It has often been assumed that electrically floating qubits, such as flux qubits, are immune to decoherence due to capacitive coupling. We show that capacitive coupling to bias leads can be a dominant source of dissipation, and therefore of decoherence, for such floating qubits. Classical electrostatic arguments are sufficient to get a good estimate of this source of relaxation for standard superconducting qubit designs. We show that relaxation times can be improved by designing floating qubits so they couple symmetrically to the bias leads. Observed coherence times of flux qubits with varying degrees of symmetry qualitatively support our results.
@article{arxiv.0807.4535,
title = {Decoherence of floating qubits due to capacitive coupling},
author = {Matthias Steffen and Frederico Brito and David DiVincenzo and Shwetank Kumar and Mark Ketchen},
journal= {arXiv preprint arXiv:0807.4535},
year = {2009}
}
Comments
V1: 4 pages, 3 figures. V2: 5 pages, 3 figures. Published version