An important desired ingredient of superconducting quantum circuits is a readout scheme
whose complexity does not increase with the number of qubits involved in the measurement.
Here, we present a readout scheme employing a single microwave line, which enables
simultaneous readout of multiple qubits. Consequently, scaling up superconducting qubit
circuits is no longer limited by the readout apparatus. Parallel readout of 6 flux qubits using a
frequency division multiplexing technique is demonstrated, as well as simultaneous …