[{"publisher":"Springer Nature","publication":"Nature Communications","OA_place":"publisher","has_accepted_license":"1","status":"public","arxiv":1,"corr_author":"1","month":"04","intvolume":"        16","publication_identifier":{"eissn":["2041-1723"]},"ddc":["530"],"article_number":"3862","external_id":{"pmid":["40274808"],"arxiv":["2408.03224"],"isi":["001475587400022"]},"acknowledgement":"We thank A. Crippa for helpful discussions. This research was supported by the Scientific Service Units of ISTA through resources provided by the MIBA Machine Shop and the Nanofabrication facility. This research and related results were made possible with the support of the NOMIS Foundation, the HORIZON-RIA 101069515 project and the FWF Projects with DOI:10.55776/F86 and DOI:10.55776/I5060. M.R.-R. acknowledges support from the Netherlands Organization of Scientific Research (NWO) under Veni grant VI.Veni.212.223. The\r\nResearch of S.B. and M.R.-R. was sponsored in part by the Army Research Office and was accomplished under Award Number: W911NF-23-1-0110. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Office or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein.","author":[{"id":"e0390f72-f6e0-11ea-865d-862393336714","last_name":"Saez Mollejo","first_name":"Jaime","full_name":"Saez Mollejo, Jaime"},{"last_name":"Jirovec","full_name":"Jirovec, Daniel","first_name":"Daniel","orcid":"0000-0002-7197-4801","id":"4C473F58-F248-11E8-B48F-1D18A9856A87"},{"id":"fe39122d-06bb-11ec-a33b-9e22b40e40a5","last_name":"Schell","full_name":"Schell, Yona A","first_name":"Yona A"},{"id":"3F5D8856-F248-11E8-B48F-1D18A9856A87","first_name":"Josip","full_name":"Kukucka, Josip","last_name":"Kukucka"},{"last_name":"Calcaterra","full_name":"Calcaterra, Stefano","first_name":"Stefano"},{"first_name":"Daniel","full_name":"Chrastina, Daniel","last_name":"Chrastina"},{"last_name":"Isella","full_name":"Isella, Giovanni","first_name":"Giovanni"},{"last_name":"Rimbach-Russ","first_name":"Maximilian","full_name":"Rimbach-Russ, Maximilian"},{"last_name":"Bosco","first_name":"Stefano","full_name":"Bosco, Stefano"},{"last_name":"Katsaros","first_name":"Georgios","full_name":"Katsaros, Georgios","orcid":"0000-0001-8342-202X","id":"38DB5788-F248-11E8-B48F-1D18A9856A87"}],"article_processing_charge":"Yes","title":"Exchange anisotropies in microwave-driven singlet-triplet qubits","year":"2025","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","volume":16,"pmid":1,"date_published":"2025-04-24T00:00:00Z","oa_version":"Published Version","abstract":[{"text":"Hole spin qubits are rapidly emerging as the workhorse of semiconducting quantum processors because of their large spin-orbit interaction, enabling fast all-electric operations at low power. However, spin-orbit interaction also causes non-uniformities in devices, resulting in locally varying qubit energies and site-dependent anisotropies. While these anisotropies can be used to drive single-spins, if not properly harnessed, they can hinder the path toward large-scale quantum processors. Here, we report on microwave-driven singlet-triplet qubits in planar germanium and use them to investigate the anisotropy of two spins in a double quantum dot. We show two distinct operating regimes depending on the magnetic field direction. For in-plane fields, the two spins are largely anisotropic, and electrically tunable, which enables to measure all the available transitions; coherence times exceeding 3 $\\mu$s are extracted. For out-of-plane fields, they have an isotropic response but preserve the substantial energy difference required to address the singlet-triplet qubit. Even in this field direction, where the qubit lifetime\r\nis strongly affected by nuclear spins, we find 400 ns coherence times. Our work adds a valuable tool to investigate and harness the anisotropy of spin qubits and can be implemented in any large-scale NxN device, facilitating the path towards scalable quantum processors.","lang":"eng"}],"oa":1,"language":[{"iso":"eng"}],"file_date_updated":"2025-05-05T07:08:23Z","OA_type":"gold","scopus_import":"1","_id":"19424","related_material":{"link":[{"relation":"research_data","description":"News on ISTA website","url":"https://ista.ac.at/en/news/the-shadow-of-an-electron/"}],"record":[{"status":"public","id":"19409","relation":"research_data"},{"relation":"dissertation_contains","id":"19836","status":"public"}]},"quality_controlled":"1","citation":{"ista":"Saez Mollejo J, Jirovec D, Schell YA, Kukucka J, Calcaterra S, Chrastina D, Isella G, Rimbach-Russ M, Bosco S, Katsaros G. 2025. Exchange anisotropies in microwave-driven singlet-triplet qubits. Nature Communications. 16, 3862.","ama":"Saez Mollejo J, Jirovec D, Schell YA, et al. Exchange anisotropies in microwave-driven singlet-triplet qubits. <i>Nature Communications</i>. 2025;16. doi:<a href=\"https://doi.org/10.1038/s41467-025-58969-y\">10.1038/s41467-025-58969-y</a>","apa":"Saez Mollejo, J., Jirovec, D., Schell, Y. A., Kukucka, J., Calcaterra, S., Chrastina, D., … Katsaros, G. (2025). Exchange anisotropies in microwave-driven singlet-triplet qubits. <i>Nature Communications</i>. Springer Nature. <a href=\"https://doi.org/10.1038/s41467-025-58969-y\">https://doi.org/10.1038/s41467-025-58969-y</a>","ieee":"J. Saez Mollejo <i>et al.</i>, “Exchange anisotropies in microwave-driven singlet-triplet qubits,” <i>Nature Communications</i>, vol. 16. Springer Nature, 2025.","mla":"Saez Mollejo, Jaime, et al. “Exchange Anisotropies in Microwave-Driven Singlet-Triplet Qubits.” <i>Nature Communications</i>, vol. 16, 3862, Springer Nature, 2025, doi:<a href=\"https://doi.org/10.1038/s41467-025-58969-y\">10.1038/s41467-025-58969-y</a>.","short":"J. Saez Mollejo, D. Jirovec, Y.A. Schell, J. Kukucka, S. Calcaterra, D. Chrastina, G. Isella, M. Rimbach-Russ, S. Bosco, G. Katsaros, Nature Communications 16 (2025).","chicago":"Saez Mollejo, Jaime, Daniel Jirovec, Yona A Schell, Josip Kukucka, Stefano Calcaterra, Daniel Chrastina, Giovanni Isella, Maximilian Rimbach-Russ, Stefano Bosco, and Georgios Katsaros. “Exchange Anisotropies in Microwave-Driven Singlet-Triplet Qubits.” <i>Nature Communications</i>. Springer Nature, 2025. <a href=\"https://doi.org/10.1038/s41467-025-58969-y\">https://doi.org/10.1038/s41467-025-58969-y</a>."