Tunable coupling of superconducting qubits

Alexandre Blais, Alec Maassen van den Brink, A. M. Zagoskin

Published 2002-07-03, updated 2003-03-18Version 3

We study an LC-circuit implemented using a current-biased Josephson junction (CBJJ) as a tunable coupler for superconducting qubits. By modulating the bias current, the junction can be tuned in and out of resonance and entangled with the qubits coupled to it. One can thus implement two-qubit operations by mediating entanglement. We consider the examples of CBJJ and charge--phase qubits. A simple recoupling scheme leads to a generalization to arbitrary qubit designs.