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  Signatures of classical chaos in driven transmons


Alexandru Petrescu (Mines Paris)


Horaire/Time : le mardi 2 mai 2023 à 14:00


Lieu/Place : Visio-conférence Zoom hydride depuis Salle Rémy Lemaire K223, Institut Néel

Zoom link : https://univ-grenoble-alpes-fr.zoom.us/j/91808901596?pwd=UWZ2cml2N1VBOEZBenk0d3RJek9rdz09


Résumé/Abstract : Transmons are ubiquitously used in superconducting quantum information processing architectures. Strong drives are required to realize fast high-fidelity gates and measurements, including parametrically activated processes. We show that even off-resonant drives, in regimes routinely used in experiments, can cause strong modifications to the structure of the transmon spectrum rendering a large part of it chaotic. Chaotic states, often neglected through the hypothesis that the anharmonicity is weak, strongly impact the lifetime of the computational states. Chaos-assisted quantum phase slips greatly enhance band dispersions. In the presence of a readout resonator, the onset of chaos correlates with high transmon-resonator entanglement, and an average resonator response centered on the bare resonator frequency. We define a photon number threshold to characterize the appearance of chaos-induced quantum demolition effects during strong-drive operations, such as dispersive qubit readout. More generally, chaos-induced phenomena such as the ones studied here are expected to be present in all circuits based on low-impedance Josephson junctions.

Ref.: Joachim Cohen, Alexandru Petrescu, Ross Shillito, and Alexandre Blais, arXiv:2207.09361 ; Ross Shillito, Alexandru Petrescu, Joachim Cohen et al., Phys. Rev. Appl. 18, 034031 (2022)