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arXiv · 1011.6148

Quantum dynamics of a dc-SQUID coupled to an asymmetric Cooper pair transistor

A. Fay·W. Guichard·O. Buisson·F. W. J. Hekking
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Abstract

We present a theoretical analysis of the quantum dynamics of a superconducting circuit based on a highly asymmetric Cooper pair transistor (ACPT) in parallel to a dc-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 micron-size 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 regimes. It describes very precisely the tunable coupling strength measured in this circuit and explains the 'quantronium' as well as the adiabatic quantum transfer read-out.

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A. Fay, W. Guichard, O. Buisson, F. W. J. Hekking. 2010-11-29. Quantum dynamics of a dc-SQUID coupled to an asymmetric Cooper pair transistor. https://arxiv.org/abs/1011.6148

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