Scaling Up Molecular Electron Spin Qubits Around a Core-Shell Quantum Dot.

Attachment of molecular nanomagnets (MNMs) to surfaces is an essential step toward multi-qubit assemblies for the implementation of quantum information technologies. Here, thiol-monofunctionalized {Cr7Ni} molecular antiferromagnetic rings that have potential as electron spin qubits have been synthesized and successfully attached to the surface of a highly luminescent core-shell CdSe/ZnS quantum dot (QD) nanoparticle via a ligand exchange process. The successful grafting of eleven molecular rings per QD was confirmed by high-angle annular dark field (HAADF) scanning transmission electron microscope (STEM) imaging, energy dispersive x-ray (EDX) imaging, and dynamic light scattering (DLS) measurements. Photoluminescence (PL) and pulse electron paramagnetic resonance (EPR) spectroscopies indicated that the resulting hybrid nano-objects display the bright optical emission provided by CdSe/ZnS QDs and long-lived quantum coherence associated with eleven grafted {Cr7Ni} molecular qubits. Thus, grafting of MNMs to nanoparticle surface provides an elegant method for generating hybrid assemblies with magnetic optical dual functionality and a facile approach to scale electron spin qubits.