Enhanced coherence by coupling spins through a delocalized π-system: Vanadyl porphyrin dimers

Units of quantum information, called qubits, must communicate with each other if they are to perform useful logic operations. Finding suitable scaffolds for linking chemically synthesized qubits together is crucial for the development of molecular quantum technologies. π-conjugated linkers allow efficient electron transport over relatively long distances, but can they be used to couple together qubits, such as vanadyl ions? In this article, we not only answer affirmatively but also show that conjugated linkers can outperform other types of bridges by preserving the quantum coherence. We synthesize two families of porphyrins containing vanadyl ions and investigate their geometry, conjugation, and quantum performance. The discovery that a π-conjugated backbone can protect from decoherence is valuable for the design of molecular materials for functional quantum devices operated by microwaves and with electrical readout.