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

High-coherence superconducting cavities are a promising platform for quantum information, offering excellent coherence and minimal intrinsic dephasing noise. However, cavity control relies on nonlinear Josephson devices used as ancillae or couplers, frequency fluctuations of which induce cavity dephasing, potentially limiting control fidelities and breaking the noise bias used for error-correction protocols. In this work, we propose a hardware-efficient protocol to protect the cavity from such inherited dephasing, using only a weak off-resonant microwave drive on the nonlinear device. As a concrete setting, we analyze a 3D superconducting cavity dispersively coupled to a flux-tunable transmon subject to \(1/f\) flux noise. Monte Carlo simulations with realistic parameters show that a weak drive can extend the cavity dephasing time by more than an order of magnitude without incurring detrimental effects from the additional drive.