---
OA_place: publisher
_id: '18129'
abstract:
- lang: eng
text: "State-of-the-art quantum computers, with roughly a thousand qubits, face
a crucial technological challenge of scaling up. Spins confined in quantum dots
(QDs) are a promising candidate\r\nfor qubits due to their long coherence, tunability,
control, and readout. However, their natural\r\ncoupling is the short-ranged (∼
100 nm) exchange interaction, limited to nearest neighbours.\r\nLong-ranged (∼
1 mm) qubit interactions mediated by a photon could be engineered through a\r\ncoherent
spin-photon coupling. Achieving a strong coupling to a photon is inherently challenging
in QDs due to the small dipole moment of the confined charge. However, the potential
of\r\nhigh-impedance resonators to compensate for this has gained significant
attention in the past\r\ndecade. Nevertheless, previous QD circuit quantum electrodynamics
implementations have not\r\nexceeded the impedance of ∼ 3.8 kΩ, leaving opportunities
for significant improvement. The\r\nlarge kinetic inductance of granular aluminium
(grAl) could provide an order-of-magnitude\r\nenhancement. However, fully exploiting
the potential of disordered or granular superconductors\r\nis challenging as their
impedances close to the superconductor-to-insulator transition are\r\ndifficult
to control reproducibly. We report on the realization of a wireless ohmmeter which\r\nallows
in situ resistance measurements during film deposition and, therefore, indirect
control\r\nof the kinetic inductance of grAl films. This allows us to reproducibly
fabricate resonators\r\nwith characteristic impedance exceeding the resistance
quantum, even reaching 22.3 kW, due\r\nto the large sheet kinetic inductance of
up to 3 nH □−1\r\n. By integrating an 8 kW resonator\r\nwith a germanium double
QD, we demonstrate a strong charge-photon coupling with the\r\nhighest rate reported,
566 MHz. The demonstrated method and grAl properties make these\r\nresonators
suitable for boosting the spin-photon coupling strength, a crucial requirement
for\r\nfast, high-fidelity, long-distance two-qubit gates.\r\n"
acknowledged_ssus:
- _id: M-Shop
- _id: NanoFab
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Marian
full_name: Janik, Marian
id: 396A1950-F248-11E8-B48F-1D18A9856A87
last_name: Janik
orcid: 0009-0003-9037-8831
citation:
ama: Janik M. Strong charge-photon coupling in Germanium enabled by granular aluminium
superinductors. 2024. doi:10.15479/at:ista:18129
apa: Janik, M. (2024). Strong charge-photon coupling in Germanium enabled by
granular aluminium superinductors. Institute of Science and Technology Austria.
https://doi.org/10.15479/at:ista:18129
chicago: Janik, Marian. “Strong Charge-Photon Coupling in Germanium Enabled by Granular
Aluminium Superinductors.” Institute of Science and Technology Austria, 2024.
https://doi.org/10.15479/at:ista:18129.
ieee: M. Janik, “Strong charge-photon coupling in Germanium enabled by granular
aluminium superinductors,” Institute of Science and Technology Austria, 2024.
ista: Janik M. 2024. Strong charge-photon coupling in Germanium enabled by granular
aluminium superinductors. Institute of Science and Technology Austria.
mla: Janik, Marian. Strong Charge-Photon Coupling in Germanium Enabled by Granular
Aluminium Superinductors. Institute of Science and Technology Austria, 2024,
doi:10.15479/at:ista:18129.
short: M. Janik, Strong Charge-Photon Coupling in Germanium Enabled by Granular
Aluminium Superinductors, Institute of Science and Technology Austria, 2024.
corr_author: '1'
date_created: 2024-09-23T17:25:43Z
date_published: 2024-09-24T00:00:00Z
date_updated: 2026-06-03T07:16:03Z
day: '24'
ddc:
- '539'
degree_awarded: PhD
department:
- _id: GradSch
- _id: GeKa
doi: 10.15479/at:ista:18129
file:
- access_level: closed
checksum: dc15958f6400b5bdaa28bf58fc7a4056
content_type: application/x-zip-compressed
creator: mjanik
date_created: 2024-09-23T17:15:09Z
date_updated: 2025-05-23T22:30:09Z
embargo_to: open_access
file_id: '18130'
file_name: janik_thesis.zip
file_size: 156207943
relation: source_file
- access_level: open_access
checksum: 74737aee285dc1f491643327350efe9c
content_type: application/pdf
creator: mjanik
date_created: 2024-09-23T17:15:30Z
date_updated: 2025-05-23T22:30:09Z
embargo: 2025-05-23
file_id: '18131'
file_name: janik_thesis_pdfa.pdf
file_size: 96195684
relation: main_file
file_date_updated: 2025-05-23T22:30:09Z
has_accepted_license: '1'
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: '164'
project:
- _id: c0977eea-5a5b-11eb-8a69-a862db0cf4d1
grant_number: I05060
name: High impedance circuit quantum electrodynamics with hole spins
- _id: bd8bd29e-d553-11ed-ba76-f0070d4b237a
grant_number: P36507
name: Merging spin and superconducting qubits in planar Ge
- _id: 237B3DA4-32DE-11EA-91FC-C7463DDC885E
call_identifier: FWF
grant_number: P32235
name: Towards scalable hut wire quantum devices
- _id: 34c0acea-11ca-11ed-8bc3-8775e10fd452
grant_number: '101069515'
name: Integrated Germanium Quantum Technology
- _id: eb9b30ac-77a9-11ec-83b8-871f581d53d2
name: Protected states of quantum matter
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '18144'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Georgios
full_name: Katsaros, Georgios
id: 38DB5788-F248-11E8-B48F-1D18A9856A87
last_name: Katsaros
orcid: 0000-0001-8342-202X
title: Strong charge-photon coupling in Germanium enabled by granular aluminium superinductors
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: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2024'
...