---
_id: '8910'
abstract:
- lang: eng
  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.
acknowledged_ssus:
- _id: M-Shop
- _id: NanoFab
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.
article_number: 82-88
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Marco
  full_name: Valentini, Marco
  id: C0BB2FAC-D767-11E9-B658-BC13E6697425
  last_name: Valentini
- first_name: Fernando
  full_name: Peñaranda, Fernando
  last_name: Peñaranda
- first_name: Andrea C
  full_name: Hofmann, Andrea C
  id: 340F461A-F248-11E8-B48F-1D18A9856A87
  last_name: Hofmann
- first_name: Matthias
  full_name: Brauns, Matthias
  id: 33F94E3C-F248-11E8-B48F-1D18A9856A87
  last_name: Brauns
- first_name: Robert
  full_name: Hauschild, Robert
  id: 4E01D6B4-F248-11E8-B48F-1D18A9856A87
  last_name: Hauschild
  orcid: 0000-0001-9843-3522
- first_name: Peter
  full_name: Krogstrup, Peter
  last_name: Krogstrup
- first_name: Pablo
  full_name: San-Jose, Pablo
  last_name: San-Jose
- first_name: Elsa
  full_name: Prada, Elsa
  last_name: Prada
- first_name: Ramón
  full_name: Aguado, Ramón
  last_name: Aguado
- first_name: Georgios
  full_name: Katsaros, Georgios
  id: 38DB5788-F248-11E8-B48F-1D18A9856A87
  last_name: Katsaros
  orcid: 0000-0001-8342-202X
citation:
  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>
  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>
  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>.
  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.
  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.
  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>.
  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).
date_created: 2020-12-02T10:51:52Z
date_published: 2021-07-02T00:00:00Z
date_updated: 2024-02-21T12:40:09Z
day: '02'
department:
- _id: GeKa
- _id: Bio
doi: 10.1126/science.abf1513
ec_funded: 1
external_id:
  arxiv:
  - '2008.02348'
  isi:
  - '000677843100034'
intvolume: '       373'
isi: 1
issue: '6550'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/2008.02348
month: '07'
oa: 1
oa_version: Submitted Version
project:
- _id: 262116AA-B435-11E9-9278-68D0E5697425
  name: Hybrid Semiconductor - Superconductor Quantum Devices
- _id: 26A151DA-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '844511'
  name: Majorana bound states in Ge/SiGe heterostructures
publication: Science
publication_identifier:
  eissn:
  - '10959203'
  issn:
  - '00368075'
publication_status: published
publisher: American Association for the Advancement of Science
quality_controlled: '1'
related_material:
  link:
  - description: News on IST Homepage
    relation: press_release
    url: https://ist.ac.at/en/news/unfinding-a-split-electron/
  record:
  - id: '13286'
    relation: dissertation_contains
    status: public
  - id: '9389'
    relation: research_data
    status: public
scopus_import: '1'
status: public
title: Nontopological zero-bias peaks in full-shell nanowires induced by flux-tunable
  Andreev states
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 373
year: '2021'
...
---
_id: '317'
abstract:
- lang: eng
  text: We replace the established aluminium gates for the formation of quantum dots
    in silicon with gates made from palladium. We study the morphology of both aluminium
    and palladium gates with transmission electron microscopy. The native aluminium
    oxide is found to be formed all around the aluminium gates, which could lead to
    the formation of unintentional dots. Therefore, we report on a novel fabrication
    route that replaces aluminium and its native oxide by palladium with atomic-layer-deposition-grown
    aluminium oxide. Using this approach, we show the formation of low-disorder gate-defined
    quantum dots, which are reproducibly fabricated. Furthermore, palladium enables
    us to further shrink the gate design, allowing us to perform electron transport
    measurements in the few-electron regime in devices comprising only two gate layers,
    a major technological advancement. It remains to be seen, whether the introduction
    of palladium gates can improve the excellent results on electron and nuclear spin
    qubits defined with an aluminium gate stack.
