Cooper pair pumping is a coherent process. We derive a general expression for the adiabatic pumped charge in superconducting nanocircuits in the presence of level degeneracy and relate it to non-Abelian holonomies of Wilczek and Zee. We discuss an experimental system where the non-Abelian structure of the adiabatic evolution manifests in the pumped charge.
@article{arxiv.cond-mat/0702333,
title = {Non-abelian superconducting pumps},
author = {Valentina Brosco and Rosario Fazio and F. W. J. Hekking and Alain Joye},
journal= {arXiv preprint arXiv:cond-mat/0702333},
year = {2009}
}