Molecular Color Centers for Quantum Technologies

Daniel W. Laorenza | Sam L. Bayliss | Peter J. Mintun | Berk Kovos | Arailym Kairalapova | Tamar Goldzak | Samuel M. Greene | Leah R. Weiss | Pratiti Deb | David D. Awschalom  |Timothy C. Berkelbach | Danna E. Freedman

Creating atomically precise spin-bearing quantum bits (qubits) from the bottom up offers a potentially transformative methodology for the design of systems such as nanoscale sensors or multiqubit network nodes. Molecular systems offer the desired Angstrom-scale synthetic control but typically lack mechanisms to optically initialize and read out the ground state spin, hindering their integration into the existing quantum ecosystem. To target optically addressable molecular qubits, we translated the electronic structure of defect-based spins that host this optical-spin interface into three spin-triplet Cr(IV) complexes. We demonstrated optical-spin initialization, coherent ground-state spin control, and optical readout for ensembles of these compounds, indicating that this design approach offers a generalized platform for creating optically addressable molecular spins. Subsequent experimental and theoretical comparison of two classes of Cr(IV)-based molecules demonstrated the impact of the ligand field around the central Cr(IV) ion on both the ground-state spin structure and emission properties. Our results illustrate that these synthetically flexible candidate qubits offer a platform to realize designer molecular color centers for quantum information science.

Funding Sources: DOE | ARO