},"DOAJ_listed":"1","date_updated":"2026-07-08T22:30:43Z","acknowledged_ssus":[{"_id":"M-Shop"},{"_id":"NanoFab"}],"APC_amount":"7068 EUR","doi":"10.1038/s41467-025-58969-y","department":[{"_id":"GeKa"}],"file":[{"date_created":"2025-05-05T07:08:23Z","file_size":1548756,"creator":"dernst","relation":"main_file","file_id":"19645","date_updated":"2025-05-05T07:08:23Z","file_name":"2025_NatureComm_SaezMollejo.pdf","checksum":"13fe84cddc9d4e47213bf17acdac70d7","access_level":"open_access","success":1,"content_type":"application/pdf"}],"publication_status":"published","date_created":"2025-03-19T13:28:12Z","type":"journal_article","tmp":{"short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png"},"isi":1,"day":"24","project":[{"_id":"34c0acea-11ca-11ed-8bc3-8775e10fd452","grant_number":"101069515","name":"Integrated Germanium Quantum Technology"},{"_id":"34a66131-11ca-11ed-8bc3-a31681c6b03e","grant_number":"F8606","name":"Center for Correlated Quantum Materials and Solid State Quantum Systems: Conventional  and unconventional topological superconductors"},{"_id":"c0977eea-5a5b-11eb-8a69-a862db0cf4d1","grant_number":"I05060","name":"High impedance circuit quantum electrodynamics with hole spins"},{"_id":"262116AA-B435-11E9-9278-68D0E5697425","name":"Hybrid Semiconductor - Superconductor Quantum Devices"},{"call_identifier":"FWF","_id":"3AC91DDA-15DF-11EA-824D-93A3E7B544D1","name":"FWF Open Access Fund"}],"article_type":"original"},{"ddc":["530"],"acknowledgement":"This research was supported by the Scientific Service Units of ISTA through resources provided by the MIBA Machine Shop and the Nanofabrication facility. ","author":[{"id":"71616374-A8E9-11E9-A7CA-09ECE5697425","last_name":"Sagi","full_name":"Sagi, Oliver","first_name":"Oliver"}],"article_processing_charge":"No","title":"A gate-tunable transmon in planar Ge","year":"2024","user_id":"68b8ca59-c5b3-11ee-8790-cd641c68093d","date_published":"2024-07-04T00:00:00Z","oa_version":"Published Version","publisher":"Institute of Science and Technology Austria","has_accepted_license":"1","status":"public","corr_author":"1","month":"07","doi":"10.15479/AT:ISTA:17196","department":[{"_id":"GradSch"},{"_id":"GeKa"},{"_id":"JoFi"}],"file":[{"date_created":"2024-07-04T10:01:51Z","file_size":1960182,"creator":"osagi","file_id":"17197","relation":"main_file","date_updated":"2024-07-04T10:01:51Z","file_name":"GeGatemon_DataAnalysis.ipynb","checksum":"a9f640a0b72a92171353f3ea14406f0b","access_level":"open_access","success":1,"content_type":"application/octet-stream"},{"file_id":"17198","relation":"main_file","date_created":"2024-07-04T10:01:50Z","file_size":34194,"creator":"osagi","content_type":"application/vnd.openxmlformats-officedocument.presentationml.presentation","date_updated":"2024-07-04T10:01:50Z","file_name":"OlSa_Readme.pptx","checksum":"f0feec931233e8e845ade56165c1588f","access_level":"open_access","success":1},{"file_id":"17199","relation":"main_file","creator":"osagi","file_size":72939292,"date_created":"2024-07-04T10:11:16Z","content_type":"application/x-zip-compressed","success":1,"access_level":"open_access","checksum":"92bb11e3a508d736d01ff0738a1172c7","file_name":"Al_Transmon.zip","date_updated":"2024-07-04T10:11:16Z"},{"file_size":465618029,"date_created":"2024-07-04T10:11:40Z","creator":"osagi","relation":"main_file","file_id":"17200","file_name":"Gatemon_RT_5nm_1.zip","date_updated":"2024-07-04T10:11:40Z","success":1,"access_level":"open_access","checksum":"871e96fe0ecc97581196e883045cd516","content_type":"application/x-zip-compressed"},{"file_id":"17201","relation":"main_file","creator":"osagi","date_created":"2024-07-04T10:11:35Z","file_size":281503513,"content_type":"application/x-zip-compressed","checksum":"a3e141af90f0104b7269c8a72370848a","access_level":"open_access","success":1,"date_updated":"2024-07-04T10:11:35Z","file_name":"Gatemon_RT_5nm_2.zip"}],"date_created":"2024-07-04T10:14:34Z","tmp":{"short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png"},"type":"research_data","day":"04","project":[{"grant_number":"I05060","name":"High impedance circuit quantum electrodynamics with hole spins","_id":"c0977eea-5a5b-11eb-8a69-a862db0cf4d1"},{"name":"Hybrid Semiconductor - Superconductor Quantum Devices","_id":"262116AA-B435-11E9-9278-68D0E5697425"},{"_id":"bd8bd29e-d553-11ed-ba76-f0070d4b237a","grant_number":"P36507","name":"Merging spin and superconducting qubits in planar Ge"}],"contributor":[{"last_name":"Crippa","first_name":"Alessandro","orcid":"0000-0002-2968-611X","contributor_type":"project_member","id":"1F2B21A2-F6E7-11E9-9B82-F7DBE5697425"},{"contributor_type":"project_member","id":"C0BB2FAC-D767-11E9-B658-BC13E6697425","last_name":"Valentini","first_name":"Marco"},{"last_name":"Janik","first_name":"Marian","contributor_type":"project_member","id":"396A1950-F248-11E8-B48F-1D18A9856A87"},{"last_name":"Baghumyan","first_name":"Levon","contributor_type":"project_member","id":"7aa1f788-b527-11ee-aa9e-e6111a79e0c7"},{"first_name":"Giorgio","last_name":"Fabris","id":"298cf6f3-1ff6-11ee-9fa6-d94cfa0b3352","contributor_type":"project_member"},{"last_name":"Kapoor","first_name":"Lucky","contributor_type":"project_member","id":"84b9700b-15b2-11ec-abd3-831089e67615"},{"id":"2AED110C-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-6937-5773","contributor_type":"project_member","first_name":"Farid","last_name":"Hassani"},{"id":"4B591CBA-F248-11E8-B48F-1D18A9856A87","contributor_type":"project_member","orcid":"0000-0001-8112-028X","first_name":"Johannes M","last_name":"Fink"},{"contributor_type":"project_member","first_name":"Stefano","last_name":"Calcaterra"},{"last_name":"Chrastina","first_name":"Daniel","contributor_type":"project_member"},{"last_name":"Isella","first_name":"Giovanni","contributor_type":"project_member"},{"id":"38DB5788-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-8342-202X","contributor_type":"supervisor","first_name":"Georgios","last_name":"Katsaros"}],"abstract":[{"lang":"eng","text":"This .zip File contains the data for the figures presented in the main text and supplementary material of \"A gate tunable transmon qubit in planar Ge\" by O.Sagi et al. The measurements were done using Qcodes. The description of the files and the instructions on opening the data can be found in the Readme. An additional Jupyter Notebook is attached that walks through the data analysis."