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Observation of Josephson harmonics in tunnel junctions

Willsch, Dennis; Rieger, Dennis ORCID iD icon 1,2; Winkel, Patrick 1,2; Willsch, Madita; Dickel, Christian; Krause, Jonas; Ando, Yoichi; Lescanne, Raphaël; Leghtas, Zaki; Bronn, Nicholas T.; Deb, Pratiti; Lanes, Olivia; Minev, Zlatko K.; Dennig, Benedikt 1,2; Geisert, Simon 2; Günzler, Simon ORCID iD icon 2; Ihssen, Sören 2; Paluch, Patrick 1,2; Reisinger, Thomas 2; ... mehr

Abstract:

Approaches to developing large-scale superconducting quantum
processors must cope with the numerous microscopic degrees of freedom
that are ubiquitous in solid-state devices. State-of-the-art superconducting
qubits employ aluminium oxide (AlOx) tunnel Josephson junctions as
the sources of nonlinearity necessary to perform quantum operations.
Analyses of these junctions typically assume an idealized, purely sinusoidal
current–phase relation. However, this relation is expected to hold only in the
limit of vanishingly low-transparency channels in the AlOx barrier. Here we
show that the standard current–phase relation fails to accurately describe
the energy spectra of transmon artificial atoms across various samples
and laboratories. Instead, a mesoscopic model of tunnelling through
an inhomogeneous AlOx barrier predicts percent-level contributions
from higher Josephson harmonics. By including these in the transmon
Hamiltonian, we obtain orders of magnitude better agreement between
the computed and measured energy spectra. The presence and impact of
Josephson harmonics has important implications for developing AlOx-based
... mehr

Zugehörige Institution(en) am KIT Institut für QuantenMaterialien und Technologien (IQMT)
Physikalisches Institut (PHI)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 05.2024
Sprache Englisch
Identifikator ISSN: 1745-2473, 1745-2481
KITopen-ID: 1000168885
HGF-Programm 47.12.01 (POF IV, LK 01) Advanced Solid-State Qubits and Qubit Systems
Erschienen in Nature Physics
Verlag Nature Research
Band 20
Heft 5
Seiten 815–821
Vorab online veröffentlicht am 14.02.2024
Nachgewiesen in Web of Science
OpenAlex
Dimensions
Scopus
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Verlagsausgabe §
DOI: 10.5445/IR/1000168885
Veröffentlicht am 05.03.2024
Originalveröffentlichung
DOI: 10.1038/s41567-024-02400-8
Scopus
Zitationen: 22
Web of Science
Zitationen: 20
Dimensions
Zitationen: 32
Seitenaufrufe: 195
seit 05.03.2024
Downloads: 83
seit 06.03.2024
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