---
OA_place: repository
OA_type: green
_id: '22619'
abstract:
- lang: eng
  text: Planar germanium is currently the only semiconducting platform where high-coherence
    spin qubits and proximity-induced superconductivity have each been demonstrated.
    Recent research into spin qubits in Ge/SiGe heterostructures has focused on increasing
    the thickness of the SiGe capping layer, reporting improvements in the electrostatic
    noise levels. Meanwhile, heterostructures with thinner capping layers remain rather
    unexplored, despite the potential advantages for proximity-induced superconductivity.
    Here, we study a Ge/SiGe heterostructure with a thin SiGe cap d - 4nm and investigate
    its viability to host low-noise quantum dots. To keep the thermal budget compatible
    with superconducting layers, low-temperature oxide deposition processes were developed
    and implemented for the gate dielectrics. The charge noise level of the fabricated
    devices is estimated to be 1.8  +- 1.0 μeV/ square HZ⁠, comparable to devices
    fabricated on shallow heterostructures (⁠ d - 20nm⁠) with high-temperature deposited
    oxides. Low charge noise levels, together with the straightforward integration
    of superconductors, make this heterostructure an attractive platform for prototyping
    hybrid semiconducting–superconducting devices.
acknowledged_ssus:
- _id: M-Shop
- _id: NanoFab
acknowledgement: 'We sincerely thank Nick van Loo, Greg Mazur, Dhananjay Joshi, and
  Srijit Goswami for their inputs on low-temperature HfOx deposition; Matias Urdampilleta
  and Daniel Jirovec for discussions; and Kristen Léonard for the careful reading
  of the manuscript. This research was supported by the Scientific Service Units of
  ISTA through resources provided by the Miba Machine Shop and the Nanofabrication
  facility. The authors acknowledge support from the NOMIS Foundation; the European
  Innovation Council Pathfinder Grant No. 101115315 (QuKiT); the FWF Projects with
  DOI:10.55776/F86, DOI:10.55776/PAT7682124, and DOI:10.55776/P36507; and the HE-MSCA-PF
  project with DOI:10.3030/101150858. ICN2 is supported by the Severo Ochoa Program
  from Spanish MCIN/AEI (Grant No.: CEX2021-001214-S) and is funded by the CERCA Program/Generalitat
  de Catalunya. ICN2 acknowledges funding from Generalitat de Catalunya (No. 2021SGR00457).
  We acknowledge support from the CSIC Interdisciplinary Thematic Platform (PTI+)
  on Quantum Technologies (PTI-QTEP+).'
article_number: '033505'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Maksim
  full_name: Borovkov, Maksim
  id: 1fd0975f-8b61-11ed-b69e-d149334f28c5
  last_name: Borovkov
- first_name: Yona A
  full_name: Schell, Yona A
  id: fe39122d-06bb-11ec-a33b-9e22b40e40a5
  last_name: Schell
- first_name: Dina
  full_name: Sokolova, Dina
  id: 2d2d62f8-72f0-11ef-b75a-8ec3e8a60032
  last_name: Sokolova
- first_name: Kevin Etienne Robert
  full_name: Roux, Kevin Etienne Robert
  id: 53f93ea2-803f-11ed-ab7e-b283135794ef
  last_name: Roux
- first_name: Paul
  full_name: Falthansl-Scheinecker, Paul
  id: 85b43b21-15b2-11ec-abd3-e2c252cc2285
  last_name: Falthansl-Scheinecker
- first_name: Giorgio
  full_name: Fabris, Giorgio
  id: 298cf6f3-1ff6-11ee-9fa6-d94cfa0b3352
  last_name: Fabris
- first_name: Devashish C
  full_name: Shah, Devashish C
  id: de191434-4e7e-11ef-bf4b-9a056fc19fc3
  last_name: Shah
  orcid: 0009-0007-5829-7707
- first_name: Jaime
  full_name: Saez Mollejo, Jaime
  id: e0390f72-f6e0-11ea-865d-862393336714
  last_name: Saez Mollejo