}],"file_date_updated":"2024-07-04T10:11:40Z","oa":1,"_id":"17196","related_material":{"record":[{"id":"17202","relation":"used_in_publication","status":"public"}]},"date_updated":"2026-04-16T12:20:39Z","citation":{"short":"O. Sagi, (2024).","chicago":"Sagi, Oliver. “A Gate-Tunable Transmon in Planar Ge.” Institute of Science and Technology Austria, 2024. <a href=\"https://doi.org/10.15479/AT:ISTA:17196\">https://doi.org/10.15479/AT:ISTA:17196</a>.","ieee":"O. Sagi, “A gate-tunable transmon in planar Ge.” Institute of Science and Technology Austria, 2024.","mla":"Sagi, Oliver. <i>A Gate-Tunable Transmon in Planar Ge</i>. Institute of Science and Technology Austria, 2024, doi:<a href=\"https://doi.org/10.15479/AT:ISTA:17196\">10.15479/AT:ISTA:17196</a>.","ama":"Sagi O. A gate-tunable transmon in planar Ge. 2024. doi:<a href=\"https://doi.org/10.15479/AT:ISTA:17196\">10.15479/AT:ISTA:17196</a>","apa":"Sagi, O. (2024). A gate-tunable transmon in planar Ge. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/AT:ISTA:17196\">https://doi.org/10.15479/AT:ISTA:17196</a>","ista":"Sagi O. 2024. A gate-tunable transmon in planar Ge, Institute of Science and Technology Austria, <a href=\"https://doi.org/10.15479/AT:ISTA:17196\">10.15479/AT:ISTA:17196</a>."},"acknowledged_ssus":[{"_id":"NanoFab"},{"_id":"M-Shop"}]},{"doi":"10.1038/s41467-024-50763-6","department":[{"_id":"GeKa"},{"_id":"JoFi"},{"_id":"GradSch"}],"file":[{"content_type":"application/pdf","date_updated":"2024-08-05T08:38:01Z","file_name":"2024_NatureComm_Sagi.pdf","checksum":"ddf5361dcb6c543e2cea818501c09910","success":1,"access_level":"open_access","file_id":"17388","relation":"main_file","date_created":"2024-08-05T08:38:01Z","file_size":1928001,"creator":"dernst"}],"APC_amount":"6828 EUR","publication_status":"published","date_created":"2024-07-04T11:40:45Z","type":"journal_article","tmp":{"short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png"},"project":[{"_id":"bd8bd29e-d553-11ed-ba76-f0070d4b237a","grant_number":"P36507","name":"Merging spin and superconducting qubits in planar Ge"},{"_id":"c0977eea-5a5b-11eb-8a69-a862db0cf4d1","grant_number":"I05060","name":"High impedance circuit quantum electrodynamics with hole spins"},{"name":"Hybrid Semiconductor - Superconductor Quantum Devices","_id":"262116AA-B435-11E9-9278-68D0E5697425"},{"call_identifier":"FWF","_id":"3AC91DDA-15DF-11EA-824D-93A3E7B544D1","name":"FWF Open Access Fund"}],"day":"30","isi":1,"article_type":"original","abstract":[{"lang":"eng","text":"Gate-tunable transmons (gatemons) employing semiconductor Josephson junctions have recently emerged as building blocks for hybrid quantum circuits. In this study, we present a gatemon fabricated in planar Germanium. We induce superconductivity in a two-dimensional hole gas by evaporating aluminum atop a thin spacer, which separates the superconductor from the Ge quantum well. The Josephson junction is then integrated into an Xmon circuit and capacitively coupled to a transmission line resonator. We showcase the qubit tunability in a broad frequency range with resonator and two-tone spectroscopy. Time-domain characterizations reveal energy relaxation and coherence times up to 75 ns. Our results, combined with the recent advances in the spin qubit field, pave the way towards novel hybrid and protected qubits in a group IV, CMOS-compatible material."}],"language":[{"iso":"eng"}],"oa":1,"file_date_updated":"2024-08-05T08:38:01Z","OA_type":"gold","scopus_import":"1","_id":"17202","date_updated":"2026-04-07T13:01:55Z","citation":{"ista":"Sagi O, Crippa A, Valentini M, Janik M, Baghumyan L, Fabris G, Kapoor L, Hassani F, Fink JM, Calcaterra S, Chrastina D, Isella G, Katsaros G. 2024. A gate tunable transmon qubit in planar Ge. Nature Communications. 15, 6400.","apa":"Sagi, O., Crippa, A., Valentini, M., Janik, M., Baghumyan, L., Fabris, G., … Katsaros, G. (2024). A gate tunable transmon qubit in planar Ge. <i>Nature Communications</i>. Springer Nature. <a href=\"https://doi.org/10.1038/s41467-024-50763-6\">https://doi.org/10.1038/s41467-024-50763-6</a>","ama":"Sagi O, Crippa A, Valentini M, et al. A gate tunable transmon qubit in planar Ge. <i>Nature Communications</i>. 2024;15. doi:<a href=\"https://doi.org/10.1038/s41467-024-50763-6\">10.1038/s41467-024-50763-6</a>","mla":"Sagi, Oliver, et al. “A Gate Tunable Transmon Qubit in Planar Ge.” <i>Nature Communications</i>, vol. 15, 6400, Springer Nature, 2024, doi:<a href=\"https://doi.org/10.1038/s41467-024-50763-6\">10.1038/s41467-024-50763-6</a>.","ieee":"O. Sagi <i>et al.</i>, “A gate tunable transmon qubit in planar Ge,” <i>Nature Communications</i>, vol. 15. Springer Nature, 2024.","chicago":"Sagi, Oliver, Alessandro Crippa, Marco Valentini, Marian Janik, Levon Baghumyan, Giorgio Fabris, Lucky Kapoor, et al. “A Gate Tunable Transmon Qubit in Planar Ge.” <i>Nature Communications</i>. Springer Nature, 2024. <a href=\"https://doi.org/10.1038/s41467-024-50763-6\">https://doi.org/10.1038/s41467-024-50763-6</a>.","short":"O. Sagi, A. Crippa, M. Valentini, M. Janik, L. Baghumyan, G. Fabris, L. Kapoor, F. Hassani, J.M. Fink, S. Calcaterra, D. Chrastina, G. Isella, G. Katsaros, Nature Communications 15 (2024)."},"quality_controlled":"1","DOAJ_listed":"1","acknowledged_ssus":[{"_id":"ScienComp"},{"_id":"M-Shop"},{"_id":"NanoFab"}],"related_material":{"record":[{"status":"public","relation":"research_data","id":"17196"},{"status":"public","id":"18076","relation":"dissertation_contains"}],"link":[{"relation":"erratum","url":"https://doi.org/10.1038/s41467-024-53910-1"}]},"article_number":"6400","ddc":["530"],"external_id":{"pmid":["39080279"],"arxiv":["2403.16774"],"isi":["001281271000022"]},"acknowledgement":"We acknowledge Lucas Casparis, Jeroen Danon, Valla Fatemi, Morten Kjaergard and Javad Shabani for their valuable insights and comments. This research was supported by the Scientific Service Units of ISTA through resources provided by the MIBA Machine Shop\r\nand the Nanofabrication facility. This research and related results were made possible with the support of the NOMIS Foundation and the FWF Projects with DOI:10.55776/I5060 and DOI:10.55776/P36507. We also acknowledge the NextGenerationEU PRIN project\r\n2022A8CJP3 (GAMESQUAD) for partial financial