Computational search of transition-metal-doped cyrstals for spin-light interfaces*

Transition metal ions in semiconductors are one of the solid-state platforms currently being explored for quantum information science and technology applications, but given the millions of potential ion-host combinations, an experimental screening of all transition-metal-doped crystals would be prohibitive. To limit this plethora of possibilities, and to identify ion-host systems best suited to specific applications, this is a field that welcomes computational tools that integrate the many relevant physical characteristics of each ion-host combination, together with methods to estimate their spin and optical properties.

Here, we present a set of tools developed to estimate the physical properties of ions in crystals that integrates: group theory to take into account the symmetry of the crystal host; an implementation of crystal-field theory to provide an approximation to energy levels and transition rates; curated databases of relevant atomic, spectroscopic, crystallographic, and nuclear data; a set of heuristics that expands the scope of the approach at the expense of precision; and a set of experimental constraints that offers the possibility of finding systems not only useful in principle but also of practical relevance.

This approach seeks to summarize and extend decades of research into the properties of ions in crystals, and as a specific example of how it can be used to guide the way in finding materials systems for quantum technologies, we will define a set of metrics relevant for spin-light interfaces, and offer a list of ion-host systems that might be of future relevance.