CAPACITIVE COUPLING FOR FLUX QUBITS

Current quantum annealers based on flux qubits feature only inductive coupling, resulting in a ZZ interaction (where Z is the computational basis). For future quantum annealers to solve problems which are out of the reach of the classical quantum Monte Carlo algorithm, qualitatively different interactions are additionally required. One such interaction is the YY interaction which can be implemented by capacitive coupling between the charge degree of freedom for flux qubits. We will design, fabricate and characterise a voltage-tuneable non-linear capacitive coupler for flux qubits based on the single Cooper-pair transistor.