---
_id: '14032'
abstract:
- lang: eng
  text: Arrays of Josephson junctions are governed by a competition between superconductivity
    and repulsive Coulomb interactions, and are expected to exhibit diverging low-temperature
    resistance when interactions exceed a critical level. Here we report a study of
    the transport and microwave response of Josephson arrays with interactions exceeding
    this level. Contrary to expectations, we observe that the array resistance drops
    dramatically as the temperature is decreased—reminiscent of superconducting behaviour—and
    then saturates at low temperature. Applying a magnetic field, we eventually observe
    a transition to a highly resistive regime. These observations can be understood
    within a theoretical picture that accounts for the effect of thermal fluctuations
    on the insulating phase. On the basis of the agreement between experiment and
    theory, we suggest that apparent superconductivity in our Josephson arrays arises
    from melting the zero-temperature insulator.
acknowledged_ssus:
- _id: M-Shop
- _id: NanoFab
acknowledgement: We thank D. Haviland, J. Pekola, C. Ciuti, A. Bubis and A. Shnirman
  for helpful feedback on the paper. This research was supported by the Scientific
  Service Units of IST Austria through resources provided by the MIBA Machine Shop
  and the Nanofabrication Facility. Work supported by the Austrian FWF grant P33692-N
  (S.M., J.S. and A.P.H.), the European Union’s Horizon 2020 Research and Innovation
  programme under the Marie Skłodowska-Curie Grant Agreement No. 754411 (J.S.) and
  a NOMIS foundation research grant (J.M.F. and A.P.H.).
article_processing_charge: Yes (in subscription journal)
article_type: original
author:
- first_name: Soham
  full_name: Mukhopadhyay, Soham
  id: FDE60288-A89D-11E9-947F-1AF6E5697425
  last_name: Mukhopadhyay
- first_name: Jorden L
  full_name: Senior, Jorden L
  id: 5479D234-2D30-11EA-89CC-40953DDC885E
  last_name: Senior
  orcid: 0000-0002-0672-9295
- first_name: Jaime
  full_name: Saez Mollejo, Jaime
  id: e0390f72-f6e0-11ea-865d-862393336714
  last_name: Saez Mollejo
- first_name: Denise
  full_name: Puglia, Denise
  id: 4D495994-AE37-11E9-AC72-31CAE5697425
  last_name: Puglia
  orcid: 0000-0003-1144-2763
- first_name: Martin
  full_name: Zemlicka, Martin
  id: 2DCF8DE6-F248-11E8-B48F-1D18A9856A87
  last_name: Zemlicka
- first_name: Johannes M
  full_name: Fink, Johannes M
  id: 4B591CBA-F248-11E8-B48F-1D18A9856A87
  last_name: Fink
  orcid: 0000-0001-8112-028X
- first_name: Andrew P
  full_name: Higginbotham, Andrew P
  id: 4AD6785A-F248-11E8-B48F-1D18A9856A87
  last_name: Higginbotham
  orcid: 0000-0003-2607-2363
citation:
  ama: Mukhopadhyay S, Senior JL, Saez Mollejo J, et al. Superconductivity from a
    melted insulator in Josephson junction arrays. <i>Nature Physics</i>. 2023;19:1630-1635.
    doi:<a href="https://doi.org/10.1038/s41567-023-02161-w">10.1038/s41567-023-02161-w</a>
  apa: Mukhopadhyay, S., Senior, J. L., Saez Mollejo, J., Puglia, D., Zemlicka, M.,
    Fink, J. M., &#38; Higginbotham, A. P. (2023). Superconductivity from a melted
    insulator in Josephson junction arrays. <i>Nature Physics</i>. Springer Nature.
    <a href="https://doi.org/10.1038/s41567-023-02161-w">https://doi.org/10.1038/s41567-023-02161-w</a>
  chicago: Mukhopadhyay, Soham, Jorden L Senior, Jaime Saez Mollejo, Denise Puglia,
    Martin Zemlicka, Johannes M Fink, and Andrew P Higginbotham. “Superconductivity
    from a Melted Insulator in Josephson Junction Arrays.” <i>Nature Physics</i>.
