--- _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. Nature Physics. 2023;19:1630-1635. doi:10.1038/s41567-023-02161-w apa: Mukhopadhyay, S., Senior, J. L., Saez Mollejo, J., Puglia, D., Zemlicka, M., Fink, J. M., & Higginbotham, A. P. (2023). Superconductivity from a melted insulator in Josephson junction arrays. Nature Physics. Springer Nature. https://doi.org/10.1038/s41567-023-02161-w 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.” Nature Physics. Springer Nature, 2023. https://doi.org/10.1038/s41567-023-02161-w. ieee: S. Mukhopadhyay et al., “Superconductivity from a melted insulator in Josephson junction arrays,” Nature Physics, 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.” Nature Physics, vol. 19, Springer Nature, 2023, pp. 1630–35, doi:10.1038/s41567-023-02161-w. 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 license: https://creativecommons.org/licenses/by/4.0/ 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 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. Nature Materials. 2021;20(8):1106–1112. doi:10.1038/s41563-021-01022-2 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. Nature Materials. Springer Nature. https://doi.org/10.1038/s41563-021-01022-2 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.” Nature Materials. Springer Nature, 2021. https://doi.org/10.1038/s41563-021-01022-2. ieee: D. Jirovec et al., “A singlet triplet hole spin qubit in planar Ge,” Nature Materials, 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.” Nature Materials, vol. 20, no. 8, Springer Nature, 2021, pp. 1106–1112, doi:10.1038/s41563-021-01022-2. 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: 2024-03-27T23:30:26Z 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' ...