article_number: '5690'
article_processing_charge: No
author:
- first_name: Matthias
  full_name: Brauns, Matthias
  id: 33F94E3C-F248-11E8-B48F-1D18A9856A87
  last_name: Brauns
- first_name: Sergey
  full_name: Amitonov, Sergey
  last_name: Amitonov
- first_name: Paul
  full_name: Spruijtenburg, Paul
  last_name: Spruijtenburg
- first_name: Floris
  full_name: Zwanenburg, Floris
  last_name: Zwanenburg
citation:
  ama: Brauns M, Amitonov S, Spruijtenburg P, Zwanenburg F. Palladium gates for reproducible
    quantum dots in silicon. <i>Scientific Reports</i>. 2018;8(1). doi:<a href="https://doi.org/10.1038/s41598-018-24004-y">10.1038/s41598-018-24004-y</a>
  apa: Brauns, M., Amitonov, S., Spruijtenburg, P., &#38; Zwanenburg, F. (2018). Palladium
    gates for reproducible quantum dots in silicon. <i>Scientific Reports</i>. Nature
    Publishing Group. <a href="https://doi.org/10.1038/s41598-018-24004-y">https://doi.org/10.1038/s41598-018-24004-y</a>
  chicago: Brauns, Matthias, Sergey Amitonov, Paul Spruijtenburg, and Floris Zwanenburg.
    “Palladium Gates for Reproducible Quantum Dots in Silicon.” <i>Scientific Reports</i>.
    Nature Publishing Group, 2018. <a href="https://doi.org/10.1038/s41598-018-24004-y">https://doi.org/10.1038/s41598-018-24004-y</a>.
  ieee: M. Brauns, S. Amitonov, P. Spruijtenburg, and F. Zwanenburg, “Palladium gates
    for reproducible quantum dots in silicon,” <i>Scientific Reports</i>, vol. 8,
    no. 1. Nature Publishing Group, 2018.
  ista: Brauns M, Amitonov S, Spruijtenburg P, Zwanenburg F. 2018. Palladium gates
    for reproducible quantum dots in silicon. Scientific Reports. 8(1), 5690.
  mla: Brauns, Matthias, et al. “Palladium Gates for Reproducible Quantum Dots in
    Silicon.” <i>Scientific Reports</i>, vol. 8, no. 1, 5690, Nature Publishing Group,
    2018, doi:<a href="https://doi.org/10.1038/s41598-018-24004-y">10.1038/s41598-018-24004-y</a>.
  short: M. Brauns, S. Amitonov, P. Spruijtenburg, F. Zwanenburg, Scientific Reports
    8 (2018).
date_created: 2018-12-11T11:45:47Z
date_published: 2018-04-09T00:00:00Z
date_updated: 2023-09-13T09:38:00Z
day: '09'
ddc:
- '539'
department:
- _id: GeKa
doi: 10.1038/s41598-018-24004-y
external_id:
  isi:
  - '000429404300013'
file:
- access_level: open_access
  checksum: 20af238ca4ba6491b77270be8d826bf5
  content_type: application/pdf
  creator: system
  date_created: 2018-12-12T10:17:04Z
  date_updated: 2020-07-14T12:46:02Z
  file_id: '5256'
  file_name: IST-2018-1016-v1+1_2018_Brauns_Palladium_gates.pdf
  file_size: 1850530
  relation: main_file
file_date_updated: 2020-07-14T12:46:02Z
has_accepted_license: '1'
intvolume: '         8'
isi: 1
issue: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by/4.0/
month: '04'
oa: 1
oa_version: Published Version
publication: Scientific Reports
publication_status: published
publisher: Nature Publishing Group
publist_id: '7548'
pubrep_id: '1016'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Palladium gates for reproducible quantum dots in silicon
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: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 8
year: '2018'
...