support.","author":[{"id":"71616374-A8E9-11E9-A7CA-09ECE5697425","last_name":"Sagi","full_name":"Sagi, Oliver","first_name":"Oliver"},{"last_name":"Crippa","full_name":"Crippa, Alessandro","first_name":"Alessandro","orcid":"0000-0002-2968-611X","id":"1F2B21A2-F6E7-11E9-9B82-F7DBE5697425"},{"full_name":"Valentini, Marco","first_name":"Marco","last_name":"Valentini","id":"C0BB2FAC-D767-11E9-B658-BC13E6697425"},{"last_name":"Janik","first_name":"Marian","full_name":"Janik, Marian","orcid":"0009-0003-9037-8831","id":"396A1950-F248-11E8-B48F-1D18A9856A87"},{"id":"7aa1f788-b527-11ee-aa9e-e6111a79e0c7","last_name":"Baghumyan","first_name":"Levon","full_name":"Baghumyan, Levon"},{"first_name":"Giorgio","full_name":"Fabris, Giorgio","last_name":"Fabris","id":"298cf6f3-1ff6-11ee-9fa6-d94cfa0b3352"},{"last_name":"Kapoor","first_name":"Lucky","full_name":"Kapoor, Lucky","orcid":"0000-0001-8319-2148","id":"84b9700b-15b2-11ec-abd3-831089e67615"},{"orcid":"0000-0001-6937-5773","id":"2AED110C-F248-11E8-B48F-1D18A9856A87","last_name":"Hassani","full_name":"Hassani, Farid","first_name":"Farid"},{"last_name":"Fink","full_name":"Fink, Johannes M","first_name":"Johannes M","orcid":"0000-0001-8112-028X","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87"},{"last_name":"Calcaterra","first_name":"Stefano","full_name":"Calcaterra, Stefano"},{"last_name":"Chrastina","first_name":"Daniel","full_name":"Chrastina, Daniel"},{"last_name":"Isella","first_name":"Giovanni","full_name":"Isella, Giovanni"},{"first_name":"Georgios","full_name":"Katsaros, Georgios","last_name":"Katsaros","id":"38DB5788-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-8342-202X"}],"title":"A gate tunable transmon qubit in planar Ge","article_processing_charge":"Yes","volume":15,"date_published":"2024-07-30T00:00:00Z","pmid":1,"oa_version":"Published Version","year":"2024","user_id":"317138e5-6ab7-11ef-aa6d-ffef3953e345","publication":"Nature Communications","OA_place":"publisher","publisher":"Springer Nature","arxiv":1,"corr_author":"1","has_accepted_license":"1","status":"public","intvolume":"        15","month":"07","publication_identifier":{"eissn":["2041-1723"]}},{"month":"09","publication_identifier":{"issn":["2663-337X"]},"OA_place":"publisher","publisher":"Institute of Science and Technology Austria","corr_author":"1","status":"public","has_accepted_license":"1","title":"Hybrid circuits on planar Germanium","article_processing_charge":"No","oa_version":"Published Version","date_published":"2024-09-18T00:00:00Z","user_id":"ba8df636-2132-11f1-aed0-ed93e2281fdd","page":"111","year":"2024","ddc":["539"],"author":[{"id":"71616374-A8E9-11E9-A7CA-09ECE5697425","first_name":"Oliver","full_name":"Sagi, Oliver","last_name":"Sagi"}],"_id":"18076","alternative_title":["ISTA Thesis"],"acknowledged_ssus":[{"_id":"NanoFab"},{"_id":"M-Shop"}],"date_updated":"2026-04-16T12:20:39Z","citation":{"ista":"Sagi O. 2024. Hybrid circuits on planar Germanium. Institute of Science and Technology Austria.","apa":"Sagi, O. (2024). <i>Hybrid circuits on planar Germanium</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:18076\">https://doi.org/10.15479/at:ista:18076</a>","ama":"Sagi O. Hybrid circuits on planar Germanium. 2024. doi:<a href=\"https://doi.org/10.15479/at:ista:18076\">10.15479/at:ista:18076</a>","mla":"Sagi, Oliver. <i>Hybrid Circuits on Planar Germanium</i>. Institute of Science and Technology Austria, 2024, doi:<a href=\"https://doi.org/10.15479/at:ista:18076\">10.15479/at:ista:18076</a>.","ieee":"O. Sagi, “Hybrid circuits on planar Germanium,” Institute of Science and Technology Austria, 2024.","chicago":"Sagi, Oliver. “Hybrid Circuits on Planar Germanium.” Institute of Science and Technology Austria, 2024. <a href=\"https://doi.org/10.15479/at:ista:18076\">https://doi.org/10.15479/at:ista:18076</a>.","short":"O. Sagi, Hybrid Circuits on Planar Germanium, Institute of Science and Technology Austria, 2024."},"related_material":{"record":[{"relation":"part_of_dissertation","id":"17202","status":"public"}]},"language":[{"iso":"eng"}],"file_date_updated":"2024-09-19T09:20:33Z","oa":1,"abstract":[{"text":"The new era of Ge has opened up new possibilities in quantum computing. The maturity of Ge\r\nspin qubits is unquestioned, while hybrid semiconductor-superconductor Ge circuits are on track\r\nto enter the game. Gate-tunable transmons (gatemons) employing semiconductor Josephson\r\njunctions have recently emerged as building blocks for such hybrid quantum circuits. In this\r\nthesis, we present a gatemon fabricated in planar Germanium. We induce superconductivity\r\nin a two-dimensional hole gas by evaporating aluminum atop a thin spacer, which separates\r\nthe superconductor from the Ge quantum well. The Josephson junction is then integrated\r\ninto an Xmon circuit and capacitively coupled to a transmission line resonator. We showcase\r\nthe qubit tunability in a broad frequency range with resonator and two-tone spectroscopy.\r\nTime-domain characterizations reveal energy relaxation and coherence times up to 75 ns. Our\r\nresults, combined with the recent advances in the spin qubit field, pave the way towards novel\r\nhybrid and protected qubits in a group IV, CMOS-compatible material.","lang":"eng"}],"license":"https://creativecommons.org/licenses/by-nc-sa/4.0/","ec_funded":1,"project":[{"_id":"bd8bd29e-d553-11ed-ba76-f0070d4b237a","name":"Merging spin and superconducting qubits in planar Ge","grant_number":"P36507"},{"name":"High impedance circuit quantum electrodynamics with hole spins","grant_number":"I05060","_id":"c0977eea-5a5b-11eb-8a69-a862db0cf4d1"},{"name":"Hybrid Semiconductor - Superconductor Quantum Devices","_id":"262116AA-B435-11E9-9278-68D0E5697425"},{"grant_number":"862046","name":"TOPOLOGICALLY PROTECTED AND SCALABLE QUANTUM BITS","_id":"237E5020-32DE-11EA-91FC-C7463DDC885E","call_identifier":"H2020"}],"day":"18","file":[{"content_type":"application/pdf","checksum":"d01d0e2846c2f3ac5bb14d321554a4cd","access_level":"open_access","success":1,"date_updated":"2024-09-18T14:13:01Z","file_name":"OliverSagi_Thesis_pdfa.pdf","file_id":"18093","relation":"main_file","creator":"osagi","date_created":"2024-09-18T14:13:01Z","file_size":86679095},{"content_type":"application/x-zip-compressed","checksum":"0543f473d509ee545f4ed3a56f742f4b","access_level":"local","date_updated":"2024-09-19T09:20:33Z","file_name":"Thesis_OliverSagi.zip","relation":"source_file","file_id":"18094","creator":"osagi","date_created":"2024-09-18T14:14:02Z","file_size":172098524}],"doi":"10.15479/at:ista:18076","department":[{"_id":"GradSch"},{"_id":"GeKa"}],"tmp":{"legal_code_url":"https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode","image":"/images/cc_by_nc_sa.png","name":"Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)","short":"CC