Compound Josephson-junction coupler for flux qubits with minimal crosstalk
R. Harris, Trevor M. Lanting, A. J. Berkley, Jonas Johansson, Mark W. Johnson, P. Bunyk, E. Ladizinsky, N. Ladizinsky, T. Oh, Siyuan Han · Physical Review B · 2009
An improved tunable coupling element for building networks of coupled rf-superconducting quantum interference device (rf-SQUID) flux qubits has been experimentally demonstrated. This new form of coupler, based on the compound Josephson-junction rf-SQUID, provides a sign and magnitude tunable mutual inductance between qubits with minimal nonlinear crosstalk from the coupler tuning parameter into the qubits. Quantitative agreement is shown between an effective one-dimensional model of the coupler's potential and measurements of the coupler persistent current and susceptibility.