    Springer Nature, 2023. <a href="https://doi.org/10.1038/s41567-023-02161-w">https://doi.org/10.1038/s41567-023-02161-w</a>.
  ieee: S. Mukhopadhyay <i>et al.</i>, “Superconductivity from a melted insulator
    in Josephson junction arrays,” <i>Nature Physics</i>, vol. 19. Springer Nature,
    pp. 1630–1635, 2023.
  ista: Mukhopadhyay S, Senior JL, Saez Mollejo J, Puglia D, Zemlicka M, Fink JM,
    Higginbotham AP. 2023. Superconductivity from a melted insulator in Josephson
    junction arrays. Nature Physics. 19, 1630–1635.
  mla: Mukhopadhyay, Soham, et al. “Superconductivity from a Melted Insulator in Josephson
    Junction Arrays.” <i>Nature Physics</i>, vol. 19, Springer Nature, 2023, pp. 1630–35,
    doi:<a href="https://doi.org/10.1038/s41567-023-02161-w">10.1038/s41567-023-02161-w</a>.
  short: S. Mukhopadhyay, J.L. Senior, J. Saez Mollejo, D. Puglia, M. Zemlicka, J.M.
    Fink, A.P. Higginbotham, Nature Physics 19 (2023) 1630–1635.
date_created: 2023-08-11T07:41:17Z
date_published: 2023-11-01T00:00:00Z
date_updated: 2024-01-29T11:27:49Z
day: '01'
ddc:
- '530'
department:
- _id: GradSch
- _id: AnHi
- _id: JoFi
doi: 10.1038/s41567-023-02161-w
ec_funded: 1
external_id:
  isi:
  - '001054563800006'
file:
- access_level: open_access
  checksum: 1fc86d71bfbf836e221c1e925343adc5
  content_type: application/pdf
  creator: dernst
  date_created: 2024-01-29T11:25:38Z
  date_updated: 2024-01-29T11:25:38Z
  file_id: '14899'
  file_name: 2023_NaturePhysics_Mukhopadhyay.pdf
  file_size: 1977706
  relation: main_file
  success: 1
file_date_updated: 2024-01-29T11:25:38Z
has_accepted_license: '1'
intvolume: '        19'
isi: 1
keyword:
- General Physics and Astronomy
language:
- iso: eng
month: '11'
oa: 1
oa_version: Published Version
page: 1630-1635
project:
- _id: 0aa3608a-070f-11eb-9043-e9cd8a2bd931
  grant_number: P33692
  name: Cavity electromechanics across a quantum phase transition
- _id: 260C2330-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '754411'
  name: ISTplus - Postdoctoral Fellowships
- _id: eb9b30ac-77a9-11ec-83b8-871f581d53d2
  name: Protected states of quantum matter
- _id: bd5b4ec5-d553-11ed-ba76-a6eedb083344
  name: Protected states of quantum matter
publication: Nature Physics
publication_identifier:
  eissn:
  - 1745-2481
  issn:
  - 1745-2473
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
scopus_import: '1'
status: public
title: Superconductivity from a melted insulator in Josephson junction arrays
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 19
year: '2023'
...
---
_id: '8909'
abstract:
- lang: eng
  text: Spin qubits are considered to be among the most promising candidates for building
    a quantum processor. Group IV hole spin qubits have moved into the focus of interest
    due to the ease of operation and compatibility with Si technology. In addition,
    Ge offers the option for monolithic superconductor-semiconductor integration.
    Here we demonstrate a hole spin qubit operating at fields below 10 mT, the critical
    field of Al, by exploiting the large out-of-plane hole g-factors in planar Ge
    and by encoding the qubit into the singlet-triplet states of a double quantum
    dot. We observe electrically controlled X and Z-rotations with tunable frequencies
    exceeding 100 MHz and dephasing times of 1μs which we extend beyond 15μs with
    echo techniques. These results show that Ge hole singlet triplet qubits outperform
    their electronic Si and GaAs based counterparts in speed and coherence, respectively.
