Superconducting charge qubits from a microscopic many-body perspective

D. A. Rodrigues*, T. P. Spiller, J. F. Annett, B. L. Györffy

*Corresponding author for this work

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The quantized Josephson junction equation that underpins the behaviour of charge qubits and other tunnel devices is usually derived through canonical quantization of the classical macroscopic Josephson relations. However, this approach may neglect effects due to the fact that the charge qubit consists of a superconducting island of finite size connected to a large superconductor. We show that the well-known quantized Josephson equation can be derived directly and simply from a microscopic many-body Hamiltonian. By choosing the appropriate strong-coupling limit we produce a highly simplified Hamiltonian that nevertheless allows us to go beyond the mean-field limit and predict further finite-size terms in addition to the basic equation.

Original languageEnglish
Article number436211
JournalJournal of physics : Condensed matter
Issue number43
Publication statusPublished - 31 Oct 2007

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