---
_id: '13175'
abstract:
- lang: eng
  text: "About a 100 years ago, we discovered that our universe is inherently noisy,
    that is, measuring any physical quantity with a precision beyond a certain point
    is not possible because of an omnipresent inherent noise. We call this - the quantum
    noise. Certain physical processes allow this quantum noise to get correlated in
    conjugate physical variables. These quantum correlations can be used to go beyond
    the potential of our inherently noisy universe and obtain a quantum advantage
    over the classical applications. \r\n\r\nQuantum noise being inherent also means
    that, at the fundamental level, the physical quantities are not well defined and
    therefore, objects can stay in multiple states at the same time. For example,
    the position of a particle not being well defined means that the particle is in
    multiple positions at the same time. About 4 decades ago, we started exploring
    the possibility of using objects which can be in multiple states at the same time
    to increase the dimensionality in computation. Thus, the field of quantum computing
    was born. We discovered that using quantum entanglement, a property closely related
    to quantum correlations, can be used to speed up computation of certain problems,
    such as factorisation of large numbers, faster than any known classical algorithm.
    Thus began the pursuit to make quantum computers a reality. \r\n\r\nTill date,
    we have explored quantum control over many physical systems including photons,
    spins, atoms, ions and even simple circuits made up of superconducting material.
    However, there persists one ubiquitous theme. The more readily a system interacts
    with an external field or matter, the more easily we can control it. But this
    also means that such a system can easily interact with a noisy environment and
    quickly lose its coherence. Consequently, such systems like electron spins need
    to be protected from the environment to ensure the longevity of their coherence.
    Other systems like nuclear spins are naturally protected as they do not interact
    easily with the environment. But, due to the same reason, it is harder to interact
    with such systems. \r\n\r\nAfter decades of experimentation with various systems,
    we are convinced that no one type of quantum system would be the best for all
    the quantum applications. We would need hybrid systems which are all interconnected
    - much like the current internet where all sorts of devices can all talk to each
    other - but now for quantum devices. A quantum internet. \r\n\r\nOptical photons
    are the best contenders to carry information for the quantum internet. They can
    carry quantum information cheaply and without much loss - the same reasons which
    has made them the backbone of our current internet. Following this direction,
    many systems, like trapped ions, have already demonstrated successful quantum
    links over a large distances using optical photons. However, some of the most
    promising contenders for quantum computing which are based on microwave frequencies
    have been left behind. This is because high energy optical photons can adversely
    affect fragile low-energy microwave systems. \r\n\r\nIn this thesis, we present
    substantial progress on this missing quantum link between microwave and optics
    using electrooptical nonlinearities in lithium niobate. The nonlinearities are
    enhanced by using resonant cavities for all the involved modes leading to observation
    of strong direct coupling between optical and microwave frequencies. With this
    strong coupling we are not only able to achieve almost 100\\% internal conversion
    efficiency with low added noise, thus presenting a quantum-enabled transducer,
    but also we are able to observe novel effects such as cooling of a microwave mode
    using optics. The strong coupling regime also leads to direct observation of dynamical
    backaction effect between microwave and optical frequencies which are studied
    in detail here. Finally, we also report first observation of microwave-optics
    entanglement in form of two-mode squeezed vacuum squeezed 0.7dB below vacuum level.
    \r\nWith this new bridge between microwave and optics, the microwave-based quantum
    technologies can finally be a part of a quantum network which is based on optical
    photons - putting us one step closer to a future with quantum internet. "
acknowledged_ssus:
- _id: M-Shop
- _id: SSU
- _id: NanoFab
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Rishabh
  full_name: Sahu, Rishabh
  id: 47D26E34-F248-11E8-B48F-1D18A9856A87
  last_name: Sahu
  orcid: 0000-0001-6264-2162
citation:
  ama: Sahu R. Cavity quantum electrooptics. 2023. doi:<a href="https://doi.org/10.15479/at:ista:13175">10.15479/at:ista:13175</a>
  apa: Sahu, R. (2023). <i>Cavity quantum electrooptics</i>. Institute of Science
    and Technology Austria. <a href="https://doi.org/10.15479/at:ista:13175">https://doi.org/10.15479/at:ista:13175</a>
  chicago: Sahu, Rishabh. “Cavity Quantum Electrooptics.” Institute of Science and
    Technology Austria, 2023. <a href="https://doi.org/10.15479/at:ista:13175">https://doi.org/10.15479/at:ista:13175</a>.
