Coherent Electron Control

University Of Nebraska-Lincoln, Lincoln NE

Investigators

Abstract

Classical Mechanics tells us how bridges, cars, and other objects in our everyday world work. Quantum Mechanics tells us how electrons, atoms and other objects in the microscopic world work. We need to find a description of nature that works at the microscopic and macroscopic scales and everything in between. This is a century-old unsolved problem that is called the "Quantum Measurement Problem." Not only do we want to solve the problem, but we want to use "quantumness" at a larger scale, and not understanding the problem stops us from doing this. To solve this problem objects at an intermediate scale, in between the microscopic and macroscopic, need to be studied. This is what the project: "Coherent Electron Control" is aiming to do. Microscopic objects, electrons, are placed close to an everyday world object, a wall, so that the description of how the two interact is neither described by Quantum Mechanics, nor Classical Mechanics. New models and theories can be tested in this way. On the practical side, the interaction between electrons and walls has stopped the development of sensitive devices based on electrons, called electron interferometers. The walls destroy the useful quantum mechanical properties of the electrons. If this "decoherence" can be overcome, new electron devices can be constructed that measure, for example, small changes in magnetic fields, and may thus find application in the numerous areas of technology where magnetic fields play a key role. Electron diffraction from nanofabricated gratings will be used to split electron beams coherently into two parts. Walls will be placed close to the electron beams to partially decohere the electron beams. The electron beams are recombined and the measured amount of quantum mechanical interference tells us about the amount of decoherence. Four different existing microscopic theories have now been tested. Control of the decoherence will be explored by changing the wall from insulating copper oxide, to semi-conducting Gallium Arsenide, to conducting gold, and illuminating the walls with laser light and particles. The understanding gained will be used to control and reduce the decoherence and be applied to enlarge the size of existing electron interferometers. In this way it is attempted to construct the largest and most sensitive electron interferometer in the world. Patents will be pursued based on the new technology being developed and the inventions may be marketable. The research project provides experience to graduate students, undergraduate students and high school students in the new research area of free electron quantum optics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.