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arXiv:1205.6375 · Applied Physics Letters

Frequency division multiplexing readout and simultaneous manipulation of an array of flux qubits

Markus Jerger, Stefano Poletto, P. Macha, Uwe Hübner, Evgeni V. Il’ichev, Alexey Vladimirovich Ustinov

Published Jul 23, 2012• 98 citations
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Abstract

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 manipulation and time resolved measurement of 3 qubits. We discuss how this technique can be scaled up to read out hundreds of qubits on a chip.

DOI
10.1063/1.4739454

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As the field of quantum computing progresses to larger-scale devices, multiplexing will be crucial to scale quantum processors. While multiplexed readout is common practice for superconducting devices, relatively little work has been reported about the combination of flux and microwave control lines. Here, we present a method to integrate a microwave line and a flux line into a single “XYZ line.” This combined control line allows us to perform fast single-qubit gates as well as to deliver flux signals to the qubits. The measured relaxation times of the qubits are comparable to state-of-the-art devices employing separate control lines. We benchmark the fidelity of single-qubit gates with randomized benchmarking, achieving a fidelity as high as 99.93±0.04%, and we demonstrate that XYZ lines can in principle be used to run parametric entangling gates.
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