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Four-qubit device with mixed couplings

M. Grajcar·A. Izmalkov·S. H. W. van der Ploeg·S. Linzen·T. Plecenik·Th. Wagner·U. Huebner·E. Il'ichev·H. -G. Meyer·A. Yu. Smirnov·Peter J. Love·Alec Maassen van den Brink·M. H. S. Amin·S. Uchaikin·A. M. Zagoskin
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Abstract

We present the first experimental results on a device with more than two superconducting qubits. The circuit consists of four three-junction flux qubits, with simultaneous ferro- and antiferromagnetic coupling implemented using shared Josephson junctions. Its response, which is dominated by the ground state, is characterized using low-frequency impedance measurement with a superconducting tank circuit coupled to the qubits. The results are found to be in excellent agreement with the quantum-mechanical predictions.

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M. Grajcar, A. Izmalkov, S. H. W. van der Ploeg, S. Linzen, T. Plecenik, Th. Wagner, U. Huebner, E. Il'ichev, H. -G. Meyer, A. Yu. Smirnov, Peter J. Love, Alec Maassen van den Brink, M. H. S. Amin, S. Uchaikin, A. M. Zagoskin. 2006-02-03. Four-qubit device with mixed couplings. https://doi.org/10.1103/physrevlett.96.047006

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