We have demonstrated the enhancement of spin coherence and spin-optical properties of chromium (IV)-based molecular qubits through engineering of the host matrix. Through fluorination of the host matrix of the molecule, we created a non-isostructural environment with lower symmetry, leading to noise-insensitive clock transitions caused by a non-zero transverse zero field splitting.  We measured a spin coherence time of 10 μs, a fivefold improvement from the molecule in an isostructural host. We modeled the coherence properties using cluster correlation expansion methods and demonstrated agreement with experimental coherence measurements for four distinct molecular structures. Furthermore, we explored pathways to optimizing the spin-optical interface in molecular qubits by investigating the key parameters of optical linewidth and spin-lattice relaxation time. Our results show promise for using molecular spin qubits for nanoscale quantum sensing in noisy environments, through a combination of chemical design, qubit measurement and first-principles theoretical calculations.

To learn more, please see: S. L. Bayliss, P. Deb, D. W. Laorenza, M. Onizhuk, G. Galli, D. E. Freedman, and D. D. Awschalom, Physical Review X 12, (2022).