---
_id: '5990'
abstract:
- lang: eng
  text: 'A Ge–Si core–shell nanowire is used to realize a Josephson field‐effect transistor
    with highly transparent contacts to superconducting leads. By changing the electric
    field, access to two distinct regimes, not combined before in a single device,
    is gained: in the accumulation mode the device is highly transparent and the supercurrent
    is carried by multiple subbands, while near depletion, the supercurrent is carried
    by single‐particle levels of a strongly coupled quantum dot operating in the few‐hole
    regime. These results establish Ge–Si nanowires as an important platform for hybrid
    superconductor–semiconductor physics and Majorana fermions.'
article_number: '1802257'
article_processing_charge: No
arxiv: 1
author:
- first_name: Joost
  full_name: Ridderbos, Joost
  last_name: Ridderbos
- first_name: Matthias
  full_name: Brauns, Matthias
  id: 33F94E3C-F248-11E8-B48F-1D18A9856A87
  last_name: Brauns
- first_name: Jie
  full_name: Shen, Jie
  last_name: Shen
- first_name: Folkert K.
  full_name: de Vries, Folkert K.
  last_name: de Vries
- first_name: Ang
  full_name: Li, Ang
  last_name: Li
- first_name: Erik P. A. M.
  full_name: Bakkers, Erik P. A. M.
  last_name: Bakkers
- first_name: Alexander
  full_name: Brinkman, Alexander
  last_name: Brinkman
- first_name: Floris A.
  full_name: Zwanenburg, Floris A.
  last_name: Zwanenburg
citation:
  ama: Ridderbos J, Brauns M, Shen J, et al. Josephson effect in a few-hole quantum
    dot. <i>Advanced Materials</i>. 2018;30(44). doi:<a href="https://doi.org/10.1002/adma.201802257">10.1002/adma.201802257</a>
  apa: Ridderbos, J., Brauns, M., Shen, J., de Vries, F. K., Li, A., Bakkers, E. P.
    A. M., … Zwanenburg, F. A. (2018). Josephson effect in a few-hole quantum dot.
    <i>Advanced Materials</i>. Wiley. <a href="https://doi.org/10.1002/adma.201802257">https://doi.org/10.1002/adma.201802257</a>
  chicago: Ridderbos, Joost, Matthias Brauns, Jie Shen, Folkert K. de Vries, Ang Li,
    Erik P. A. M. Bakkers, Alexander Brinkman, and Floris A. Zwanenburg. “Josephson
    Effect in a Few-Hole Quantum Dot.” <i>Advanced Materials</i>. Wiley, 2018. <a
    href="https://doi.org/10.1002/adma.201802257">https://doi.org/10.1002/adma.201802257</a>.
  ieee: J. Ridderbos <i>et al.</i>, “Josephson effect in a few-hole quantum dot,”
    <i>Advanced Materials</i>, vol. 30, no. 44. Wiley, 2018.
  ista: Ridderbos J, Brauns M, Shen J, de Vries FK, Li A, Bakkers EPAM, Brinkman A,
    Zwanenburg FA. 2018. Josephson effect in a few-hole quantum dot. Advanced Materials.
    30(44), 1802257.
  mla: Ridderbos, Joost, et al. “Josephson Effect in a Few-Hole Quantum Dot.” <i>Advanced
    Materials</i>, vol. 30, no. 44, 1802257, Wiley, 2018, doi:<a href="https://doi.org/10.1002/adma.201802257">10.1002/adma.201802257</a>.
  short: J. Ridderbos, M. Brauns, J. Shen, F.K. de Vries, A. Li, E.P.A.M. Bakkers,
    A. Brinkman, F.A. Zwanenburg, Advanced Materials 30 (2018).
date_created: 2019-02-14T12:14:26Z
date_published: 2018-11-02T00:00:00Z
date_updated: 2023-09-19T14:29:58Z
day: '02'
department:
- _id: GeKa
doi: 10.1002/adma.201802257
external_id:
  arxiv:
  - '1809.08487'
  isi:
  - '000450232800015'
intvolume: '        30'
isi: 1
issue: '44'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/1809.08487
month: '11'
oa: 1
oa_version: Preprint
publication: Advanced Materials
publication_identifier:
  issn:
  - 0935-9648
publication_status: published
publisher: Wiley
quality_controlled: '1'
scopus_import: '1'
status: public
title: Josephson effect in a few-hole quantum dot
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 30
year: '2018'
...