Optically Detected Coherent Spin Control of Organic Molecular Color Center Qubits
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2025-06-17 |
| Journal | Journal of the American Chemical Society |
| Authors | Sebastian M. Kopp, Shunta Nakamura, Yong Rui Poh, Kathryn R. Peinkofer, Brian T. Phelan |
| Institutions | University of California, San Diego |
| Citations | 5 |
Abstract
Section titled āAbstractāMolecular optical-spin interfaces are emerging as promising alternatives to solid-state defects, such as diamond nitrogen vacancy centers for quantum information science applications. In this work, we report a new organic molecular color center consisting of two luminescent tris(2,4,6-trichlorophenyl)methyl (<b>TTM</b>) radicals connected at the 2,6-positions of a toluene bridge. Optical polarization of the |T<sub>0</sub>ā© sublevel of the triplet ground state is achieved by spin-selective excited-state intersystem crossing from the |T<sub>+</sub>ā© and |T<sub>-</sub>ā© sublevels of the triplet excited state. Steric hindrance between the toluene methyl group and the phenyls of the <b>TTM</b> radicals results in a structure that increases the excited-state intersystem crossing spin selectivity while reducing the electronic coupling between the <b>TTM</b> subunits. This results in an order of magnitude increase in the optically detected magnetic resonance contrast and longer excited-state lifetimes relative to the sterically unencumbered analogue. We demonstrate coherent microwave manipulation of the spin-polarized ground-state populations and coherences using optical detection of Rabi nutations, Hahn echo formation, and echo decay measurements at 85 K in a nuclear-spin-rich solvent matrix. This marks a crucial step toward leveraging the favorable spin relaxation times of organic molecules for applications as quantum sensors at temperatures that heretofore have been difficult to achieve by molecular color centers.