BY-NC-SA (4.0)"},"type":"dissertation","date_created":"2024-09-16T12:58:36Z","publication_status":"published","supervisor":[{"id":"38DB5788-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-8342-202X","first_name":"Georgios","full_name":"Katsaros, Georgios","last_name":"Katsaros"}],"degree_awarded":"PhD"},{"oa_version":"Published Version","date_published":"2023-07-21T00:00:00Z","user_id":"ba8df636-2132-11f1-aed0-ed93e2281fdd","year":"2023","page":"184","title":"Mesoscopic phenomena in hybrid semiconductor-superconductor nanodevices : From full-shell nanowires to two-dimensional hole gas in germanium","article_processing_charge":"No","author":[{"last_name":"Valentini","full_name":"Valentini, Marco","first_name":"Marco","id":"C0BB2FAC-D767-11E9-B658-BC13E6697425"}],"ddc":["530"],"publication_identifier":{"issn":["2663-337X"]},"month":"07","corr_author":"1","status":"public","has_accepted_license":"1","OA_place":"publisher","publisher":"Institute of Science and Technology Austria","project":[{"name":"Hybrid Semiconductor - Superconductor Quantum Devices","_id":"262116AA-B435-11E9-9278-68D0E5697425"},{"call_identifier":"H2020","_id":"237E5020-32DE-11EA-91FC-C7463DDC885E","grant_number":"862046","name":"TOPOLOGICALLY PROTECTED AND SCALABLE QUANTUM BITS"},{"grant_number":"F8606","name":"Center for Correlated Quantum Materials and Solid State Quantum Systems: Conventional  and unconventional topological superconductors","_id":"34a66131-11ca-11ed-8bc3-a31681c6b03e"}],"day":"21","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode","image":"/images/cc_by_nc_sa.png","name":"Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)","short":"CC BY-NC-SA (4.0)"},"type":"dissertation","date_created":"2023-07-24T14:10:45Z","publication_status":"published","supervisor":[{"orcid":"0000-0001-8342-202X","id":"38DB5788-F248-11E8-B48F-1D18A9856A87","last_name":"Katsaros","full_name":"Katsaros, Georgios","first_name":"Georgios"}],"degree_awarded":"PhD","file":[{"file_id":"14033","relation":"source_file","creator":"mvalenti","file_size":56121429,"date_created":"2023-08-11T09:27:39Z","content_type":"application/x-zip-compressed","access_level":"closed","checksum":"666ee31c7eade89679806287c062fa14","file_name":"PhD_thesis_Valentini_final.zip","date_updated":"2023-08-11T10:01:34Z"},{"file_id":"14035","relation":"main_file","file_size":38199711,"date_created":"2023-08-11T14:39:17Z","creator":"mvalenti","content_type":"application/pdf","file_name":"PhD_thesis_Valentini_final_validated.pdf","date_updated":"2023-08-11T14:39:17Z","access_level":"open_access","checksum":"0992f2ebef152dee8e70055350ebbb55"}],"doi":"10.15479/at:ista:13286","department":[{"_id":"GradSch"},{"_id":"GeKa"}],"acknowledged_ssus":[{"_id":"NanoFab"},{"_id":"M-Shop"}],"citation":{"apa":"Valentini, M. (2023). <i>Mesoscopic phenomena in hybrid semiconductor-superconductor nanodevices : From full-shell nanowires to two-dimensional hole gas in germanium</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:13286\">https://doi.org/10.15479/at:ista:13286</a>","ama":"Valentini M. Mesoscopic phenomena in hybrid semiconductor-superconductor nanodevices : From full-shell nanowires to two-dimensional hole gas in germanium. 2023. doi:<a href=\"https://doi.org/10.15479/at:ista:13286\">10.15479/at:ista:13286</a>","ista":"Valentini M. 2023. Mesoscopic phenomena in hybrid semiconductor-superconductor nanodevices : From full-shell nanowires to two-dimensional hole gas in germanium. Institute of Science and Technology Austria.","chicago":"Valentini, Marco. “Mesoscopic Phenomena in Hybrid Semiconductor-Superconductor Nanodevices : From Full-Shell Nanowires to Two-Dimensional Hole Gas in Germanium.” Institute of Science and Technology Austria, 2023. <a href=\"https://doi.org/10.15479/at:ista:13286\">https://doi.org/10.15479/at:ista:13286</a>.","short":"M. Valentini, Mesoscopic Phenomena in Hybrid Semiconductor-Superconductor Nanodevices : From Full-Shell Nanowires to Two-Dimensional Hole Gas in Germanium, Institute of Science and Technology Austria, 2023.","mla":"Valentini, Marco. <i>Mesoscopic Phenomena in Hybrid Semiconductor-Superconductor Nanodevices : From Full-Shell Nanowires to Two-Dimensional Hole Gas in Germanium</i>. Institute of Science and Technology Austria, 2023, doi:<a href=\"https://doi.org/10.15479/at:ista:13286\">10.15479/at:ista:13286</a>.","ieee":"M. Valentini, “Mesoscopic phenomena in hybrid semiconductor-superconductor nanodevices : From full-shell nanowires to two-dimensional hole gas in germanium,” Institute of Science and Technology Austria, 2023."},"date_updated":"2026-06-03T07:16:01Z","related_material":{"record":[{"id":"12522","relation":"research_data","status":"public"},{"status":"public","id":"12118","relation":"part_of_dissertation"},{"relation":"part_of_dissertation","id":"8910","status":"public"},{"id":"13312","relation":"part_of_dissertation","status":"public"}]},"_id":"13286","alternative_title":["ISTA Thesis"],"file_date_updated":"2023-08-11T14:39:17Z","oa":1,"language":[{"iso":"eng"}],"abstract":[{"lang":"eng","text":"Semiconductor-superconductor hybrid systems are the harbour of many intriguing mesoscopic phenomena. This material combination leads to spatial variations of the superconducting properties, which gives rise to Andreev bound states (ABSs). Some of these states might exhibit remarkable properties that render them highly desirable for topological quantum computing. The most prominent and hunted of such states are Majorana zero modes (MZMs), quasiparticles equals to their own quasiparticles that they follow non-abelian statistics. In this thesis, we first introduce the general framework of such hybrid systems and, then, we unveil a series of mesoscopic phenomena that we discovered. Firstly, we show tunneling spectroscopy experiments on full-shell nanowires (NWs) showing that unwanted quantum-dot states coupled to superconductors (Yu-Shiba-Rusinov states) can mimic MZMs signatures. Then, we introduce a novel protocol which allowed the integration of tunneling spectroscopy with Coulomb spectroscopy within the same device. Employing this approach on both full-shell NWs and partial-shell NWs, we demonstrated that longitudinally confined states reveal charge transport phenomenology similar to the one expected for MZMs. These findings shed light on the intricate interplay between superconductivity and quantum confinement, which brought us to explore another material platform, i.e. a two-dimensional Germanium hole gas. After developing a robust way to induce superconductivity in such system, we showed how to engineer the proximity effect and we revealed a superconducting hard gap. Finally, we created a superconducting radio frequency driven ideal diode and a generator of non-sinusoidal current-phase relations. Our results open the path for the exploration of protected superconducting qubits and more complex hybrid devices in planar Germanium, like Kitaev chains and hybrid qubit devices."