Hamiltonian for coupled flux qubits
| dc.creator | Brink, Alec Maassen van den | |
| dc.date | 2003-10-17 | |
| dc.date | 2003-12-12 | |
| dc.date.accessioned | 2026-07-07T02:54:16Z | |
| dc.date.available | 2026-07-07T02:54:16Z | |
| dc.description | An effective Hamiltonian is derived for two coupled three-Josephson-junction (3JJ) qubits. This is not quite trivial, for the customary "free" 3JJ Hamiltonian is written in the limit of zero inductance L. Neglecting the self-flux is already dubious for one qubit when it comes to readout, and becomes untenable when discussing inductive coupling. First, inductance effects are analyzed for a single qubit. For small L, the self-flux is a "fast variable" which can be eliminated adiabatically. However, the commonly used junction phases are_not_ appropriate "slow variables", and instead one introduces degrees of freedom which are decoupled from the loop current to leading order. In the quantum case, the zero-point fluctuations (LC oscillations) in the loop current diverge as L->0. Fortunately, they merely renormalize the Josephson couplings of the effective (two-phase) theory. In the coupled case, the strong zero-point fluctuations render the full (six-phase) wave function significantly entangled in leading order. However, in going to the four-phase theory, this uncontrollable entanglement is integrated out completely, leaving a computationally usable mutual-inductance term of the expected form as the effective interaction. | |
| dc.description | REVTeX4, 16pp., one figure. N.B.: "Alec" is my first, and "Maassen van den Brink" my family name. Informal note. v2: completely rewritten; correction of final result and major expansion. v3: added numerical verification plus a discussion of Ref. [2] | |
| dc.identifier | https://arxiv.org/abs/cond-mat/0310425 | |
| dc.identifier | http://arxiv.org/abs/cond-mat/0310425 | |
| dc.identifier | Phys. Rev. B_71_, 064503 (2005) | |
| dc.identifier | doi:10.1103/PhysRevB.71.064503 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/22479 | |
| dc.subject | Mesoscale and Nanoscale Physics | |
| dc.subject | Superconductivity | |
| dc.title | Hamiltonian for coupled flux qubits | |
| dc.type | text |