---
_id: '45850'
abstract:
- lang: eng
  text: Interference between single photons is key for many quantum optics experiments
    and applications in quantum technologies, such as quantum communication or computation.
    It is advantageous to operate the systems at telecommunication wavelengths and
    to integrate the setups for these applications in order to improve stability,
    compactness and scalability. A new promising material platform for integrated
    quantum optics is lithium niobate on insulator (LNOI). Here, we realise Hong-Ou-Mandel
    (HOM) interference between telecom photons from an engineered parametric down-conversion
    source in an LNOI directional coupler. The coupler has been designed and fabricated
    in house and provides close to perfect balanced beam splitting. We obtain a raw
    HOM visibility of (93.5 ± 0.7) %, limited mainly by the source performance and
    in good agreement with off-chip measurements. This lays the foundation for more
    sophisticated quantum experiments in LNOI.
article_number: '23140'
author:
- first_name: Silia
  full_name: Babel, Silia
  id: '63231'
  last_name: Babel
  orcid: https://orcid.org/0000-0002-1568-2580
- first_name: Laura
  full_name: Bollmers, Laura
  id: '61375'
  last_name: Bollmers
- first_name: Marcello
  full_name: Massaro, Marcello
  id: '59545'
  last_name: Massaro
  orcid: 0000-0002-2539-7652
- first_name: Kai Hong
  full_name: Luo, Kai Hong
  id: '36389'
  last_name: Luo
  orcid: 0000-0003-1008-4976
- first_name: Michael
  full_name: Stefszky, Michael
  id: '42777'
  last_name: Stefszky
- first_name: Federico
  full_name: Pegoraro, Federico
  id: '88928'
  last_name: Pegoraro
- first_name: Philip
  full_name: Held, Philip
  id: '68236'
  last_name: Held
- first_name: Harald
  full_name: Herrmann, Harald
  id: '216'
  last_name: Herrmann
- first_name: Christof
  full_name: Eigner, Christof
  id: '13244'
  last_name: Eigner
  orcid: https://orcid.org/0000-0002-5693-3083
- first_name: Benjamin
  full_name: Brecht, Benjamin
  id: '27150'
  last_name: Brecht
  orcid: '0000-0003-4140-0556 '
- first_name: Laura
  full_name: Padberg, Laura
  id: '40300'
  last_name: Padberg
- first_name: Christine
  full_name: Silberhorn, Christine
  id: '26263'
  last_name: Silberhorn
citation:
  ama: Babel S, Bollmers L, Massaro M, et al. Demonstration of Hong-Ou-Mandel interference
    in an LNOI directional coupler. <i>Optics Express</i>. 2023;31(14). doi:<a href="https://doi.org/10.1364/oe.484126">10.1364/oe.484126</a>
  apa: Babel, S., Bollmers, L., Massaro, M., Luo, K. H., Stefszky, M., Pegoraro, F.,
    Held, P., Herrmann, H., Eigner, C., Brecht, B., Padberg, L., &#38; Silberhorn,
    C. (2023). Demonstration of Hong-Ou-Mandel interference in an LNOI directional
    coupler. <i>Optics Express</i>, <i>31</i>(14), Article 23140. <a href="https://doi.org/10.1364/oe.484126">https://doi.org/10.1364/oe.484126</a>
  bibtex: '@article{Babel_Bollmers_Massaro_Luo_Stefszky_Pegoraro_Held_Herrmann_Eigner_Brecht_et
    al._2023, title={Demonstration of Hong-Ou-Mandel interference in an LNOI directional
    coupler}, volume={31}, DOI={<a href="https://doi.org/10.1364/oe.484126">10.1364/oe.484126</a>},
    number={1423140}, journal={Optics Express}, publisher={Optica Publishing Group},
    author={Babel, Silia and Bollmers, Laura and Massaro, Marcello and Luo, Kai Hong
    and Stefszky, Michael and Pegoraro, Federico and Held, Philip and Herrmann, Harald
    and Eigner, Christof and Brecht, Benjamin and et al.}, year={2023} }'
  chicago: Babel, Silia, Laura Bollmers, Marcello Massaro, Kai Hong Luo, Michael Stefszky,
    Federico Pegoraro, Philip Held, et al. “Demonstration of Hong-Ou-Mandel Interference
    in an LNOI Directional Coupler.” <i>Optics Express</i> 31, no. 14 (2023). <a href="https://doi.org/10.1364/oe.484126">https://doi.org/10.1364/oe.484126</a>.
  ieee: 'S. Babel <i>et al.</i>, “Demonstration of Hong-Ou-Mandel interference in
    an LNOI directional coupler,” <i>Optics Express</i>, vol. 31, no. 14, Art. no.
    23140, 2023, doi: <a href="https://doi.org/10.1364/oe.484126">10.1364/oe.484126</a>.'
  mla: Babel, Silia, et al. “Demonstration of Hong-Ou-Mandel Interference in an LNOI
    Directional Coupler.” <i>Optics Express</i>, vol. 31, no. 14, 23140, Optica Publishing
    Group, 2023, doi:<a href="https://doi.org/10.1364/oe.484126">10.1364/oe.484126</a>.
  short: S. Babel, L. Bollmers, M. Massaro, K.H. Luo, M. Stefszky, F. Pegoraro, P.