  ieee: R. Sahu, “Cavity quantum electrooptics,” Institute of Science and Technology
    Austria, 2023.
  ista: Sahu R. 2023. Cavity quantum electrooptics. Institute of Science and Technology
    Austria.
  mla: Sahu, Rishabh. <i>Cavity Quantum Electrooptics</i>. Institute of Science and
    Technology Austria, 2023, doi:<a href="https://doi.org/10.15479/at:ista:13175">10.15479/at:ista:13175</a>.
  short: R. Sahu, Cavity Quantum Electrooptics, Institute of Science and Technology
    Austria, 2023.
date_created: 2023-06-30T08:07:43Z
date_published: 2023-05-05T00:00:00Z
date_updated: 2024-10-29T09:11:06Z
day: '05'
ddc:
- '537'
- '535'
- '539'
degree_awarded: PhD
department:
- _id: GradSch
- _id: JoFi
doi: 10.15479/at:ista:13175
ec_funded: 1
file:
- access_level: open_access
  checksum: 7d03f1a5a5258ee43dfc3323dea4e08f
  content_type: application/pdf
  creator: cchlebak
  date_created: 2023-06-30T08:17:25Z
  date_updated: 2023-06-30T08:17:25Z
  file_id: '13176'
  file_name: thesis_pdfa.pdf
  file_size: 18688376
  relation: main_file
  success: 1
- access_level: closed
  checksum: c3b45317ae58e0527533f98c202d81b7
  content_type: application/x-zip-compressed
  creator: cchlebak
  date_created: 2023-07-06T11:35:15Z
  date_updated: 2023-07-06T11:35:15Z
  file_id: '13196'
  file_name: thesis.zip
  file_size: 37847025
  relation: source_file
file_date_updated: 2023-07-06T11:35:15Z
has_accepted_license: '1'
keyword:
- quantum optics
- electrooptics
- quantum networks
- quantum communication
- transduction
language:
- iso: eng
license: https://creativecommons.org/licenses/by-nc-sa/4.0/
month: '05'
oa: 1
oa_version: Published Version
page: '202'
project:
- _id: 26336814-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '758053'
  name: A Fiber Optic Transceiver for Superconducting Qubits
- _id: 9B868D20-BA93-11EA-9121-9846C619BF3A
  call_identifier: H2020
  grant_number: '899354'
  name: Quantum Local Area Networks with Superconducting Qubits
- _id: bdb108fd-d553-11ed-ba76-83dc74a9864f
  name: QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration
    of Superconducting Quantum Circuits
publication_identifier:
  isbn:
  - 978-3-99078-030-5
  issn:
  - 2663 - 337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
  record:
  - id: '12900'
    relation: old_edition
    status: public
  - id: '9114'
    relation: part_of_dissertation
    status: public
  - id: '10924'
    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: Cavity quantum electrooptics
tmp:
  image: /images/cc_by_nc_sa.png
  legal_code_url: https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode
  name: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC
    BY-NC-SA 4.0)
  short: CC BY-NC-SA (4.0)
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
---
_id: '13200'
abstract:
- lang: eng
  text: Recent quantum technologies have established precise quantum control of various
    microscopic systems using electromagnetic waves. Interfaces based on cryogenic
    cavity electro-optic systems are particularly promising, due to the direct interaction
    between microwave and optical fields in the quantum regime. Quantum optical control
    of superconducting microwave circuits has been precluded so far due to the weak
    electro-optical coupling as well as quasi-particles induced by the pump laser.
    Here we report the coherent control of a superconducting microwave cavity using
    laser pulses in a multimode electro-optical device at millikelvin temperature
    with near-unity cooperativity. Both the stationary and instantaneous responses
    of the microwave and optical modes comply with the coherent electro-optical interaction,
    and reveal only minuscule amount of excess back-action with an unanticipated time
    delay. Our demonstration enables wide ranges of applications beyond quantum transductions,
    from squeezing and quantum non-demolition measurements of microwave fields, to
    entanglement generation and hybrid quantum networks.
acknowledgement: This work was supported by the European Research Council under grant
  agreement no. 758053 (ERC StG QUNNECT), the European Union’s Horizon 2020 research
  and innovation program under grant agreement no. 899354 (FETopen SuperQuLAN), and
  the Austrian Science Fund (FWF) through BeyondC (F7105). L.Q. acknowledges generous
  support from the ISTFELLOW programme. W.H. is the recipient of an ISTplus postdoctoral
  fellowship with funding from the European Union’s Horizon 2020 research and innovation
  program under the Marie Skłodowska-Curie grant agreement no. 754411. G.A. is the
  recipient of a DOC fellowship of the Austrian Academy of Sciences at IST Austria.