- first_name: Rodolfo
  full_name: Previdi, Rodolfo
  id: bc4ea1dc-00ce-11ec-8a4e-b325ca8b9876
  last_name: Previdi
- first_name: Inas
  full_name: Taha, Inas
  last_name: Taha
- first_name: Aziz
  full_name: Genç, Aziz
  last_name: Genç
- first_name: Jordi
  full_name: Arbiol, Jordi
  last_name: Arbiol
- first_name: Stefano
  full_name: Calcaterra, Stefano
  last_name: Calcaterra
- first_name: Afonso De Cerdeira
  full_name: Oliveira, Afonso De Cerdeira
  last_name: Oliveira
- first_name: Daniel
  full_name: Chrastina, Daniel
  last_name: Chrastina
- first_name: Giovanni
  full_name: Isella, Giovanni
  last_name: Isella
- first_name: Anton
  full_name: Bubis, Anton
  id: 1f6212b5-f795-11ec-9c0c-de4780302890
  last_name: Bubis
- first_name: Georgios
  full_name: Katsaros, Georgios
  id: 38DB5788-F248-11E8-B48F-1D18A9856A87
  last_name: Katsaros
  orcid: 0000-0001-8342-202X
citation:
  ama: Borovkov M, Schell YA, Sokolova D, et al. Low-noise quantum dots in ultra-shallow
    Ge/SiGe heterostructures for prototyping hybrid semiconducting–superconducting
    devices. <i>Applied Physics Letters</i>. 2026;129(3). doi:<a href="https://doi.org/10.1063/5.0333142">10.1063/5.0333142</a>
  apa: Borovkov, M., Schell, Y. A., Sokolova, D., Roux, K. E. R., Falthansl-Scheinecker,
    P., Fabris, G., … Katsaros, G. (2026). Low-noise quantum dots in ultra-shallow
    Ge/SiGe heterostructures for prototyping hybrid semiconducting–superconducting
    devices. <i>Applied Physics Letters</i>. AIP Publishing. <a href="https://doi.org/10.1063/5.0333142">https://doi.org/10.1063/5.0333142</a>
  chicago: Borovkov, Maksim, Yona A Schell, Dina Sokolova, Kevin Etienne Robert Roux,
    Paul Falthansl-Scheinecker, Giorgio Fabris, Devashish C Shah, et al. “Low-Noise
    Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures for Prototyping Hybrid
    Semiconducting–Superconducting Devices.” <i>Applied Physics Letters</i>. AIP Publishing,
    2026. <a href="https://doi.org/10.1063/5.0333142">https://doi.org/10.1063/5.0333142</a>.
  ieee: M. Borovkov <i>et al.</i>, “Low-noise quantum dots in ultra-shallow Ge/SiGe
    heterostructures for prototyping hybrid semiconducting–superconducting devices,”
    <i>Applied Physics Letters</i>, vol. 129, no. 3. AIP Publishing, 2026.
  ista: Borovkov M, Schell YA, Sokolova D, Roux KER, Falthansl-Scheinecker P, Fabris
    G, Shah DC, Saez Mollejo J, Previdi R, Taha I, Genç A, Arbiol J, Calcaterra S,
    Oliveira ADC, Chrastina D, Isella G, Bubis A, Katsaros G. 2026. Low-noise quantum
    dots in ultra-shallow Ge/SiGe heterostructures for prototyping hybrid semiconducting–superconducting
    devices. Applied Physics Letters. 129(3), 033505.
  mla: Borovkov, Maksim, et al. “Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures
    for Prototyping Hybrid Semiconducting–Superconducting Devices.” <i>Applied Physics
    Letters</i>, vol. 129, no. 3, 033505, AIP Publishing, 2026, doi:<a href="https://doi.org/10.1063/5.0333142">10.1063/5.0333142</a>.
  short: M. Borovkov, Y.A. Schell, D. Sokolova, K.E.R. Roux, P. Falthansl-Scheinecker,
    G. Fabris, D.C. Shah, J. Saez Mollejo, R. Previdi, I. Taha, A. Genç, J. Arbiol,
    S. Calcaterra, A.D.C. Oliveira, D. Chrastina, G. Isella, A. Bubis, G. Katsaros,
    Applied Physics Letters 129 (2026).
corr_author: '1'
das_tickbox: '1'
dataavailabilitystatement: The data that support the findings of this study are openly
  available in Institute of Science and Technology repository at http://doi.org/10.15479/AT-ISTA-22242,
  Ref. 50.