    Held, H. Herrmann, C. Eigner, B. Brecht, L. Padberg, C. Silberhorn, Optics Express
    31 (2023).
date_created: 2023-07-03T14:08:36Z
date_updated: 2023-07-05T07:58:31Z
department:
- _id: '15'
- _id: '230'
- _id: '623'
- _id: '288'
doi: 10.1364/oe.484126
intvolume: '        31'
issue: '14'
keyword:
- Atomic and Molecular Physics
- and Optics
language:
- iso: eng
publication: Optics Express
publication_identifier:
  issn:
  - 1094-4087
publication_status: published
publisher: Optica Publishing Group
status: public
title: Demonstration of Hong-Ou-Mandel interference in an LNOI directional coupler
type: journal_article
user_id: '63231'
volume: 31
year: '2023'
...
---
_id: '42648'
abstract:
- lang: eng
  text: In real photonic quantum systems losses are an unavoidable factor limiting
    the scalability to many modes and particles, restraining their application in
    fields as quantum information and communication. For this reason, a considerable
    amount of engineering effort has been taken in order to improve the quality of
    particle sources and system components. At the same time, data analysis and collection
    methods based on post-selection have been used to mitigate the effect of particle
    losses. This has allowed for investigating experimentally multi-particle evolutions
    where the observer lacks knowledge about the system's intermediate propagation
    states. Nonetheless, the fundamental question how losses affect the behaviour
    of the surviving subset of a multi-particle system has not been investigated so
    far. For this reason, here we study the impact of particle losses in a quantum
    walk of two photons reconstructing the output probability distributions for one
    photon conditioned on the loss of the other in a known mode and temporal step
    of our evolution network. We present the underlying theoretical scheme that we
    have devised in order to model controlled particle losses, we describe an experimental
    platform capable of implementing our theory in a time multiplexing encoding. In
    the end we show how localized particle losses change the output distributions
    without altering their asymptotic spreading properties. Finally we devise a quantum
    civilization problem, a two walker generalisation of single particle recurrence
    processes.
article_number: '034005'
article_type: original
author:
- first_name: Federico
  full_name: Pegoraro, Federico
  id: '88928'
  last_name: Pegoraro
- first_name: Philip
  full_name: Held, Philip
  id: '68236'
  last_name: Held
- first_name: Sonja
  full_name: Barkhofen, Sonja
  id: '48188'
  last_name: Barkhofen
- first_name: Benjamin
  full_name: Brecht, Benjamin
  id: '27150'
  last_name: Brecht
  orcid: '0000-0003-4140-0556 '
- first_name: Christine
  full_name: Silberhorn, Christine
  id: '26263'
  last_name: Silberhorn
citation:
  ama: Pegoraro F, Held P, Barkhofen S, Brecht B, Silberhorn C. Dynamic conditioning
    of two particle discrete-time quantum walks. <i>Physica Scripta</i>. 2023;98(3).
    doi:<a href="https://doi.org/10.1088/1402-4896/acbcaa">10.1088/1402-4896/acbcaa</a>
  apa: Pegoraro, F., Held, P., Barkhofen, S., Brecht, B., &#38; Silberhorn, C. (2023).
    Dynamic conditioning of two particle discrete-time quantum walks. <i>Physica Scripta</i>,
    <i>98</i>(3), Article 034005. <a href="https://doi.org/10.1088/1402-4896/acbcaa">https://doi.org/10.1088/1402-4896/acbcaa</a>
  bibtex: '@article{Pegoraro_Held_Barkhofen_Brecht_Silberhorn_2023, title={Dynamic
    conditioning of two particle discrete-time quantum walks}, volume={98}, DOI={<a
    href="https://doi.org/10.1088/1402-4896/acbcaa">10.1088/1402-4896/acbcaa</a>},
    number={3034005}, journal={Physica Scripta}, publisher={IOP Publishing}, author={Pegoraro,
    Federico and Held, Philip and Barkhofen, Sonja and Brecht, Benjamin and Silberhorn,
    Christine}, year={2023} }'
  chicago: Pegoraro, Federico, Philip Held, Sonja Barkhofen, Benjamin Brecht, and
    Christine Silberhorn. “Dynamic Conditioning of Two Particle Discrete-Time Quantum
    Walks.” <i>Physica Scripta</i> 98, no. 3 (2023). <a href="https://doi.org/10.1088/1402-4896/acbcaa">https://doi.org/10.1088/1402-4896/acbcaa</a>.
  ieee: 'F. Pegoraro, P. Held, S. Barkhofen, B. Brecht, and C. Silberhorn, “Dynamic
    conditioning of two particle discrete-time quantum walks,” <i>Physica Scripta</i>,
    vol. 98, no. 3, Art. no. 034005, 2023, doi: <a href="https://doi.org/10.1088/1402-4896/acbcaa">10.1088/1402-4896/acbcaa</a>.'
  mla: Pegoraro, Federico, et al. “Dynamic Conditioning of Two Particle Discrete-Time
    Quantum Walks.” <i>Physica Scripta</i>, vol. 98, no. 3, 034005, IOP Publishing,
    2023, doi:<a href="https://doi.org/10.1088/1402-4896/acbcaa">10.1088/1402-4896/acbcaa</a>.
  short: F. Pegoraro, P. Held, S. Barkhofen, B. Brecht, C. Silberhorn, Physica Scripta
    98 (2023).
date_created: 2023-03-02T09:53:59Z
date_updated: 2026-01-09T09:49:31Z
department:
- _id: '623'
- _id: '15'
- _id: '288'
- _id: '169'
doi: 10.1088/1402-4896/acbcaa
intvolume: '        98'
issue: '3'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://iopscience.iop.org/article/10.1088/1402-4896/acbcaa
oa: '1'
publication: Physica Scripta
publication_identifier:
  issn:
  - 0031-8949
  - 1402-4896
publication_status: published
publisher: IOP Publishing
status: public
title: Dynamic conditioning of two particle discrete-time quantum walks
type: journal_article
user_id: '68236'
volume: 98
year: '2023'
...