Asymmetric Cooper pair transistor in parallel to a dc SQUID: Two coupled quantum systems

A. Fay*, W. Guichard, O. Buisson, F. W.J. Hekking

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    3 Citations (Scopus)

    Abstract

    We present a theoretical analysis of a superconducting quantum circuit based on a highly asymmetric Cooper pair transistor (ACPT) in parallel to a dc superconduction quantum intereference device (SQUID). Starting from the full Hamiltonian we show that the circuit can be modeled as a charge qubit (ACPT) coupled to an anharmonic oscillator (dc SQUID). Depending on the anharmonicity of the SQUID, the Hamiltonian can be reduced either to one that describes two coupled qubits or to the Jaynes-Cummings Hamiltonian. Here the dc SQUID can be viewed as a tunable micrometer-sized resonator. The coupling term, which is a combination of a capacitive and a Josephson coupling between the two qubits, can be tuned from the very strong- to the zero-coupling regime. It describes very precisely the tunable coupling strength measured in this circuit and explains the "quantronium" as well as the adiabatic quantum transfer readout.

    Original languageEnglish
    Article number184510
    JournalPhysical Review B (Condensed Matter and Materials Physics)
    Volume83
    Issue number18
    DOIs
    Publication statusPublished - 17 May 2011
    MoE publication typeA1 Journal article-refereed

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