}],"ec_funded":1},{"arxiv":1,"status":"public","publication":"Science","publisher":"American Association for the Advancement of Science","publication_identifier":{"eissn":["1095-9203"],"issn":["0036-8075"]},"main_file_link":[{"url":"https://arxiv.org/abs/2008.02348","open_access":"1"}],"intvolume":"       373","month":"07","author":[{"id":"C0BB2FAC-D767-11E9-B658-BC13E6697425","last_name":"Valentini","full_name":"Valentini, Marco","first_name":"Marco"},{"last_name":"Peñaranda","first_name":"Fernando","full_name":"Peñaranda, Fernando"},{"first_name":"Andrea C","full_name":"Hofmann, Andrea C","last_name":"Hofmann","id":"340F461A-F248-11E8-B48F-1D18A9856A87"},{"id":"33F94E3C-F248-11E8-B48F-1D18A9856A87","first_name":"Matthias","full_name":"Brauns, Matthias","last_name":"Brauns"},{"last_name":"Hauschild","first_name":"Robert","full_name":"Hauschild, Robert","orcid":"0000-0001-9843-3522","id":"4E01D6B4-F248-11E8-B48F-1D18A9856A87"},{"full_name":"Krogstrup, Peter","first_name":"Peter","last_name":"Krogstrup"},{"last_name":"San-Jose","full_name":"San-Jose, Pablo","first_name":"Pablo"},{"last_name":"Prada","first_name":"Elsa","full_name":"Prada, Elsa"},{"last_name":"Aguado","full_name":"Aguado, Ramón","first_name":"Ramón"},{"last_name":"Katsaros","first_name":"Georgios","full_name":"Katsaros, Georgios","orcid":"0000-0001-8342-202X","id":"38DB5788-F248-11E8-B48F-1D18A9856A87"}],"acknowledgement":"The authors thank A. Higginbotham, E. J. H. Lee and F. R. Martins for helpful discussions. This research was supported by the Scientific Service Units of IST Austria through resources provided by the MIBA Machine Shop and the nanofabrication facility; the NOMIS Foundation and Microsoft; the European Union’s Horizon 2020 research and innovation program under the Marie SklodowskaCurie grant agreement No 844511; the FETOPEN Grant Agreement No. 828948; the European Research Commission through the grant agreement HEMs-DAM No 716655; the Spanish Ministry of Science and Innovation through Grants PGC2018-097018-B-I00, PCI2018-093026, FIS2016-80434-P (AEI/FEDER, EU), RYC2011-09345 (Ram´on y Cajal Programme), and the Mar´ıa de Maeztu Programme for Units of Excellence in R&D (CEX2018-000805-M); the CSIC Research Platform on Quantum Technologies PTI-001.","external_id":{"isi":["000677843100034"],"arxiv":["2008.02348"],"pmid":["34210881"]},"article_number":"82-88","oa_version":"Submitted Version","pmid":1,"volume":373,"date_published":"2021-07-02T00:00:00Z","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","year":"2021","title":"Nontopological zero-bias peaks in full-shell nanowires induced by flux-tunable Andreev states","article_processing_charge":"No","scopus_import":"1","language":[{"iso":"eng"}],"oa":1,"abstract":[{"text":"A semiconducting nanowire fully wrapped by a superconducting shell has been proposed as a platform for obtaining Majorana modes at small magnetic fields. In this study, we demonstrate that the appearance of subgap states in such structures is actually governed by the junction region in tunneling spectroscopy measurements and not the full-shell nanowire itself. Short tunneling regions never show subgap states, whereas longer junctions always do. This can be understood in terms of quantum dots forming in the junction and hosting Andreev levels in the Yu-Shiba-Rusinov regime. The intricate magnetic field dependence of the Andreev levels, through both the Zeeman and Little-Parks effects, may result in robust zero-bias peaks—features that could be easily misinterpreted as originating from Majorana zero modes but are unrelated to topological superconductivity.","lang":"eng"}],"ec_funded":1,"acknowledged_ssus":[{"_id":"M-Shop"},{"_id":"NanoFab"}],"citation":{"ista":"Valentini M, Peñaranda F, Hofmann AC, Brauns M, Hauschild R, Krogstrup P, San-Jose P, Prada E, Aguado R, Katsaros G. 2021. Nontopological zero-bias peaks in full-shell nanowires induced by flux-tunable Andreev states. Science. 373(6550), 82–88.","apa":"Valentini, M., Peñaranda, F., Hofmann, A. C., Brauns, M., Hauschild, R., Krogstrup, P., … Katsaros, G. (2021). Nontopological zero-bias peaks in full-shell nanowires induced by flux-tunable Andreev states. <i>Science</i>. American Association for the Advancement of Science. <a href=\"https://doi.org/10.1126/science.abf1513\">https://doi.org/10.1126/science.abf1513</a>","ama":"Valentini M, Peñaranda F, Hofmann AC, et al. Nontopological zero-bias peaks in full-shell nanowires induced by flux-tunable Andreev states. <i>Science</i>. 2021;373(6550). doi:<a href=\"https://doi.org/10.1126/science.abf1513\">10.1126/science.abf1513</a>","mla":"Valentini, Marco, et al. “Nontopological Zero-Bias Peaks in Full-Shell Nanowires Induced by Flux-Tunable Andreev States.” <i>Science</i>, vol. 373, no. 6550, 82–88, American Association for the Advancement of Science, 2021, doi:<a href=\"https://doi.org/10.1126/science.abf1513\">10.1126/science.abf1513</a>.","ieee":"M. Valentini <i>et al.</i>, “Nontopological zero-bias peaks in full-shell nanowires induced by flux-tunable Andreev states,” <i>Science</i>, vol. 373, no. 6550. American Association for the Advancement of Science, 2021.","chicago":"Valentini, Marco, Fernando Peñaranda, Andrea C Hofmann, Matthias Brauns, Robert Hauschild, Peter Krogstrup, Pablo San-Jose, Elsa Prada, Ramón Aguado, and Georgios Katsaros. “Nontopological Zero-Bias Peaks in Full-Shell Nanowires Induced by Flux-Tunable Andreev States.” <i>Science</i>. American Association for the Advancement of Science, 2021. <a href=\"https://doi.org/10.1126/science.abf1513\">https://doi.org/10.1126/science.abf1513</a>.","short":"M. Valentini, F. Peñaranda, A.C. Hofmann, M. Brauns, R. Hauschild, P. Krogstrup, P. San-Jose, E. Prada, R. Aguado, G. Katsaros, Science 373 (2021)."