Switchable resonant coupling of flux qubits

Physics and Astronomy Dept., The University of British Columbia, Vancouver, V6T 1Z1 Canada(Dated: February 6, 2008)We propose a coupling scheme, where two or more flux qubits with different eigenfrequenciesshare Josephson junctions with a coupler loop devoid of its own quantum dynamics. Switchabletwo-qubit coupling is realized by tuning the frequency of the AC magnetic flux through the couplerto a combination frequency of two of the qubits. The coupling allows any or all of the qubits to besimultaneously at the degeneracy point and can change sign.