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 at the macroscopic scale 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 and 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 been proposed to be the cause of what limits how well electron microscopes can see. The nearby electron microscope walls destroy the useful quantum mechanical properties of the electrons. If this “decoherence” can be overcome, this may point the way to improving electron microscopes, a widely used scientific tool including in the field of nano-medicine. A second objective of the research team is to look at the “quantumness” of a group of electrons close to each other. This situation exchanges the electron interaction with the wall for the interaction between an electron and electron. It is predicted that this quantumness can be used to further improve the resolution of electron microscopes. The research project will provide experience to postdocs, graduate students, undergraduate students and high school students in quantum science, which is an area of national need. Patents, based on the technologies being developed, will be pursued and will potentially contribute to the national economy. 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. A femtosecond laser will be used to extract multiple electron from a nanotip, that is, make an electron pulse. This will ensure that the electrons are close enough together to interact. The research team will search for a quantum mechanical signature called the Hanbury-Brown Twiss effect by controlling the time duration, the size, and the polarization of the electron pulse. 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.