article_number: '3784'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Liu
  full_name: Qiu, Liu
  id: 45e99c0d-1eb1-11eb-9b96-ed8ab2983cac
  last_name: Qiu
  orcid: 0000-0003-4345-4267
- first_name: Rishabh
  full_name: Sahu, Rishabh
  id: 47D26E34-F248-11E8-B48F-1D18A9856A87
  last_name: Sahu
  orcid: 0000-0001-6264-2162
- first_name: William J
  full_name: Hease, William J
  id: 29705398-F248-11E8-B48F-1D18A9856A87
  last_name: Hease
  orcid: 0000-0001-9868-2166
- first_name: Georg M
  full_name: Arnold, Georg M
  id: 3770C838-F248-11E8-B48F-1D18A9856A87
  last_name: Arnold
  orcid: 0000-0003-1397-7876
- first_name: Johannes M
  full_name: Fink, Johannes M
  id: 4B591CBA-F248-11E8-B48F-1D18A9856A87
  last_name: Fink
  orcid: 0000-0001-8112-028X
citation:
  ama: Qiu L, Sahu R, Hease WJ, Arnold GM, Fink JM. Coherent optical control of a
    superconducting microwave cavity via electro-optical dynamical back-action. <i>Nature
    Communications</i>. 2023;14. doi:<a href="https://doi.org/10.1038/s41467-023-39493-3">10.1038/s41467-023-39493-3</a>
  apa: Qiu, L., Sahu, R., Hease, W. J., Arnold, G. M., &#38; Fink, J. M. (2023). Coherent
    optical control of a superconducting microwave cavity via electro-optical dynamical
    back-action. <i>Nature Communications</i>. Nature Research. <a href="https://doi.org/10.1038/s41467-023-39493-3">https://doi.org/10.1038/s41467-023-39493-3</a>
  chicago: Qiu, Liu, Rishabh Sahu, William J Hease, Georg M Arnold, and Johannes M
    Fink. “Coherent Optical Control of a Superconducting Microwave Cavity via Electro-Optical
    Dynamical Back-Action.” <i>Nature Communications</i>. Nature Research, 2023. <a
    href="https://doi.org/10.1038/s41467-023-39493-3">https://doi.org/10.1038/s41467-023-39493-3</a>.
  ieee: L. Qiu, R. Sahu, W. J. Hease, G. M. Arnold, and J. M. Fink, “Coherent optical
    control of a superconducting microwave cavity via electro-optical dynamical back-action,”
    <i>Nature Communications</i>, vol. 14. Nature Research, 2023.
  ista: Qiu L, Sahu R, Hease WJ, Arnold GM, Fink JM. 2023. Coherent optical control
    of a superconducting microwave cavity via electro-optical dynamical back-action.
    Nature Communications. 14, 3784.
  mla: Qiu, Liu, et al. “Coherent Optical Control of a Superconducting Microwave Cavity
    via Electro-Optical Dynamical Back-Action.” <i>Nature Communications</i>, vol.
    14, 3784, Nature Research, 2023, doi:<a href="https://doi.org/10.1038/s41467-023-39493-3">10.1038/s41467-023-39493-3</a>.
  short: L. Qiu, R. Sahu, W.J. Hease, G.M. Arnold, J.M. Fink, Nature Communications
    14 (2023).
