High-purity solid parahydrogen

Alkali atoms trapped in solid hydrogen matrices have demonstrated ultralong electron spin coherence times and are promising as quantum sensors. Their is limited by magnetic noise from naturally occurring orthohydrogen molecules the parahydrogen matrix. In gas phase, component of can be converted to flowing it over a catalyst held at cryogenic temperatures, with lower temperatures giving fraction. this work, we use single cryostat reduce fraction grow matrix resulting high-purity parahydrogen. We demonstrate operation down temperature 8 K, spectroscopically verify that impurities level <10−6. also find that, sufficiently low provides isotopic purification, reducing HD