---
_id: '10058'
abstract:
- lang: eng
  text: 'Quantum information and computation has become a vast field paved with opportunities
    for researchers and investors. As large multinational companies and international
    funds are heavily investing in quantum technologies it is still a question which
    platform is best suited for the task of realizing a scalable quantum processor.
    In this work we investigate hole spins in Ge quantum wells. These hold great promise
    as they possess several favorable properties: a small effective mass, a strong
    spin-orbit coupling, long relaxation time and an inherent immunity to hyperfine
    noise. All these characteristics helped Ge hole spin qubits to evolve from a single
    qubit to a fully entangled four qubit processor in only 3 years. Here, we investigated
    a qubit approach leveraging the large out-of-plane g-factors of heavy hole states
    in Ge quantum dots. We found this qubit to be reproducibly operable at extremely
    low magnetic field and at large speeds while maintaining coherence. This was possible
    because large differences of g-factors in adjacent dots can be achieved in the
    out-of-plane direction. In the in-plane direction the small g-factors, on the
    other hand, can be altered very effectively by the confinement potentials. Here,
    we found that this can even lead to a sign change of the g-factors. The resulting
    g-factor difference alters the dynamics of the system drastically and produces
    effects typically attributed to a spin-orbit induced spin-flip term.  The investigations
    carried out in this thesis give further insights into the possibilities of holes
    in Ge and reveal new physical properties that need to be considered when designing
    future spin qubit experiments.'
acknowledged_ssus:
- _id: M-Shop
- _id: NanoFab
acknowledgement: The author gratefully acknowledges support by the Austrian Science
  Fund (FWF), grants No P30207, and the Nomis foundation.
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Daniel
  full_name: Jirovec, Daniel
  id: 4C473F58-F248-11E8-B48F-1D18A9856A87
  last_name: Jirovec
  orcid: 0000-0002-7197-4801
citation:
  ama: Jirovec D. Singlet-Triplet qubits and spin-orbit interaction in 2-dimensional
    Ge hole gases. 2021. doi:<a href="https://doi.org/10.15479/at:ista:10058">10.15479/at:ista:10058</a>
  apa: Jirovec, D. (2021). <i>Singlet-Triplet qubits and spin-orbit interaction in
    2-dimensional Ge hole gases</i>. Institute of Science and Technology Austria.
    <a href="https://doi.org/10.15479/at:ista:10058">https://doi.org/10.15479/at:ista:10058</a>
  chicago: Jirovec, Daniel. “Singlet-Triplet Qubits and Spin-Orbit Interaction in
    2-Dimensional Ge Hole Gases.” Institute of Science and Technology Austria, 2021.
    <a href="https://doi.org/10.15479/at:ista:10058">https://doi.org/10.15479/at:ista:10058</a>.
  ieee: D. Jirovec, “Singlet-Triplet qubits and spin-orbit interaction in 2-dimensional
    Ge hole gases,” Institute of Science and Technology Austria, 2021.
  ista: Jirovec D. 2021. Singlet-Triplet qubits and spin-orbit interaction in 2-dimensional
    Ge hole gases. Institute of Science and Technology Austria.
  mla: Jirovec, Daniel. <i>Singlet-Triplet Qubits and Spin-Orbit Interaction in 2-Dimensional
    Ge Hole Gases</i>. Institute of Science and Technology Austria, 2021, doi:<a href="https://doi.org/10.15479/at:ista:10058">10.15479/at:ista:10058</a>.
  short: D. Jirovec, Singlet-Triplet Qubits and Spin-Orbit Interaction in 2-Dimensional
    Ge Hole Gases, Institute of Science and Technology Austria, 2021.
date_created: 2021-09-30T07:53:49Z
date_published: 2021-10-05T00:00:00Z
date_updated: 2023-09-08T11:41:08Z
day: '05'
ddc:
- '621'
- '539'
degree_awarded: PhD
department:
- _id: GradSch
- _id: GeKa
doi: 10.15479/at:ista:10058
file:
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  date_created: 2021-09-30T14:29:14Z
  date_updated: 2022-12-20T23:30:07Z
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  file_size: 26910829
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file_date_updated: 2022-12-20T23:30:07Z
has_accepted_license: '1'
keyword:
- qubits
- quantum computing
- holes
language:
- iso: eng
month: '10'
oa: 1
oa_version: Published Version
page: '151'
project:
- _id: 2641CE5E-B435-11E9-9278-68D0E5697425
  call_identifier: FWF
  grant_number: P30207
  name: Hole spin orbit qubits in Ge quantum wells
publication_identifier:
  issn:
  - 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
  record:
  - id: '8831'
    relation: part_of_dissertation
    status: public
  - id: '10065'
    relation: part_of_dissertation
    status: public
  - id: '10066'
    relation: part_of_dissertation
    status: public
  - id: '8909'
    relation: part_of_dissertation
    status: public
  - id: '5816'
    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: Singlet-Triplet qubits and spin-orbit interaction in 2-dimensional Ge hole
  gases
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: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2021'
...
