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Spin bath-mediated decoherence in superconductors

Nikolay Prokof'ev·Philip Stamp
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Abstract

We consider a SQUID tunneling between 2 nearly degenerate flux states. Decoherence caused by paramagnetic and nuclear spins in the low-$T$ limit is shown to be much stronger than that from electronic excitations. The decoherence time $τ_ϕ$ is determined by the linewidth $E_o$ of spin bath states, which can be reduced by a correct choice of ring geometry and isotopic purification. $E_o$ can be measured in either field sweep or microwave absorption experiments, allowing both a test of the theory and design control.

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Nikolay Prokof'ev, Philip Stamp. 2000-06-04. Spin bath-mediated decoherence in superconductors. https://arxiv.org/abs/cond-mat/0006054

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