Strong charge-photon coupling in planar germanium enabled by granular aluminium superinductors
Janík, Marián (Institute of Science and Technology Austria)
Roux, Kevin (Institute of Science and Technology Austria)
Borja-Espinosa, Carla (Institute of Science and Technology Austria)
Sagi, Oliver (Institute of Science and Technology Austria)
Baghdadi, Abdulhamid (Institute of Science and Technology Austria)
Adletzberger, Thomas (Institute of Science and Technology Austria)
Calcaterra, Stefano (Politecnico di Milano. Physics Department)
Botifoll, Marc (Institut Català de Nanociència i Nanotecnologia)
Garzón-Manjón, Alba (Institut Català de Nanociència i Nanotecnologia)
Arbiol i Cobos, Jordi (Institut Català de Nanociència i Nanotecnologia)
Chrastina, Daniel (Politecnico di Milano. Physics Department)
Isella, Giovanni (Politecnico di Milano. Physics Department)
Pop, Ioan (Stuttgart University)
Katsaros, Georgios (Institute of Science and Technology Austria)

Date:	2025
Abstract:	High kinetic inductance superconductors are gaining increasing interest for the realisation of qubits, amplifiers and detectors. Moreover, thanks to their high impedance, quantum buses made of such materials enable large zero-point fluctuations of the voltage, boosting the coupling rates to spin and charge qubits. However, fully exploiting the potential of disordered or granular superconductors is challenging, as their inductance and, therefore, impedance at high values are difficult to control. Here, we report a reproducible fabrication of granular aluminium resonators by developing a wireless ohmmeter, which allows in situ measurements during film deposition and, therefore, control of the kinetic inductance of granular aluminium films. Reproducible fabrication of circuits with impedances (inductances) exceeding 13 kΩ (1 nH per square) is now possible. By integrating a 7. 9 kΩ resonator with a germanium double quantum dot, we demonstrate strong charge-photon coupling with a rate of gc/2π = 566 ± 2 MHz. This broadly applicable method opens the path for novel qubits and high-fidelity, long-distance two-qubit gates.
Grants:	European Commission 101069515 European Commission 101034413 Agència de Gestió d'Ajuts Universitaris i de Recerca 2021/SGR-00457 Agència de Gestió d'Ajuts Universitaris i de Recerca 2020/FI-00103 Ministerio de Ciencia e Innovación CEX2021-001214-S Ministerio de Ciencia e Innovación RYC2021-033479-I
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Quantum information ; Superconducting devices
Published in:	Nature communications, Vol. 16 (March 2025) , art. 2103, ISSN 2041-1723

DOI: 10.1038/s41467-025-57252-4
PMID: 40025007

9 p, 5.9 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Articles > Research articles
Articles > Published articles