Flux qubit in charge-phase regime

A superconducting qubit implementation is proposed that takes advantage of both charge and phase degrees of freedom. Superpositions of flux states in a superconducting loop with three Josephson junctions form the states of the qubit. The charge degree of freedom is used to read out and couple the qubits. Cancellation of first-order coupling to charge and flux fluctuations, at the working point of the qubit, protects it from the dephasing due to these sources.