date_created: 2023-07-09T22:01:11Z
date_published: 2023-06-24T00:00:00Z
date_updated: 2024-08-07T07:11:55Z
day: '24'
ddc:
- '000'
department:
- _id: JoFi
doi: 10.1038/s41467-023-39493-3
ec_funded: 1
external_id:
  arxiv:
  - '2210.12443'
  isi:
  - '001018100800002'
  pmid:
  - '37355691'
file:
- access_level: open_access
  checksum: ec7ccd2c08f90d59cab302fd0d7776a4
  content_type: application/pdf
  creator: alisjak
  date_created: 2023-07-10T10:10:54Z
  date_updated: 2023-07-10T10:10:54Z
  file_id: '13206'
  file_name: 2023_NatureComms_Qiu.pdf
  file_size: 1349134
  relation: main_file
  success: 1
file_date_updated: 2023-07-10T10:10:54Z
has_accepted_license: '1'
intvolume: '        14'
isi: 1
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
pmid: 1
project:
- _id: 26336814-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '758053'
  name: A Fiber Optic Transceiver for Superconducting Qubits
- _id: 9B868D20-BA93-11EA-9121-9846C619BF3A
  call_identifier: H2020
  grant_number: '899354'
  name: Quantum Local Area Networks with Superconducting Qubits
- _id: bdb108fd-d553-11ed-ba76-83dc74a9864f
  name: QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration
    of Superconducting Quantum Circuits
- _id: 260C2330-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '754411'
  name: ISTplus - Postdoctoral Fellowships
- _id: 25681D80-B435-11E9-9278-68D0E5697425
  call_identifier: FP7
  grant_number: '291734'
  name: International IST Postdoc Fellowship Programme
- _id: 2671EB66-B435-11E9-9278-68D0E5697425
  name: Coherent on-chip conversion of superconducting qubit signals from microwaves
    to optical frequencies
publication: Nature Communications
publication_identifier:
  eissn:
  - 2041-1723
publication_status: published
publisher: Nature Research
quality_controlled: '1'
scopus_import: '1'
status: public
title: Coherent optical control of a superconducting microwave cavity via electro-optical
  dynamical back-action
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: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 14
year: '2023'
...
---
_id: '12900'
abstract:
- lang: eng
  text: "About a 100 years ago, we discovered that our universe is inherently noisy,
    that is, measuring any physical quantity with a precision beyond a certain point
    is not possible because of an omnipresent inherent noise. We call this - the quantum
    noise. Certain physical processes allow this quantum noise to get correlated in
    conjugate physical variables. These quantum correlations can be used to go beyond
    the potential of our inherently noisy universe and obtain a quantum advantage
    over the classical applications. \r\n\r\nQuantum noise being inherent also means
    that, at the fundamental level, the physical quantities are not well defined and
    therefore, objects can stay in multiple states at the same time. For example,
    the position of a particle not being well defined means that the particle is in
    multiple positions at the same time. About 4 decades ago, we started exploring
    the possibility of using objects which can be in multiple states at the same time
    to increase the dimensionality in computation. Thus, the field of quantum computing
    was born. We discovered that using quantum entanglement, a property closely related
    to quantum correlations, can be used to speed up computation of certain problems,
    such as factorisation of large numbers, faster than any known classical algorithm.
    Thus began the pursuit to make quantum computers a reality. \r\n\r\nTill date,
    we have explored quantum control over many physical systems including photons,
    spins, atoms, ions and even simple circuits made up of superconducting material.
    However, there persists one ubiquitous theme. The more readily a system interacts
    with an external field or matter, the more easily we can control it. But this
    also means that such a system can easily interact with a noisy environment and
    quickly lose its coherence. Consequently, such systems like electron spins need
    to be protected from the environment to ensure the longevity of their coherence.
    Other systems like nuclear spins are naturally protected as they do not interact
    easily with the environment. But, due to the same reason, it is harder to interact
    with such systems. \r\n\r\nAfter decades of experimentation with various systems,
    we are convinced that no one type of quantum system would be the best for all
    the quantum applications. We would need hybrid systems which are all interconnected
    - much like the current internet where all sorts of devices can all talk to each
    other - but now for quantum devices. A quantum internet. \r\n\r\nOptical photons
    are the best contenders to carry information for the quantum internet. They can
    carry quantum information cheaply and without much loss - the same reasons which
    has made them the backbone of our current internet. Following this direction,
    many systems, like trapped ions, have already demonstrated successful quantum
    links over a large distances using optical photons. However, some of the most
    promising contenders for quantum computing which are based on microwave frequencies
    have been left behind. This is because high energy optical photons can adversely
    affect fragile low-energy microwave systems. \r\n\r\nIn this thesis, we present
    substantial progress on this missing quantum link between microwave and optics
    using electrooptical nonlinearities in lithium niobate. The nonlinearities are
    enhanced by using resonant cavities for all the involved modes leading to observation
    of strong direct coupling between optical and microwave frequencies. With this
    strong coupling we are not only able to achieve almost 100\\% internal conversion
    efficiency with low added noise, thus presenting a quantum-enabled transducer,
    but also we are able to observe novel effects such as cooling of a microwave mode
    using optics. The strong coupling regime also leads to direct observation of dynamical
    backaction effect between microwave and optical frequencies which are studied
    in detail here. Finally, we also report first observation of microwave-optics
    entanglement in form of two-mode squeezed vacuum squeezed 0.7dB below vacuum level.