date_created: 2026-08-02T22:01:53Z
date_published: 2026-07-20T00:00:00Z
date_updated: 2026-08-03T11:08:39Z
day: '20'
department:
- _id: GeKa
- _id: GradSch
- _id: NanoFab
doi: 10.1063/5.0333142
external_id:
  arxiv:
  - '2602.21363'
fulldoi: https://doi.org/10.1063/5.0333142
intvolume: '       129'
issue: '3'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.48550/arXiv.2602.21363
month: '07'
oa: 1
oa_version: Preprint
project:
- _id: bdc2ca30-d553-11ed-ba76-cf164a5bb811
  grant_number: '101115315'
  name: Quantum bits with Kitaev Transmons
- _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: 5b9e579c-ab3d-11f0-914f-88754c5b5a3f
  grant_number: PAT 7682124
  name: Superconducting spin qubits in planar Ge
- _id: bd8bd29e-d553-11ed-ba76-f0070d4b237a
  grant_number: P36507
  name: Merging spin and superconducting qubits in planar Ge
- _id: 8ea8abf7-16d5-11f0-9cad-c41e56ec8bb3
  grant_number: '101150858'
  name: Realization and Manipulation of a Planar hybrid superconducting Andreev spin
    qubit in Germanium
publication: Applied Physics Letters
publication_identifier:
  eissn:
  - 1077-3118
  issn:
  - 0003-6951
publication_status: published
publisher: AIP Publishing
quality_controlled: '1'
related_material:
  record:
  - id: '22242'
    relation: research_data
    status: public
researchdata_availability: yes
scopus_import: '1'
status: public
supplementarymaterial: yes
title: Low-noise quantum dots in ultra-shallow Ge/SiGe heterostructures for prototyping
  hybrid semiconducting–superconducting devices
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 129
year: '2026'
...
---
OA_place: repository
_id: '22242'
abstract:
- lang: eng
  text: This deposit contains the data and analysis code accompanying the publication
    "Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures for Prototyping
    Hybrid Semiconducting–Superconducting Devices" (Borovkov et al.). The deposit
    includes the raw transport and current-noise measurements of three gate-defined
    quantum-dot devices as QCodes SQLite databases, the master table of the charge-noise
    (flank-method) analysis with the pointers linking every analyzed PSD trace to
    the raw data, the toy-model noise simulation datasets behind the supplementary
    figures, the archived analysis figures (PSD fits and lever-arm extractions), and
    the Python code reproducing the full analysis and all figures. The code is also
    maintained at https://github.com/ISTA-Nanoelectronics/noise_paper_public; instructions
    are provided in the README files.
acknowledged_ssus:
- _id: M-Shop
- _id: NanoFab
article_processing_charge: No
author:
- first_name: Maksim
  full_name: Borovkov, Maksim
  id: 1fd0975f-8b61-11ed-b69e-d149334f28c5
  last_name: Borovkov
citation:
  ama: Borovkov M. Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures
    for Prototyping Hybrid Semiconducting-Superconducting Devices. 2026. doi:<a href="https://doi.org/10.15479/AT-ISTA-22242">10.15479/AT-ISTA-22242</a>
  apa: Borovkov, M. (2026). Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures
    for Prototyping Hybrid Semiconducting-Superconducting Devices. Institute of Science
    and Technology Austria. <a href="https://doi.org/10.15479/AT-ISTA-22242">https://doi.org/10.15479/AT-ISTA-22242</a>
  chicago: Borovkov, Maksim. “Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures
    for Prototyping Hybrid Semiconducting-Superconducting Devices.” Institute of Science
    and Technology Austria, 2026. <a href="https://doi.org/10.15479/AT-ISTA-22242">https://doi.org/10.15479/AT-ISTA-22242</a>.
  ieee: M. Borovkov, “Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures
    for Prototyping Hybrid Semiconducting-Superconducting Devices.” Institute of Science
    and Technology Austria, 2026.
  ista: Borovkov M. 2026. Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures
    for Prototyping Hybrid Semiconducting-Superconducting Devices, Institute of Science
    and Technology Austria, <a href="https://doi.org/10.15479/AT-ISTA-22242">10.15479/AT-ISTA-22242</a>.
  mla: Borovkov, Maksim. <i>Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures
    for Prototyping Hybrid Semiconducting-Superconducting Devices</i>. Institute of
    Science and Technology Austria, 2026, doi:<a href="https://doi.org/10.15479/AT-ISTA-22242">10.15479/AT-ISTA-22242</a>.
