Quantum Yellow Trail Star

Graphene beam splitter gives electron quantum optics a boost


+  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 tuneable device’s operation is directly comparable that of an optical interferometer. The technology could soon enable allow electron interferometry to be used in nanotechnology and quantum computing.

From their observations, the team spotted characteristic oscillations in this output current, which varied depending on the voltage and magnetic field strength applied to the first beam splitter. In analogy with the interference patterns seen in recombined interferometer beams, these oscillations indicated the phase differences between the recombined n side currents. The team will now aim to further compact their graphene flake design; potentially leading to new, highly advanced capabilities in both nanotechnology and quantum computing.


+  An optical interferometer splits a beam of light in two, sending each beam a long 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 fact that electrons behave as 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.

Source:  physicsworld.  Sam Jarman,  Graphene beam splitter gives electron quantum optics a boost…

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