},"quality_controlled":"1","date_updated":"2026-04-07T13:27:22Z","related_material":{"record":[{"id":"9389","relation":"research_data","status":"public"},{"id":"13286","relation":"dissertation_contains","status":"public"}],"link":[{"description":"News on IST Homepage","relation":"press_release","url":"https://ist.ac.at/en/news/unfinding-a-split-electron/"}]},"issue":"6550","_id":"8910","type":"journal_article","publication_status":"published","date_created":"2020-12-02T10:51:52Z","department":[{"_id":"GeKa"},{"_id":"Bio"}],"doi":"10.1126/science.abf1513","article_type":"original","project":[{"_id":"262116AA-B435-11E9-9278-68D0E5697425","name":"Hybrid Semiconductor - Superconductor Quantum Devices"},{"name":"Majorana bound states in Ge/SiGe heterostructures","grant_number":"844511","call_identifier":"H2020","_id":"26A151DA-B435-11E9-9278-68D0E5697425"}],"day":"02","isi":1},{"article_type":"original","project":[{"call_identifier":"H2020","_id":"26A151DA-B435-11E9-9278-68D0E5697425","name":"Majorana bound states in Ge/SiGe heterostructures","grant_number":"844511"},{"grant_number":"754411","name":"ISTplus - Postdoctoral Fellowships","_id":"260C2330-B435-11E9-9278-68D0E5697425","call_identifier":"H2020"},{"call_identifier":"FWF","_id":"2641CE5E-B435-11E9-9278-68D0E5697425","grant_number":"P30207","name":"Hole spin orbit qubits in Ge quantum wells"},{"name":"Hybrid Semiconductor - Superconductor Quantum Devices","_id":"262116AA-B435-11E9-9278-68D0E5697425"}],"day":"01","isi":1,"date_created":"2020-12-02T10:50:47Z","publication_status":"published","type":"journal_article","doi":"10.1038/s41563-021-01022-2","department":[{"_id":"GeKa"},{"_id":"NanoFab"},{"_id":"GradSch"}],"date_updated":"2026-07-08T22:30:50Z","citation":{"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.","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.","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>.","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>","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."},"quality_controlled":"1","acknowledged_ssus":[{"_id":"M-Shop"},{"_id":"NanoFab"}],"related_material":{"record":[{"status":"public","id":"9323","relation":"research_data"},{"status":"public","id":"10058","relation":"dissertation_contains"}],"link":[{"url":"https://ist.ac.at/en/news/quantum-computing-with-holes/","relation":"press_release","description":"News on IST Homepage"}]},"_id":"8909","issue":"8","scopus_import":"1","abstract":[{"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.","lang":"eng"}],"language":[{"iso":"eng"}],"oa":1,"ec_funded":1,"oa_version":"Preprint","volume":20,"date_published":"2021-08-01T00:00:00Z","pmid":1,"page":"1106–1112","year":"2021","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","title":"A singlet triplet hole spin qubit in planar Ge","article_processing_charge":"No","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.","author":[{"first_name":"Daniel","full_name":"Jirovec, Daniel","last_name":"Jirovec","id":"4C473F58-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-7197-4801"},{"id":"340F461A-F248-11E8-B48F-1D18A9856A87","first_name":"Andrea C","full_name":"Hofmann, Andrea C","last_name":"Hofmann"},{"last_name":"Ballabio","full_name":"Ballabio, Andrea","first_name":"Andrea"},{"first_name":"Philipp M.","full_name":"Mutter, Philipp M.","last_name":"Mutter"},{"last_name":"Tavani","full_name":"Tavani, Giulio","first_name":"Giulio"},{"last_name":"Botifoll","first_name":"Marc","full_name":"Botifoll, Marc"},{"full_name":"Crippa, Alessandro","first_name":"Alessandro","last_name":"Crippa","id":"1F2B21A2-F6E7-11E9-9B82-F7DBE5697425","orcid":"0000-0002-2968-611X"},{"last_name":"Kukucka","first_name":"Josip","full_name":"Kukucka, Josip","id":"3F5D8856-F248-11E8-B48F-1D18A9856A87"},{"first_name":"Oliver","full_name":"Sagi, Oliver","last_name":"Sagi","id":"71616374-A8E9-11E9-A7CA-09ECE5697425"},{"orcid":"0000-0003-2668-2401","id":"38F80F9A-1CB8-11EA-BC76-B49B3DDC885E","last_name":"Martins","full_name":"Martins, Frederico","first_name":"Frederico"},{"last_name":"Saez Mollejo","first_name":"Jaime","full_name":"Saez Mollejo, Jaime","id":"e0390f72-f6e0-11ea-865d-862393336714"},{"id":"2A307FE2-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-7370-5357","full_name":"Prieto Gonzalez, Ivan","first_name":"Ivan","last_name":"Prieto Gonzalez"},{"full_name":"Borovkov, Maksim","first_name":"Maksim","last_name":"Borovkov","id":"2ac7a0a2-3562-11eb-9256-fbd18ea55087"},{"full_name":"Arbiol, Jordi","first_name":"Jordi","last_name":"Arbiol"},{"first_name":"Daniel","full_name":"Chrastina, Daniel","last_name":"Chrastina"},{"last_name":"Isella","full_name":"Isella, Giovanni","first_name":"Giovanni"},{"last_name":"Katsaros","first_name":"Georgios","full_name":"Katsaros, Georgios","orcid":"0000-0001-8342-202X","id":"38DB5788-F248-11E8-B48F-1D18A9856A87"}],"external_id":{"isi":["000657596400001"],"pmid":["34083775"],"arxiv":["2011.13755"]},"main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/2011.13755"}],"publication_identifier":{"eissn":["1476-4660"],"issn":["1476-1122"]},"intvolume":"        20","month":"08","corr_author":"1","arxiv":1,"status":"public","publication":"Nature Materials","publisher":"Springer Nature"},{"publication":"arXiv","has_accepted_license":"1","status":"public","corr_author":"1","arxiv":1,"month":"12","ddc":["530"],"article_number":"2012.00322","external_id":{"arxiv":["2012.00322"]},"acknowledgement":"This research and related results were made possible with the support of the NOMIS Foundation. This research was supported by the Scientific Service Units of IST Austria through resources provided by the MIBA Machine Shop and the nanofabrication facility, the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement #844511 and the Grant Agreement #862046. ICN2 acknowledge funding from Generalitat de Catalunya 2017 SGR 327. ICN2 is supported by the Severo Ochoa\r\nprogram from Spanish MINECO (Grant No. SEV2017-0706) and is funded by the CERCA Programme / Generalitat de Catalunya. Part of the present work has been performed in the framework