  short: M. Borovkov, (2026).
contributor:
- contributor_type: contact_person
  first_name: Maksim
  id: 1fd0975f-8b61-11ed-b69e-d149334f28c5
  last_name: Borovkov
corr_author: '1'
date_created: 2026-07-04T17:32:27Z
date_published: 2026-07-04T00:00:00Z
date_updated: 2026-08-03T11:08:38Z
day: '04'
ddc:
- '530'
department:
- _id: GradSch
- _id: GeKa
doi: 10.15479/AT-ISTA-22242
doi_confirm: '1'
file:
- access_level: open_access
  checksum: 2a1ea297e01a7a202a6b144d69a46eef
  content_type: application/x-zip-compressed
  creator: mborovko
  date_created: 2026-07-04T17:28:49Z
  date_updated: 2026-07-04T17:28:49Z
  file_id: '22243'
  file_name: noise_paper_public_deposit.zip
  file_size: 3082596099
  relation: main_file
  success: 1
file_date_updated: 2026-07-04T17:28:49Z
fulldoi: https://doi.org/10.15479/AT-ISTA-22242
has_accepted_license: '1'
license: https://creativecommons.org/licenses/by/4.0/
month: '07'
oa: 1
oa_version: Published Version
project:
- _id: bdc2ca30-d553-11ed-ba76-cf164a5bb811
  grant_number: '101115315'
  name: Quantum bits with Kitaev Transmons
- _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: bd8bd29e-d553-11ed-ba76-f0070d4b237a
  grant_number: P36507
  name: Merging spin and superconducting qubits in planar Ge
- _id: 8ea8abf7-16d5-11f0-9cad-c41e56ec8bb3
  grant_number: '101150858'
  name: Realization and Manipulation of a Planar hybrid superconducting Andreev spin
    qubit in Germanium
- _id: 5b9e579c-ab3d-11f0-914f-88754c5b5a3f
  grant_number: PAT 7682124
  name: Superconducting spin qubits in planar Ge
publisher: Institute of Science and Technology Austria
related_material:
  link:
  - relation: research_data
    url: https://github.com/ISTA-Nanoelectronics/noise_paper_public
  record:
  - id: '22619'
    relation: used_in_publication
    status: public
status: public
title: Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures for Prototyping
  Hybrid Semiconducting-Superconducting Devices
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: research_data
user_id: 68b8ca59-c5b3-11ee-8790-cd641c68093d
year: '2026'
...
---
OA_place: repository
OA_type: green
_id: '23156'
abstract:
- lang: eng
  text: "Extracting the current-phase relationship (CPR) of a single superconducting
    junction is challenging in practice and traditionally involves embedding the junction
    in a larger superconducting circuit containing SQUIDs and/or resonators. Applying
    ac driving to the junction has proven to be a viable and less invasive way to
    extract information about the few lowest harmonics of the CPR, by locating the
    integer and fractional Shapiro steps in the \U0001D43C⁢\U0001D449-curve of the
    driven junction. Here, we present an alternative driving-based method that allows
    to extract the full harmonic content of a CPR in a relatively noninvasive way,
    by fitting the measured critical currents of the driven junction as a function
    of driving power. We test our method, both using numerical simulations and in
    experiments, and we show that it works accurately."
acknowledgement: 'The authors thank Afonso Oliveira, Stefano Calcaterra, Daniel Chrastina,
  and Giovanni Isella for providing the Ge/SiGe heterostructure. This work was supported
  by the Research Council of Norway through its Centers of Excellence funding scheme,
  Project No. 262633, “QuSpin,” the FWF Project with DOI:10.55776/PAT7682124, OeAD
  “ISTA Austria: ISTernship Summer Programme, Non-EU countries” (Ref. No.: MPC-2025-00945),
  the Spanish Comunidad de Madrid (CM) “Talento Program” (Project No. 2022-T1/IND-24070),
  and the Spanish Ministry of Science, Innovation, and Universities through Grants
  No. CEX2024-001445-S (Severo Ochoa Centres of Excellence program) and No. PID2022-140552NA-I00,
  funded by MCIN/AEI/10.13039/501100011033.'
