Forming a Two-Qubit System from Dimers of Molecular Nanomagnets

Molecular nanomagnets (MNMs) are a class of materials that can make good spin qubit candidates due to their chemical engineerability. We present a method for constructing two-qubit gates using dimers of Cr₇Mn, a spin S=1 MNM that features a zero-field clock transition. Operating at this transition increases T₂, allowing for more gates during the lifetime of the quantum state. We show that such a dimer system can be used to behave as a two-qubit system in which all of the transitions between states are clock transitions. One-qubit gates can be achieved using pulsed electron-spin resonance, and two-qubit gates can be implemented using an always-on exchange interaction between the molecules of the dimer. After truncating the Hamiltonian to its four lowest-energy states and transforming into the interaction picture, we simulated both a one-qubit gate as well as a CNOT gate sequence that has a duration of 85 ns, finding average fidelities of 99.5% for both gates. We will briefly discuss ongoing work to experimentally implement these protocols.