Quantum Mechanics, Identical Particles, and the Strange Case of Anyons

Electrons are indistinguishable particles - you cannot tell one electron from another by the color of its hair, or the shape of its ears, or the way it laughs. A basic tenet of quantum mechanics is that all elementary particles are either bosons or fermions, distinguished by their quantum statistics. Loosely speaking, bosons are social animals who like to flock together while fermions are solitary creatures that tend to avoid each other’s company. Ensembles of bosons or fermions behave differently due to differences in their underlying quantum statistics. Starting in the late 1970s it was theoretically conjectured that excitations that are neither bosons nor fermions may exist under special conditions in two-dimensional interacting electron systems. These unusual excitations were dubbed "anyons." Anyons may possess fractional charges and fractional statistics. However, directly probing these properties presents experimental challenges. This lecture will focus on the development of electronic Fabry-Pérot interferometers that resulted in the first direct observation of anyonic braiding statistics for the fractional quantum Hall state at n=1/3. These experiments demonstrate that ensembles of fundamental particles confined to reduced dimensions may act in concert to form new excitations with properties unlike anything previously observed in nature.

Speaker: Michael Manfra, Purdue University