Quantum Circulators Simplified

The superconducting qubit is a leading candidate for building a quantum computer. So far, however, quantum circuits with only a small number of such qubits have been demonstrated. As researchers scale up the qubit number, they need devices that can route the microwave signals with which these qubits communicate. Benjamin J. Chapman at JILA, the University of Colorado, and the National Institute of Standards and Technology, all in Boulder, Colorado, and co-workers have designed, built, and tested a compact on-chip microwave circulator that could be integrated into large qubit architectures.