Researchers at MIT, NIST, University of Maryland, Imperial College London, and the National Institute for Materials Science (NIMS) in Japan have created a "whispering gallery" effect for electrons in a sheet of graphene, making it possible to precisely control a region that reflects electrons within the material. This accomplishment could help in heralding new kinds of electronic lenses, as well as quantum-based devices that combine electronics and optics.
The process uses a probe (the same as in STM - Scanning Tunneling Miscroscopy) that allows control of both the location and the size of the reflecting region within graphene. When the sharp tip is positioned over a sheet of graphene, it produces a circular barrier on the sheet that "acts as a perfect curved mirror" for electrons, according to the scientists, reflecting them back toward the center of the circle. This controllable reflectivity is similar to so-called "whispering gallery" confinement modes that have been used in optical and acoustic systems - but these have not been tunable or adjustable.Since the method is based on well-understood STM technology, it could be developed relatively quickly into usable devices. The STM not only creates the whispering gallery effect, but also provides a means of observing the results, to study the phenomenon.