Spin bath-mediated decoherence in superconductors
arXiv:cond-mat/0006054
Abstract
We consider a SQUID tunneling between 2 nearly degenerate flux states. Decoherence caused by paramagnetic and nuclear spins in the low- limit is shown to be much stronger than that from electronic excitations. The decoherence time is determined by the linewidth of spin bath states, which can be reduced by a correct choice of ring geometry and isotopic purification. can be measured in either field sweep or microwave absorption experiments, allowing both a test of the theory and design control.
5 pages, LaTex, 3 figures, submitted to PRL in May, 2000