of Universitat Aut`onoma de Barcelona Materials Science PhD program. The HAADF-STEM microscopy was conducted in the Laboratorio de Microscopias Avanzadas at Instituto de Nanociencia de Aragon-Universidad de Zaragoza. Authors acknowledge the LMA-INA for offering access to their instruments and expertise. We acknowledge support from CSIC Research Platform on Quantum Technologies PTI-001. This project has received funding from\r\nthe European Union’s Horizon 2020 research and innovation programme under grant agreement No 823717 – ESTEEM3. M.B. acknowledges support from SUR Generalitat de Catalunya and the EU Social Fund; project ref. 2020 FI 00103. GS and MV acknowledge support through a projectruimte grant associated with the Netherlands Organization of Scientific Research (NWO).","author":[{"full_name":"Aggarwal, Kushagra","first_name":"Kushagra","last_name":"Aggarwal","id":"b22ab905-3539-11eb-84c3-fc159dcd79cb","orcid":"0000-0001-9985-9293"},{"id":"340F461A-F248-11E8-B48F-1D18A9856A87","full_name":"Hofmann, Andrea C","first_name":"Andrea C","last_name":"Hofmann"},{"id":"4C473F58-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-7197-4801","full_name":"Jirovec, Daniel","first_name":"Daniel","last_name":"Jirovec"},{"first_name":"Ivan","full_name":"Prieto Gonzalez, Ivan","last_name":"Prieto Gonzalez","id":"2A307FE2-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-7370-5357"},{"first_name":"Amir","full_name":"Sammak, Amir","last_name":"Sammak"},{"first_name":"Marc","full_name":"Botifoll, Marc","last_name":"Botifoll"},{"full_name":"Marti-Sanchez, Sara","first_name":"Sara","last_name":"Marti-Sanchez"},{"last_name":"Veldhorst","full_name":"Veldhorst, Menno","first_name":"Menno"},{"last_name":"Arbiol","full_name":"Arbiol, Jordi","first_name":"Jordi"},{"full_name":"Scappucci, Giordano","first_name":"Giordano","last_name":"Scappucci"},{"orcid":"0000-0001-8342-202X","id":"38DB5788-F248-11E8-B48F-1D18A9856A87","last_name":"Katsaros","first_name":"Georgios","full_name":"Katsaros, Georgios"}],"article_processing_charge":"No","title":"Enhancement of proximity induced superconductivity in planar Germanium","year":"2020","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","date_published":"2020-12-02T00:00:00Z","oa_version":"Submitted Version","ec_funded":1,"abstract":[{"lang":"eng","text":"Holes in planar Ge have high mobilities, strong spin-orbit interaction and electrically tunable g-factors, and are therefore emerging as a promising candidate for hybrid superconductorsemiconductor devices. This is further motivated by the observation of supercurrent transport in planar Ge Josephson Field effect transistors (JoFETs). A key challenge towards hybrid germanium quantum technology is the design of high quality interfaces and superconducting contacts that are robust against magnetic fields. By combining the assets of Al, which has a long superconducting coherence, and Nb, which has a significant superconducting gap, we form low-disordered JoFETs with large ICRN products that are capable of withstanding high magnetic fields. We furthermore demonstrate the ability of phase-biasing individual JoFETs opening up an avenue to explore topological superconductivity in planar Ge. The persistence of superconductivity in the reported hybrid devices beyond 1.8 T paves the way towards integrating spin qubits and proximity-induced superconductivity on the same chip."}],"oa":1,"language":[{"iso":"eng"}],"file_date_updated":"2020-12-02T10:42:31Z","_id":"8831","related_material":{"record":[{"relation":"later_version","id":"10559","status":"public"},{"status":"public","relation":"research_data","id":"8834"},{"relation":"dissertation_contains","id":"10058","status":"public"}]},"date_updated":"2026-07-08T22:30:50Z","citation":{"chicago":"Aggarwal, Kushagra, Andrea C Hofmann, Daniel Jirovec, Ivan Prieto Gonzalez, Amir Sammak, Marc Botifoll, Sara Marti-Sanchez, et al. “Enhancement of Proximity Induced Superconductivity in Planar Germanium.” <i>ArXiv</i>, n.d. <a href=\"https://doi.org/10.48550/arXiv.2012.00322\">https://doi.org/10.48550/arXiv.2012.00322</a>.","short":"K. Aggarwal, A.C. Hofmann, D. Jirovec, I. Prieto Gonzalez, A. Sammak, M. Botifoll, S. Marti-Sanchez, M. Veldhorst, J. Arbiol, G. Scappucci, G. Katsaros, ArXiv (n.d.).","mla":"Aggarwal, Kushagra, et al. “Enhancement of Proximity Induced Superconductivity in Planar Germanium.” <i>ArXiv</i>, 2012.00322, doi:<a href=\"https://doi.org/10.48550/arXiv.2012.00322\">10.48550/arXiv.2012.00322</a>.","ieee":"K. Aggarwal <i>et al.</i>, “Enhancement of proximity induced superconductivity in planar Germanium,” <i>arXiv</i>. .","apa":"Aggarwal, K., Hofmann, A. C., Jirovec, D., Prieto Gonzalez, I., Sammak, A., Botifoll, M., … Katsaros, G. (n.d.). Enhancement of proximity induced superconductivity in planar Germanium. <i>arXiv</i>. <a href=\"https://doi.org/10.48550/arXiv.2012.00322\">https://doi.org/10.48550/arXiv.2012.00322</a>","ama":"Aggarwal K, Hofmann AC, Jirovec D, et al. Enhancement of proximity induced superconductivity in planar Germanium. <i>arXiv</i>. doi:<a href=\"https://doi.org/10.48550/arXiv.2012.00322\">10.48550/arXiv.2012.00322</a>","ista":"Aggarwal K, Hofmann AC, Jirovec D, Prieto Gonzalez I, Sammak A, Botifoll M, Marti-Sanchez S, Veldhorst M, Arbiol J, Scappucci G, Katsaros G. Enhancement of proximity induced superconductivity in planar Germanium. arXiv, 2012.00322."},"acknowledged_ssus":[{"_id":"M-Shop"},{"_id":"NanoFab"}],"doi":"10.48550/arXiv.2012.00322","department":[{"_id":"GeKa"}],"file":[{"content_type":"application/pdf","file_name":"Superconducting_2D_Ge.pdf","date_updated":"2020-12-02T10:42:31Z","access_level":"open_access","checksum":"22a612e206232fa94b138b2c2f957582","file_id":"8832","relation":"main_file","file_size":1697939,"date_created":"2020-12-02T10:42:31Z","creator":"gkatsaro"}],"publication_status":"draft","date_created":"2020-12-02T10:42:53Z","type":"preprint","day":"02","project":[{"_id":"262116AA-B435-11E9-9278-68D0E5697425","name":"Hybrid Semiconductor - Superconductor Quantum Devices"},{"name":"Majorana bound states in Ge/SiGe heterostructures","grant_number":"844511","call_identifier":"H2020","_id":"26A151DA-B435-11E9-9278-68D0E5697425"},{"grant_number":"862046","name":"TOPOLOGICALLY PROTECTED AND SCALABLE QUANTUM BITS","_id":"237E5020-32DE-11EA-91FC-C7463DDC885E","call_identifier":"H2020"}]}]