Quantum Logic with Prototype Molecular Spin-Qubits

This project will concentrate on synthesising a library of new molecular qubits and linking these through coordination chemistry to assemble prototype two- and three-qubit gates. The spin-qubit manifests as a coordination complex with a diamagnetic transition metal bound by a redox-active dithiolene ligand which can be readily oxidised chemically or electrochemically to generate unpaired spins. A redox-inert tetraphosphine ligand will bridge two metallodithiolene units, and their subsequent oxidation generates two weakly coupled spins - a two-quit system. The weak coupling is essential so that the molecule can be physically addressed to access the triplet state. The project begins with the preparation of a series of dimetallic complexes with different the metal ions, dithiolene substituents and diphosphine bridge structure to modulate the electronic coupling. Advanced spectroscopic characterisation and theoretical studies will define the optimal composition for two-qubit gating. The synthetic motif will be extended to incorporate switchable functionalities where unpaired spins can be generated for a finite period of time to create a variety of spin states. The switch will be accessed via an external stimulus, using light, magnetic fields, or electricity. Testing of these prototypical two- and three-qubit gates will facilitate a deeper understanding of the fundamental requirements for quantum computing.