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arXiv · 2608.04494

Dynamically suppressing cavity dephasing induced by frequency fluctuations of a coupled nonlinear mode

Yunwei Lu·Xinyuan You·Ziwen Huang·Sébastien Léger·Jens Koch·Yao Lu
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Abstract

High-coherence superconducting cavities offer a promising platform for quantum information, with long coherence times and negligible intrinsic dephasing. However, cavity control generally relies on nonlinear Josephson elements whose frequency fluctuations are inherited by the cavity as dephasing, potentially limiting control fidelities and eroding the noise bias used in error-correction protocols. Here, we introduce Stark-Assisted Flux-noise Evasion (SAFE), a hardware-efficient protocol that protects the cavity from inherited dephasing using only a weak off-resonant microwave drive applied to the nonlinear element. As a concrete setup, we analyze a 3D superconducting cavity dispersively coupled to a flux-tunable transmon (FTT) subject to $1/f$ flux noise. Analytical predictions are confirmed by Monte Carlo simulations with realistic parameters, which show that SAFE can extend the cavity dephasing time by more than an order of magnitude while keeping residual drive-induced decoherence subdominant.

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Yunwei Lu, Xinyuan You, Ziwen Huang, Sébastien Léger, Jens Koch, Yao Lu. 2026-09-14. Dynamically suppressing cavity dephasing induced by frequency fluctuations of a coupled nonlinear mode. https://arxiv.org/abs/2608.04494

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