Dynamics of Transmon Ionization

Superconducting circuit quantum electrodynamics (circuit QED) is one of the most promising platforms for quantum information processing. In typical circuit QED experiments, the quantum state of the qubit is measured by monitoring a readout resonator weakly and off-resonantly coupled to the qubit. As drive power is increased to achieve a higher-fidelity and faster measurement, unwanted transitions occur, which, for example, decrease the qubit’s energy relaxation time T₁. In this talk, focusing on the ubiquitously used transmon qubits, we address the phenomenon of escape into unconfined states [1,2], and unveil a mechanism for rate enhancement during measurement: by interactions between the low-lying states defining the qubit subspace and high-energy chaotic states [3]. This analysis provides important guidelines in the design of current experiments.

[1] L. Verney, R. Lescanne, M. H. Devoret, Z. Leghtas, and M. Mirrahimi, Phys. Rev. Applied 11, 024003 (2019)

[2] R. Shillito, A. Petrescu, J. Cohen, J. Beall, M. Hauru, M. Ganahl, A. G. M. Lewis, G. Vidal, and A. Blais, “Dynamics of transmon ionization” Phys. Rev. Applied 18, 034031 (2022).

[3] J. Cohen, A. Petrescu, R. Shillito, A. Blais, “Reminiscence of chaos in driven transmons” arXiv:2207.09361