    In addition, they are on par with Ge single spin qubits, but can be operated at
    much lower fields underlining their potential for on chip integration with superconducting
    technologies.
acknowledged_ssus:
- _id: M-Shop
- _id: NanoFab
acknowledgement: This research was supported by the Scientific Service Units of Institute
  of Science and Technology (IST) Austria through resources provided by the Miba Machine
  Shop and the nanofabrication facility, and was made possible with the support of
  the NOMIS Foundation. This project has received funding from the European Union’s
  Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant
  agreements no. 844511 and no. 75441, and by the Austrian Science Fund FWF-P 30207
  project. A.B. acknowledges support from the European Union Horizon 2020 FET project
  microSPIRE, no. 766955. M. Botifoll and J.A. acknowledge funding from Generalitat
  de Catalunya 2017 SGR 327. The Catalan Institute of Nanoscience and Nanotechnology
  (ICN2) is supported by the Severo Ochoa programme from the Spanish Ministery of
  Economy (MINECO) (grant no. SEV-2017-0706) and is funded by the Catalonian Research
  Centre (CERCA) Programme, Generalitat de Catalunya. Part of the present work has
  been performed within the framework of the Universitat Autónoma de Barcelona Materials
  Science PhD programme. Part of the HAADF scanning transmission electron microscopy
  was conducted in the Laboratorio de Microscopias Avanzadas at Instituto de Nanociencia
  de Aragon, Universidad de Zaragoza. ICN2 acknowledge support from the Spanish Superior
  Council of Scientific Research (CSIC) Research Platform on Quantum Technologies
  PTI-001. M.B. acknowledges funding from the Catalan Agency for Management of University
  and Research Grants (AGAUR) Generalitat de Catalunya formation of investigators
  (FI) PhD grant.
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Daniel
  full_name: Jirovec, Daniel
  id: 4C473F58-F248-11E8-B48F-1D18A9856A87
  last_name: Jirovec
  orcid: 0000-0002-7197-4801
- first_name: Andrea C
  full_name: Hofmann, Andrea C
  id: 340F461A-F248-11E8-B48F-1D18A9856A87
  last_name: Hofmann
- first_name: Andrea
  full_name: Ballabio, Andrea
  last_name: Ballabio
- first_name: Philipp M.
  full_name: Mutter, Philipp M.
  last_name: Mutter
- first_name: Giulio
  full_name: Tavani, Giulio
  last_name: Tavani
- first_name: Marc
  full_name: Botifoll, Marc
  last_name: Botifoll
- first_name: Alessandro
  full_name: Crippa, Alessandro
  id: 1F2B21A2-F6E7-11E9-9B82-F7DBE5697425
  last_name: Crippa
  orcid: 0000-0002-2968-611X
- first_name: Josip
  full_name: Kukucka, Josip
  id: 3F5D8856-F248-11E8-B48F-1D18A9856A87
  last_name: Kukucka
- first_name: Oliver
  full_name: Sagi, Oliver
  id: 71616374-A8E9-11E9-A7CA-09ECE5697425
  last_name: Sagi
- first_name: Frederico
  full_name: Martins, Frederico
  id: 38F80F9A-1CB8-11EA-BC76-B49B3DDC885E
  last_name: Martins
  orcid: 0000-0003-2668-2401
- first_name: Jaime
  full_name: Saez Mollejo, Jaime
  id: e0390f72-f6e0-11ea-865d-862393336714
  last_name: Saez Mollejo
- first_name: Ivan
  full_name: Prieto Gonzalez, Ivan
  id: 2A307FE2-F248-11E8-B48F-1D18A9856A87
  last_name: Prieto Gonzalez
  orcid: 0000-0002-7370-5357
- first_name: Maksim
  full_name: Borovkov, Maksim
  id: 2ac7a0a2-3562-11eb-9256-fbd18ea55087
  last_name: Borovkov
- first_name: Jordi
  full_name: Arbiol, Jordi
  last_name: Arbiol
- first_name: Daniel
  full_name: Chrastina, Daniel
  last_name: Chrastina
- first_name: Giovanni
  full_name: Isella, Giovanni
  last_name: Isella
- first_name: Georgios
  full_name: Katsaros, Georgios
  id: 38DB5788-F248-11E8-B48F-1D18A9856A87
  last_name: Katsaros
  orcid: 0000-0001-8342-202X
citation:
  ama: Jirovec D, Hofmann AC, Ballabio A, et al. A singlet triplet hole spin qubit
    in planar Ge. <i>Nature Materials</i>. 2021;20(8):1106–1112. doi:<a href="https://doi.org/10.1038/s41563-021-01022-2">10.1038/s41563-021-01022-2</a>
  apa: Jirovec, D., Hofmann, A. C., Ballabio, A., Mutter, P. M., Tavani, G., Botifoll,
    M., … Katsaros, G. (2021). A singlet triplet hole spin qubit in planar Ge. <i>Nature
    Materials</i>. Springer Nature. <a href="https://doi.org/10.1038/s41563-021-01022-2">https://doi.org/10.1038/s41563-021-01022-2</a>
  chicago: Jirovec, Daniel, Andrea C Hofmann, Andrea Ballabio, Philipp M. Mutter,
    Giulio Tavani, Marc Botifoll, Alessandro Crippa, et al. “A Singlet Triplet Hole
    Spin Qubit in Planar Ge.” <i>Nature Materials</i>. Springer Nature, 2021. <a href="https://doi.org/10.1038/s41563-021-01022-2">https://doi.org/10.1038/s41563-021-01022-2</a>.
