum computing will also be discussed. Faculty host: Harold Baranger | Refreshments will be available in room 130 before the event.