\textit{In situ} isotopic enrichment and growth of $^{28}$Si for quantum information

Starting from natural abundance silane gas, we deposit $^{28}$Si films enriched \textit{in situ} to 99.9{\%} in support of solid state quantum information systems. Isotopically enriched materials such as $^{28}$Si are known to act as a ``solid state vacuum'' allowing for qubits with coherence (T$_{2})$ times of minutes. Quantum coherent devices rely on long T$_{2}$ times, but nuclear spin impurities are a major cause of decoherence. Isotopically enriching materials to eliminate stray nuclear spins (such as the 4.7{\%} $^{29}$Si in natural silicon) greatly improves coherence. Our objective is to produce silicon that is not only isotopically enriched, but chemically pure and defect free. We crack and ionize a natural abundance source gas, magnetically mass filter the ions in a beam line, and deposit the enriched material hyperthermal energies. In addition to our first $^{28}$Si samples assessed by SIMS to be enriched to \textgreater\ 99.9{\%}, we previously implanted $^{22}$Ne enriched at 99.4{\%} (9.2{\%} natural abundance) as proof of principle and have also grown $^{12}$C films enriched at \textgreater\ 99.996{\%} (98.9{\%} natural abundance). To our knowledge, no other effort is actively producing enriched solid silicon directly from natural abundance silane. Ongoing improvements are leading us towards our goal of $^{28}$Si enriched to \textgreater\ 99.99{\%} and epitaxial deposition.