Coherent Electron Control

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The theory of Quantum Mechanics tells us how electrons, atoms, and all particles that make up matter, behave at a microscopic scale. The theory of Classical Mechanics tells us how bridges, cars, and all parts that make up the objects in our everyday world, behave at a macroscopic scale. Unifying the two in a smooth way, to arrive at a consistent theory of both the microscopic and macroscopic scales is an unsolved problem (the "Quantum Measurement Problem") that has perplexed scientists for about one century. 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. Electrons are placed close to a controllable amount of material in a wall, so that the description of how the two interact is neither easily described by Quantum Mechanics, nor Classical Mechanics. The best provisional description available, which is called decoherence theory, can be tested to its limits 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, electron devices can be constructed that measure small changes in magnetic fields, and may thus assist, for example, in the detection of submerged submarines that distort the Earth's magnetic field. Nanofabricated gratings are used as devices that split electron beams into two parts. These two parts are recombined and show quantum mechanical interference. Walls of doped silicon, gold, and other materials such as graphene and superconductive materials will be placed close to the electron beams used to decohere the electron beams, which causes the quantum mechanical interference to disappear. Four different existing microscopic theories can be tested by the experimental data that will be collected; decoherence theory is an integral part of all four. The knowledge 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 will be attempted to construct the largest and most sensitive electron interferometer in the world. This research project provides experience to graduate students, undergraduate students and high school students in the new research area of free electron quantum optics.