Qubit decoherence and symmetry restoration through real-time instantons

Foster Thompson, Alex Kamenev

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


A parametrically driven quantum oscillator, stabilized by a nonlinear dissipation, exhibits a spontaneous breaking of the parity symmetry. It results in the quantum bistability, corresponding to a Bloch sphere of dark states. This makes such a driven-dissipative system an attractive candidate for a qubit. The parity symmetry breaking is exact both on the classical level and within the quantum mechanical perturbation theory. Here, we show that nonperturbative quantum effects lead to the symmetry restoration and result in an exponentially small but finite qubit decoherence rate. Technically, the symmetry restoration is due to real-time instanton trajectories of the Keldysh path integral, which represents the Lindbladian evolution of the driven-dissipative oscillator.

Original languageEnglish (US)
Article number023020
JournalPhysical Review Research
Issue number2
StatePublished - Jun 2022

Bibliographical note

Funding Information:
We are indebted to M. Dykman for numerous discussions. We also acknowledge helpful conversations with V. Albert and S. Girvin. This work was supported by the NSF Grant No. DMR-2037654.

Publisher Copyright:
© 2022 authors. Published by the American Physical Society.


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