Splitting up: schematic of the electron beam splitter with the n side on the right and the p side on the left. (Courtesy: M Jo et al/Phys. Rev. Lett.)
Topics: Graphene, Interferometry, Nanotechnology, Quantum Computer
A graphene-based “beam splitter” for electronic currents has been built by researchers in France, South Korea, and Japan. Created by Preden Roulleau at the University of Paris and colleagues, the tunable device’s operation is directly comparable to that of an optical interferometer. The technology could soon enable allow electron interferometry to be used in nanotechnology and quantum computing.
An optical interferometer splits a beam of light in two, sending each beam along a different path before recombining the beams at a detector. The measured interference of the beams at the detector can be used to detect tiny differences in the lengths of the two paths. Recently, physicists have become interested in doing a similar thing with currents of electrons in solid-state devices, taking advantage of the fact that electrons behave like waves in the quantum world.
Graphene is a sheet of carbon just one atom thick and is widely considered to be the best material for realizing such “electron quantum optics”. Indeed, researchers have already used the material to make simple electron interferometers. Now, Roulleau’s team has created a fully adjustable electron beam splitter that could be used to build more sophisticated devices. It exploits the quantum Hall effect, whereby the application of a strong magnetic field perpendicular to a sheet of graphene will cause an electron current to flow around the edge of the sheet.
Graphene beam splitter gives electron quantum optics a boost, Sam Jarman, Physics World
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