Efficient evaluation of decoherence rates in complex Josephson circuits
Abstract
A complete analysis of the decoherence properties of a Josephson junction qubit is presented. The qubit is of the flux type and consists of two large loops forming a gradiometer and one small loop, and three Josephson junctions. The contributions to relaxation (T_1) and dephasing (T_\phi) arising from two different control circuits, one coupled to the small loop and one coupled to a large loop, is computed. We use a complete, quantitative description of the inductances and capacitances of the circuit. Including two stray capacitances makes the quantum mechanical modeling of the system five dimensional. We develop a general Born-Oppenheimer approximation to reduce the effective dimensionality in the calculation to one. We explore T_1 and T_\phi along an optimal line in the space of applied fluxes; along this "S line" we see significant and rapidly varying contributions to the decoherence parameters, primarily from the circuit coupling to the large loop.
Keywords
Cite
@article{arxiv.cond-mat/0510843,
title = {Efficient evaluation of decoherence rates in complex Josephson circuits},
author = {David P. DiVincenzo and Frederico Brito and Roger H. Koch},
journal= {arXiv preprint arXiv:cond-mat/0510843},
year = {2007}
}
Comments
16 pages, 20 figures; v2: minor revision