---
_id: '9920'
abstract:
- lang: eng
  text: 'This work is concerned with two fascinating circuit quantum electrodynamics
    components, the Josephson junction and the geometric superinductor, and the interesting
    experiments that can be done by combining the two. The Josephson junction has
    revolutionized the field of superconducting circuits as a non-linear dissipation-less
    circuit element and is used in almost all superconducting qubit implementations
    since the 90s. On the other hand, the superinductor is a relatively new circuit
    element introduced as a key component of the fluxonium qubit in 2009. This is
    an inductor with characteristic impedance larger than the resistance quantum and
    self-resonance frequency in the GHz regime. The combination of these two elements
    can occur in two fundamental ways: in parallel and in series. When connected in
    parallel the two create the fluxonium qubit, a loop with large inductance and
    a rich energy spectrum reliant on quantum tunneling. On the other hand placing
    the two elements in series aids with the measurement of the IV curve of a single
    Josephson junction in a high impedance environment. In this limit theory predicts
    that the junction will behave as its dual element: the phase-slip junction. While
    the Josephson junction acts as a non-linear inductor the phase-slip junction has
    the behavior of a non-linear capacitance and can be used to measure new Josephson
    junction phenomena, namely Coulomb blockade of Cooper pairs and phase-locked Bloch
    oscillations. The latter experiment allows for a direct link between frequency
    and current which is an elusive connection in quantum metrology. This work introduces
    the geometric superinductor, a superconducting circuit element where the high
    inductance is due to the geometry rather than the material properties of the superconductor,
    realized from a highly miniaturized superconducting planar coil. These structures
    will be described and characterized as resonators and qubit inductors and progress
    towards the measurement of phase-locked Bloch oscillations will be presented.'
acknowledged_ssus:
- _id: NanoFab
- _id: M-Shop
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Matilda
  full_name: Peruzzo, Matilda
  id: 3F920B30-F248-11E8-B48F-1D18A9856A87
  last_name: Peruzzo
  orcid: 0000-0002-3415-4628
citation:
  ama: Peruzzo M. Geometric superinductors and their applications in circuit quantum
    electrodynamics. 2021. doi:<a href="https://doi.org/10.15479/at:ista:9920">10.15479/at:ista:9920</a>
  apa: Peruzzo, M. (2021). <i>Geometric superinductors and their applications in circuit
    quantum electrodynamics</i>. Institute of Science and Technology Austria. <a href="https://doi.org/10.15479/at:ista:9920">https://doi.org/10.15479/at:ista:9920</a>
  chicago: Peruzzo, Matilda. “Geometric Superinductors and Their Applications in Circuit
    Quantum Electrodynamics.” Institute of Science and Technology Austria, 2021. <a
    href="https://doi.org/10.15479/at:ista:9920">https://doi.org/10.15479/at:ista:9920</a>.
  ieee: M. Peruzzo, “Geometric superinductors and their applications in circuit quantum
    electrodynamics,” Institute of Science and Technology Austria, 2021.
  ista: Peruzzo M. 2021. Geometric superinductors and their applications in circuit
    quantum electrodynamics. Institute of Science and Technology Austria.
  mla: Peruzzo, Matilda. <i>Geometric Superinductors and Their Applications in Circuit
    Quantum Electrodynamics</i>. Institute of Science and Technology Austria, 2021,
    doi:<a href="https://doi.org/10.15479/at:ista:9920">10.15479/at:ista:9920</a>.
  short: M. Peruzzo, Geometric Superinductors and Their Applications in Circuit Quantum
    Electrodynamics, Institute of Science and Technology Austria, 2021.
date_created: 2021-08-16T09:44:09Z
date_published: 2021-08-19T00:00:00Z
date_updated: 2024-09-10T12:23:56Z
day: '19'
ddc:
- '539'
degree_awarded: PhD
department:
- _id: GradSch
- _id: JoFi
doi: 10.15479/at:ista:9920
file:
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  checksum: 3cd1986efde5121d7581f6fcf9090da8
  content_type: application/x-zip-compressed
  creator: mperuzzo
  date_created: 2021-08-16T09:33:21Z
  date_updated: 2021-09-06T08:39:47Z
  file_id: '9924'
  file_name: GeometricSuperinductorsForCQED.zip
  file_size: 151387283
  relation: source_file
- access_level: open_access
  checksum: 50928c621cdf0775d7a5906b9dc8602c
  content_type: application/pdf
  creator: mperuzzo
  date_created: 2021-08-18T14:20:06Z
  date_updated: 2021-09-06T08:39:47Z
  file_id: '9939'
  file_name: GeometricSuperinductorsAndTheirApplicationsIncQED-1b.pdf
  file_size: 17596344
  relation: main_file
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  checksum: 37f486aa1b622fe44af00d627ec13f6c
  content_type: application/pdf
  creator: mperuzzo
  date_created: 2021-08-18T14:20:09Z
  date_updated: 2021-09-06T08:39:47Z
  description: Extra copy of the thesis as PDF/A-2b
  file_id: '9940'
  file_name: GeometricSuperinductorsAndTheirApplicationsIncQED-2b.pdf
  file_size: 17592425
  relation: other
file_date_updated: 2021-09-06T08:39:47Z
has_accepted_license: '1'
keyword:
- quantum computing
- superinductor
- quantum metrology
language:
- iso: eng
month: '08'
oa: 1
oa_version: Published Version
page: '149'
publication_identifier:
  isbn:
  - 978-3-99078-013-8
  issn:
  - 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
  record:
  - id: '9928'
    relation: part_of_dissertation
    status: public
  - id: '8755'
    relation: part_of_dissertation
    status: public
status: public
supervisor:
- first_name: Johannes M
  full_name: Fink, Johannes M
  id: 4B591CBA-F248-11E8-B48F-1D18A9856A87
  last_name: Fink
  orcid: 0000-0001-8112-028X
title: Geometric superinductors and their applications in circuit quantum electrodynamics
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2021'
...