MPS/CHE-EPSRC: Nanoscale Spin Entanglement and Chemistry (NanoSPINEC)

With support from the Division of Chemistry, Professor Joel Yuen-Zhou of the University of California San Diego, along with their collaborators from the University of Cambridge in the United Kingdom, are developing nanophotonic platforms to probe quantum spin states in individual organic molecules at room temperature. This collaborative project combines expertise in nanophotonics, organic photophysics, and quantum information science to address longstanding challenges in detecting and controlling quantum correlations in molecular systems. The project leverages nanoparticle-on-mirror (NPoM) nanocavities to enable highly localized optical fields that enhance photon collection and facilitate optical readout of single-molecule spin states. A central goal is to achieve the first room-temperature measurements of molecular spins using optically detected magnetic resonance (ODMR), overcoming previous limitations that required cryogenic conditions. Their discoveries could advance fundamental understanding of quantum entanglement in chemistry, reveal new mechanisms of spin coherence, and establish organic molecules as scalable platforms for quantum technologies. The project will also contribute to workforce development by training graduate students in interdisciplinary techniques spanning quantum optics, molecular spectroscopy, and nanofabrication, supporting the next generation of scientists in the global quantum science community. This award is made under the NSF-UKRI lead agency opportunity. The technical objectives of this project focus on using nanophotonic enhancement to realize single-molecule ODMR, track the formation and decay of entangled triplet-pair states, and demonstrate the first Bell inequalities test in a chemical system. Single-molecule measurements will be enabled by NPoM nanocavities, which provide self-assembled, tunable structures with reproducible sub-nanometer gaps that significantly amplify optical fields. This platform allows sensitive detection of spin-dependent photoluminescence fluctuations, revealing molecular spin dynamics under ambient conditions. The team will integrate fluctuation spectroscopy, single-photon detection, and microwave spin control to extract ODMR spectra and coherence properties at the single-molecule level. The project will also investigate singlet fission and triplet-triplet annihilation processes within the NPoM platform to monitor quantum correlations between triplet states and explore entanglement loss dynamics. Finally, by combining ODMR with tailored microwave rotations and spin-selective photophysics, the researchers aim to perform a molecular-scale Bell test, providing direct evidence of quantum nonlocality in chemical systems. These efforts will advance understanding of spin chemistry and lay the foundation for scalable, room-temperature molecular qubits in quantum information science. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.