Optically-addressable molecular qubits are a new frontier in the study of materials-based quantum bits. They provide a promising scalable platform for quantum technology, and have exceptional scalability tunability via chemical synthetic control and functionalization of the qubit. We demonstrate that controlling the molecular crystal hosting the active qubit is a powerful means for enhancing coherence. By adding Fl to the tin-based matrix supporting a Cr molecular qubit, Awschalom and Freedman (with theory input from Galli) were able to create a a qubit whose energy splitting is first-order insensitive to changes in magnetic field. This dramatically increases coherence time by a factor of 5 (from 2 to 10 us). (a) Schematic showing two different host matrices, (b) T2 coherence time for each structure.
