Singlet fission, a process that splits a singlet exciton into a biexciton, has promise in quantum information. We report time-resolved electron paramagnetic resonance measurements on a molecule, TIPS-BP1′, designed to exhibit strongly state-selective relaxation to specific magnetic spin sublevels. The resulting optically pumped "spin polarization" is a nearly pure initial state from the ensemble. The long-lived spin coherences modulate the signal intrinsically, allowing a new measurement scheme that substantially removes noise and uncertainty in the magnetic resonance spectra. A nonadiabatic transition theory with a minimal number of spectroscopic parameters allows the quantitative assignment and interpretation of the spectra. The rigid, covalently bound dimer, TIPS-BP1′, supports persistent spin coherences at temperatures far higher than those used in conventional quantum hardware.
@article{arxiv.2202.09678,
title = {Entangled, Spin-polarized Excitons from Singlet Fission in a Rigid Dimer},
author = {Ryan D. Dill and Kori E. Smyser and Niels H. Damrauer and Joel D. Eaves},
journal= {arXiv preprint arXiv:2202.09678},
year = {2022}
}