Quasiparticle-induced decoherence of a driven superconducting qubit
Phys. Rev. Applied 26, 014091 – Published 29 July, 2026
DOI: https://doi.org/10.1103/3q5z-tk7c
Abstract
We develop a theory for two quasiparticle-induced decoherence mechanisms of a driven superconducting qubit. In the first mechanism, an existing quasiparticle (QP) tunnels across the qubit’s Josephson junction while simultaneously absorbing a qubit excitation and one (or several) photons from the drive. In the second mechanism, a qubit transition occurs during the nonlinear absorption process converting multiple drive quanta into a pair of new QPs. Both mechanisms can remain significant in gap-engineered qubits whose coherence is insensitive to QPs without the drive. Our theory establishes a fundamental limitation on fidelity of the microwave qubit operations—such as readout and gates—stemming from QPs.
