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Journal Articles Physical Review Applied Year : 2022

Dynamics of Transmon Ionization


Qubit measurement and control in circuit quantum electrodynamics (QED) rely on microwave drives, with higher drive amplitudes ideally leading to faster processes. However, degradation in qubit coherence time and readout fidelity has been observed even under moderate drive amplitudes corresponding to a few photons populating the measurement resonator. Here, we numerically explore the dynamics of a driven transmon-resonator system under strong and nearly resonant measurement drives and find clear signatures of transmon ionization where the qubit escapes out of its cosine potential. Using a semiclassical model, we interpret this ionization as resulting from resonances occurring at specific resonator-photon populations. We find that the photon populations at which these spurious transitions occur are strongly parameter dependent and that they can occur at low resonator-photon population, something that may explain the experimentally observed degradation in measurement fidelity.

Dates and versions

hal-03630643 , version 1 (05-04-2022)



Ross Shillito, Alexandru Petrescu, Joachim Cohen, Jackson Beall, Markus Hauru, et al.. Dynamics of Transmon Ionization. Physical Review Applied, 2022, 18 (3), pp.034031. ⟨10.1103/PhysRevApplied.18.034031⟩. ⟨hal-03630643⟩
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