@article{19401,
  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.},
  author       = {Janik, Marian and Roux, Kevin Etienne Robert and Borja Espinosa, Carla N and Sagi, Oliver and Baghdadi, Abdulhamid and Adletzberger, Thomas and Calcaterra, Stefano and Botifoll, Marc and Garzón Manjón, Alba and Arbiol, Jordi and Chrastina, Daniel and Isella, Giovanni and Pop, Ioan M. and Katsaros, Georgios},
  issn         = {2041-1723},
  journal      = {Nature Communications},
  publisher    = {Springer Nature},
  title        = {{Strong charge-photon coupling in planar germanium enabled by granular aluminium superinductors}},
  doi          = {10.1038/s41467-025-57252-4},
  volume       = {16},
  year         = {2025},
}

@unpublished{18144,
  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 have integrated a granular
aluminium resonator, having a characteristic impedance exceeding the resistance
quantum, with a germanium double quantum dot and demonstrate strong
charge-photon coupling with a rate of $g_\text{c}/2\pi= (566 \pm 2)$ MHz. This
was achieved due to the realisation of a wireless ohmmeter, which allows
\emph{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 k$\Omega$ (1 nH per square)
is now possible. This broadly applicable method opens the path for novel qubits
and high-fidelity, long-distance two-qubit gates.},
  author       = {Janik, Marian and Roux, Kevin Etienne Robert and Borja Espinosa, Carla N and Sagi, Oliver and Baghdadi, Abdulhamid and Adletzberger, Thomas and Calcaterra, Stefano and Botifoll, Marc and Manjón, Alba Garzón and Arbiol, Jordi and Chrastina, Daniel and Isella, Giovanni and Pop, Ioan M. and Katsaros, Georgios},
  booktitle    = {arXiv},
  title        = {{Strong charge-photon coupling in planar germanium enabled by granular  aluminium superinductors}},
  doi          = {10.48550/arXiv.2407.03079},
  year         = {2024},
}