    \r\nWith this new bridge between microwave and optics, the microwave-based quantum
    technologies can finally be a part of a quantum network which is based on optical
    photons - putting us one step closer to a future with quantum internet. "
acknowledged_ssus:
- _id: M-Shop
- _id: SSU
- _id: NanoFab
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Rishabh
  full_name: Sahu, Rishabh
  id: 47D26E34-F248-11E8-B48F-1D18A9856A87
  last_name: Sahu
  orcid: 0000-0001-6264-2162
citation:
  ama: Sahu R. Cavity quantum electrooptics. 2023. doi:<a href="https://doi.org/10.15479/at:ista:12900">10.15479/at:ista:12900</a>
  apa: Sahu, R. (2023). <i>Cavity quantum electrooptics</i>. Institute of Science
    and Technology Austria. <a href="https://doi.org/10.15479/at:ista:12900">https://doi.org/10.15479/at:ista:12900</a>
  chicago: Sahu, Rishabh. “Cavity Quantum Electrooptics.” Institute of Science and
    Technology Austria, 2023. <a href="https://doi.org/10.15479/at:ista:12900">https://doi.org/10.15479/at:ista:12900</a>.
  ieee: R. Sahu, “Cavity quantum electrooptics,” Institute of Science and Technology
    Austria, 2023.
  ista: Sahu R. 2023. Cavity quantum electrooptics. Institute of Science and Technology
    Austria.
  mla: Sahu, Rishabh. <i>Cavity Quantum Electrooptics</i>. Institute of Science and
    Technology Austria, 2023, doi:<a href="https://doi.org/10.15479/at:ista:12900">10.15479/at:ista:12900</a>.
  short: R. Sahu, Cavity Quantum Electrooptics, Institute of Science and Technology
    Austria, 2023.
date_created: 2023-05-05T11:08:50Z
date_published: 2023-05-05T00:00:00Z
date_updated: 2024-10-29T09:11:05Z
day: '05'
ddc:
- '537'
- '535'
- '539'
degree_awarded: PhD
department:
- _id: GradSch
- _id: JoFi
doi: 10.15479/at:ista:12900
ec_funded: 1
file:
- access_level: closed
  checksum: 8cbdab9c37ee55e591092a6f66b272c4
  content_type: application/x-zip-compressed
  creator: rsahu
  date_created: 2023-05-09T08:45:14Z
  date_updated: 2023-06-06T22:30:03Z
  embargo_to: open_access
  file_id: '12928'
  file_name: thesis.zip
  file_size: 36767177
  relation: source_file
- access_level: closed
  checksum: 439659ead46618147309be39d9dd5a8c
  content_type: application/pdf
  creator: rsahu
  date_created: 2023-05-09T08:51:17Z
  date_updated: 2023-07-06T11:37:40Z
  file_id: '12929'
  file_name: thesis_pdfa_final.pdf
  file_size: 17501990
  relation: main_file
file_date_updated: 2023-07-06T11:37:40Z
has_accepted_license: '1'
keyword:
- quantum optics
- electrooptics
- quantum networks
- quantum communication
- transduction
language:
- iso: eng
month: '05'
oa_version: Published Version
page: '190'
project:
- _id: 26336814-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '758053'
  name: A Fiber Optic Transceiver for Superconducting Qubits
- _id: 9B868D20-BA93-11EA-9121-9846C619BF3A
  call_identifier: H2020
  grant_number: '899354'
  name: Quantum Local Area Networks with Superconducting Qubits
- _id: bdb108fd-d553-11ed-ba76-83dc74a9864f
  name: QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration
    of Superconducting Quantum Circuits
publication_identifier:
  isbn:
  - 978-3-99078-030-5
  issn:
  - 2663 - 337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
  record:
  - id: '9114'
    relation: part_of_dissertation
    status: public
  - id: '10924'
    relation: part_of_dissertation
    status: public
  - id: '13175'
    relation: new_edition
    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: Cavity quantum electrooptics
tmp:
  image: /images/cc_by_nc_sa.png
  legal_code_url: https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode
  name: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC
    BY-NC-SA 4.0)
  short: CC BY-NC-SA (4.0)
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2023'
...
