A New Approach to Coherent Neutron Optics and Their Applications

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An interferometer merges two or more sources of light to create an interference pattern, which can be measured and analyzed. Neutron interferometers are exquisite manifestations of quantum coherence. They provide a unique opportunity for precision studies on fundamental questions of nature and neutron interactions with matter and material properties. ******My proposal exploits coherent control of neutron wave function and neutron interferometry to study: 1) quantum information science, 2) condensed matter and magnetic materials, and 3) fundamental questions in physics. ******1. The development of quantum information processing for quantum computation and communication has pushed the need for new methods of coherent control and provides a framework for designing new measurements. Neutron Interferometry provides a robust testbed for implementing quantum manipulations and strong measurements. In the studies proposed here, I will use neutron interferometry to explore coherent control where strong measurements are possible, and I will use quantum information theory to improve the precision and robustness of neutron interferometry-based measurements. ******2. Recent discoveries of novel materials and the control of orbital angular momentum (OAM) prompted new developments in the field of spin-related electronics (spintronics) and quantum devices. Because neutrons are penetrative and their quantum phase is integrated over their path, I plan on using the spin-dependent interferometry as an in-situ and direct measurement of the magnetic properties of functional devices and materials. I anticipate that this new capability will enable greater insight into the function and design of spintronics. In addition, we have recently developed new methods for producing and using neutron OAM. This opens a wide range of possibilities to directly study helical and chiral materials. ******3. Quantum mechanics is used to explain many observable phenomena. However, many basic axioms of quantum physics have not been experimentally verified. The neutron interferometer is an ideal tool to perform those studies, such as the verification of Born's Rule. Another aspect where neutron interferometry techniques will flourish is fundamental physics. For example, the dark energy, which is proposed to explain the accelerated expansion of the universe, is not well understood. A chameleon scalar field, one of the candidates for dark energy, is almost impossible to detect using sensitive gravity tests due to its non-linear coupling to environmental local mass density. Recently, we used neutron interferometry to set the most stringent neutron limit on the coupling strength between the chameleon scalar field and local mass. With our recent demonstration of a grating interferometer based on the universal moiré effect, we have access to a large area and high neutron flux that will enable high precision measurements of forces, such as gravity.