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Quantum Nondemolition Dispersive Readout of a Superconducting Artificial Atom Using Large Photon Numbers

Gusenkova, Daria 1; Spiecker, Martin 1; Gebauer, Richard ORCID iD icon 2; Willsch, Madita; Willsch, Dennis; Valenti, Francesco 2; Karcher, Nick 2; Grünhaupt, Lukas 3; Takmakov, Ivan 1; Winkel, Patrick 1; Rieger, Dennis 3; Ustinov, Alexey V. 3; Roch, Nicolas; Wernsdorfer, Wolfgang 1; Michielsen, Kristel; Sander, Oliver 2; Pop, Ioan M. 1
1 Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT)
2 Institut für Prozessdatenverarbeitung und Elektronik (IPE), Karlsruher Institut für Technologie (KIT)
3 Karlsruher Institut für Technologie (KIT)


Reading out the state of superconducting artificial atoms typically relies on dispersive coupling to a readout resonator. For a given system noise temperature, increasing the circulating photon number $\overline{n}$ in the resonator enables a shorter measurement time and is therefore expected to reduce readout errors caused by spontaneous atom transitions. However, increasing $\overline{n}$ is generally observed to also monotonously increase these transition rates. Here we present a fluxonium artificial atom in which, despite the fact that the measured transition rates show nonmonotonous fluctuations within a factor of 6, for photon numbers up to $\overline{n}$≈200, the signal-to-noise ratio continuously improves with increasing $\overline{n}$. Even without the use of a parametric amplifier, at $\overline{n}$=74, we achieve fidelities of 99% and 93% for feedback-assisted ground and excited state preparations, respectively. At higher $\overline{n}$, leakage outside the qubit computational space can no longer be neglected and it limits the fidelity of quantum state preparation.

Preprint §
DOI: 10.5445/IR/1000134621
Veröffentlicht am 05.12.2022
DOI: 10.1103/PhysRevApplied.15.064030
Zitationen: 15
Zitationen: 20
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Prozessdatenverarbeitung und Elektronik (IPE)
Institut für QuantenMaterialien und Technologien (IQMT)
Physikalisches Institut (PHI)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2021
Sprache Englisch
Identifikator ISSN: 2331-7019
KITopen-ID: 1000134621
HGF-Programm 47.12.01 (POF IV, LK 01) Advanced Solid-State Qubits and Qubit Systems
Erschienen in Physical review applied
Verlag American Physical Society (APS)
Band 15
Heft 6
Seiten Art. Nr.: 064030
Vorab online veröffentlicht am 11.06.2021
Nachgewiesen in Scopus
Web of Science
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