  ieee: D. Jirovec <i>et al.</i>, “A singlet triplet hole spin qubit in planar Ge,”
    <i>Nature Materials</i>, vol. 20, no. 8. Springer Nature, pp. 1106–1112, 2021.
  ista: Jirovec D, Hofmann AC, Ballabio A, Mutter PM, Tavani G, Botifoll M, Crippa
    A, Kukucka J, Sagi O, Martins F, Saez Mollejo J, Prieto Gonzalez I, Borovkov M,
    Arbiol J, Chrastina D, Isella G, Katsaros G. 2021. A singlet triplet hole spin
    qubit in planar Ge. Nature Materials. 20(8), 1106–1112.
  mla: Jirovec, Daniel, et al. “A Singlet Triplet Hole Spin Qubit in Planar Ge.” <i>Nature
    Materials</i>, vol. 20, no. 8, Springer Nature, 2021, pp. 1106–1112, doi:<a href="https://doi.org/10.1038/s41563-021-01022-2">10.1038/s41563-021-01022-2</a>.
  short: D. Jirovec, A.C. Hofmann, A. Ballabio, P.M. Mutter, G. Tavani, M. Botifoll,
    A. Crippa, J. Kukucka, O. Sagi, F. Martins, J. Saez Mollejo, I. Prieto Gonzalez,
    M. Borovkov, J. Arbiol, D. Chrastina, G. Isella, G. Katsaros, Nature Materials
    20 (2021) 1106–1112.
date_created: 2020-12-02T10:50:47Z
date_published: 2021-08-01T00:00:00Z
date_updated: 2024-03-25T23:30:14Z
day: '01'
department:
- _id: GeKa
- _id: NanoFab
- _id: GradSch
doi: 10.1038/s41563-021-01022-2
ec_funded: 1
external_id:
  arxiv:
  - '2011.13755'
  isi:
  - '000657596400001'
intvolume: '        20'
isi: 1
issue: '8'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/2011.13755
month: '08'
oa: 1
oa_version: Preprint
page: 1106–1112
project:
- _id: 26A151DA-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '844511'
  name: Majorana bound states in Ge/SiGe heterostructures
- _id: 260C2330-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '754411'
  name: ISTplus - Postdoctoral Fellowships
- _id: 2641CE5E-B435-11E9-9278-68D0E5697425
  call_identifier: FWF
  grant_number: P30207
  name: Hole spin orbit qubits in Ge quantum wells
- _id: 262116AA-B435-11E9-9278-68D0E5697425
  name: Hybrid Semiconductor - Superconductor Quantum Devices
publication: Nature Materials
publication_identifier:
  eissn:
  - 1476-4660
  issn:
  - 1476-1122
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
related_material:
  link:
  - description: News on IST Homepage
    relation: press_release
    url: https://ist.ac.at/en/news/quantum-computing-with-holes/
  record:
  - id: '9323'
    relation: research_data
    status: public
  - id: '10058'
    relation: dissertation_contains
    status: public
scopus_import: '1'
status: public
title: A singlet triplet hole spin qubit in planar Ge
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 20
year: '2021'
...