The world in the midst of a quantum computing race - one that will result in groundbreaking computing power that far surpasses the performance of digital supercomputers. Quantum computing has the potential to fundamentally change commerce, intelligence, military affairs and the global balance of power. There is a great deal of investment in quantum computing research worldwide, which is producing a surge of breakthroughs in quantum physics technology. Current projection are that quantum computers will be available within the next 3 to 5 years that have the promised disruptive computing power. Nuclear-spin-free silicon crystals would be an ideal host matrix to place magnetic quantum bits q-bits) for quantum-computing and quantum-sensing applications. Polycrystalline nuclear-spin-free Si wafers would allow the immense base of semiconductor fabrication technology to be employed to create quantum computers. The absence of nuclear spin in the host matrix is required in order to avoid disruption of the quantum bits. Naturally occurring silicon Si, atomic number 14) is composed of three stable isotopes: 28Si 92.23%), 29Si 4.67%), and 30Si 3.10%). 29Si has a nuclear spin while 28Si and 30Si do not and so 29Si must be removed down to the part per million level. Currently there is no capability for cost-effective large scale enrichment of 28Si. The goal of the proposed work is to develop a novel approach to silicon isotope separation that will use the difference in reactivity of the three naturally-occurring silicon isotopes. The 'magnetic isotope effect' will be employed to differentially react 29Si from 28Si and 30Si. The difference in reactivity will be used to either directly deplete 29Si to the required sub-ppm levels or deplete 29Si sufficiently to facilitate final purification with distillation or centrifugation. In Phase 1 we will develop a method of separating the 29Si isotope from the 28Si and 30Si isotopes in an isotopic mixture of Si by generating and reacting a radical molecular species that includes one or more Si atoms Si) in a magnetic field. The silicon radical is created by splitting the Si-Si bond in disilane, H3Si-SiH3, to form H3Si. The H 29Si radical preferentially reacts with another H 29Si to form H 29Si-29SiH in preference to the other isotopes. During Phase I, SFQS will 1) build a testbed reactor with a magnetic field with photolysis and reaction capabilities, 2) characterize the degree of reactivity difference in H3Si isotopes, and 3) investigate other radical species, R 29Si, where R = methyl, alkyl, aryl, vinyl, etc. The optimized chemistry developed in Phase I will inform the design of a continuous reactor and separator in Phase II. The proposed work will lay the foundation for commercial production of polycrystalline nuclear- spin-free silicon wafers. The technology is anticipated to be at least an order of magnitude lower cost than centrifugation or distillation alternatives. Immediately the availability of research quantities of nuclear-spin-free silicon wafers will allow researchers to develop silicon-based quantum bits. Ultimately this will allow semiconductor fabrication technology to be used to create quantum computers. The market opportunity being addressed is to supply nuclear-spin-free silicon wafers to the quantum computing and quantum sensing markets.