article_number: '044017'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Maxim
  full_name: Tjøtta, Maxim
  last_name: Tjøtta
- first_name: Devashish C
  full_name: Shah, Devashish C
  id: de191434-4e7e-11ef-bf4b-9a056fc19fc3
  last_name: Shah
  orcid: 0009-0007-5829-7707
- first_name: Kanishk
  full_name: Modi, Kanishk
  id: f05345fd-900f-11f1-bfd8-8c0b6eadcc7f
  last_name: Modi
- first_name: Marco
  full_name: Valentini, Marco
  id: C0BB2FAC-D767-11E9-B658-BC13E6697425
  last_name: Valentini
- first_name: Rubén
  full_name: Seoane Souto, Rubén
  last_name: Seoane Souto
- first_name: Georgios
  full_name: Katsaros, Georgios
  id: 38DB5788-F248-11E8-B48F-1D18A9856A87
  last_name: Katsaros
  orcid: 0000-0001-8342-202X
- first_name: Jeroen
  full_name: Danon, Jeroen
  last_name: Danon
citation:
  ama: Tjøtta M, Shah DC, Modi K, et al. Fast-driving spectroscopy of current-phase
    relationships of individual Josephson elements. <i>Physical Review Applied</i>.
    2026;26(4). doi:<a href="https://doi.org/10.1103/d3gl-qntm">10.1103/d3gl-qntm</a>
  apa: Tjøtta, M., Shah, D. C., Modi, K., Valentini, M., Seoane Souto, R., Katsaros,
    G., &#38; Danon, J. (2026). Fast-driving spectroscopy of current-phase relationships
    of individual Josephson elements. <i>Physical Review Applied</i>. American Physical
    Society. <a href="https://doi.org/10.1103/d3gl-qntm">https://doi.org/10.1103/d3gl-qntm</a>
  chicago: Tjøtta, Maxim, Devashish C Shah, Kanishk Modi, Marco Valentini, Rubén Seoane
    Souto, Georgios Katsaros, and Jeroen Danon. “Fast-Driving Spectroscopy of Current-Phase
    Relationships of Individual Josephson Elements.” <i>Physical Review Applied</i>.
    American Physical Society, 2026. <a href="https://doi.org/10.1103/d3gl-qntm">https://doi.org/10.1103/d3gl-qntm</a>.
  ieee: M. Tjøtta <i>et al.</i>, “Fast-driving spectroscopy of current-phase relationships
    of individual Josephson elements,” <i>Physical Review Applied</i>, vol. 26, no.
    4. American Physical Society, 2026.
  ista: Tjøtta M, Shah DC, Modi K, Valentini M, Seoane Souto R, Katsaros G, Danon
    J. 2026. Fast-driving spectroscopy of current-phase relationships of individual
    Josephson elements. Physical Review Applied. 26(4), 044017.
  mla: Tjøtta, Maxim, et al. “Fast-Driving Spectroscopy of Current-Phase Relationships
    of Individual Josephson Elements.” <i>Physical Review Applied</i>, vol. 26, no.
    4, 044017, American Physical Society, 2026, doi:<a href="https://doi.org/10.1103/d3gl-qntm">10.1103/d3gl-qntm</a>.
  short: M. Tjøtta, D.C. Shah, K. Modi, M. Valentini, R. Seoane Souto, G. Katsaros,
    J. Danon, Physical Review Applied 26 (2026).
das_tickbox: '1'
dataavailabilitystatement: The data that support the findings of this article are
  openly available at [10.5281/zenodo.22646275].
date_created: 2026-10-18T22:01:52Z
date_published: 2026-10-01T00:00:00Z
date_updated: 2026-10-19T07:25:01Z
day: '01'
department:
- _id: GeKa
- _id: GradSch
doi: 10.1103/d3gl-qntm
external_id:
  arxiv:
  - '2511.14313'
fulldoi: https://doi.org/10.1103/d3gl-qntm
intvolume: '        26'
issue: '4'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.48550/arXiv.2511.14313
month: '10'
oa: 1
oa_version: Preprint
project:
- _id: 5b9e579c-ab3d-11f0-914f-88754c5b5a3f
  grant_number: PAT 7682124
  name: Superconducting spin qubits in planar Ge
publication: Physical Review Applied
publication_identifier:
  eissn:
  - 2331-7019
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
researchdata_availability: yes
scopus_import: '1'
status: public
supplementarymaterial: yes
title: Fast-driving spectroscopy of current-phase relationships of individual Josephson
  elements
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 26
year: '2026'
...