Superconducting charge qubits from a microscopic many-body perspective
- Resource Type
- Working Paper
- Authors
- Rodrigues, D. A.; Spiller, T. P.; Annett, J. F.; Györffy, B. L.
- Source
- J. Phys.: Condens. Matter 19 (2007) 436211.
- Subject
- Condensed Matter - Mesoscale and Nanoscale Physics
Condensed Matter - Superconductivity
Quantum Physics
- Language
The quantised Josephson junction equation that underpins the behaviour of charge qubits and other tunnel devices is usually derived through cannonical quantisation 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 quantised 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.
Comment: Accepted for J Phys Condensed Matter