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Implementation of a Transmon Qubit Using Superconducting Granular Aluminum

Winkel, Patrick 1; Borisov, Kiril 2; Grünhaupt, Lukas 1; Rieger, Dennis 1; Spiecker, Martin 1; Valenti, Francesco 3; Ustinov, Alexey V. 1; Wernsdorfer, Wolfgang 2; Pop, Ioan M. 2
1 Karlsruher Institut für Technologie (KIT)
2 Institut für Nanotechnologie (INT), Karlsruher Institut für Technologie (KIT)
3 Institut für Prozessdatenverarbeitung und Elektronik (IPE)


The high kinetic inductance offered by granular aluminum (grAl) has recently been employed for linear inductors in superconducting high-impedance qubits and kinetic inductance detectors. Because of its large critical current density compared to typical Josephson junctions, its resilience to external magnetic fields, and its low dissipation, grAl may also provide a robust source of nonlinearity for strongly driven quantum circuits, topological superconductivity, and hybrid systems. Having said that, can the grAl nonlinearity be sufficient to build a qubit? Here we show that a small grAl volume (10×200×500  nm$^{3}$) shunted by a thin film aluminum capacitor results in a microwave oscillator with anharmonicity α two orders of magnitude larger than its spectral linewidth Γ$_{01}$, effectively forming a transmon qubit. With increasing drive power, we observe several multiphoton transitions starting from the ground state, from which we extract α=2$_{π}$×4.48  MHz. Resonance fluorescence measurements of the |0⟩→|1⟩ transition yield an intrinsic qubit linewidth γ=2$_{π}$×10  kHz, corresponding to a lifetime of 16  μs, as confirmed by pulsed time-domain measurements. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000124175
Veröffentlicht am 02.10.2020
DOI: 10.1103/PhysRevX.10.031032
Web of Science
Zitationen: 21
Zitationen: 26
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Nanotechnologie (INT)
Institut für Prozessdatenverarbeitung und Elektronik (IPE)
Physikalisches Institut (PHI)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 2160-3308
KITopen-ID: 1000124175
HGF-Programm 43.21.02 (POF III, LK 01) Quantum Properties of Nanostructures
Erschienen in Physical review / X
Verlag American Physical Society (APS)
Band 10
Heft 3
Seiten Art.Nr. 031032
Vorab online veröffentlicht am 11.08.2020
Nachgewiesen in Dimensions
Web of Science
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