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arXiv · 1410.8715

Qubit dephasing due to Quasiparticle Tunneling

Sebastian Zanker·Michael Marthaler
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Abstract

We study dephasing of a superconducting qubit due to quasiparticle tunneling through a Josephson junction. While qubit decay due to tunneling processes is well understood within a golden rule approximation, pure dephasing due to BCS quasiparticles gives rise to a divergent golden rule rate. We calculate qubit dephasing due to quasiparticle tunneling beyond lowest order approximation in coupling between qubit and quasiparticles. Summing up a certain class of diagrams we show that qubit dephasing due to purely longitudinal coupling to quasiparticles leads to a dephasing $\sim \exp(-x(t))$ where $x(t)$ is not linear in time on short time scales while it tends towards a selfconsistent calculated dephasing rate for longer times.

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Sebastian Zanker, Michael Marthaler. 2014-11-06. Qubit dephasing due to Quasiparticle Tunneling. https://doi.org/10.1103/physrevb.91.174504

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