---
_id: '58519'
abstract:
- lang: eng
  text: <jats:p>A unified theoretical approach to describe the properties of multimode
    squeezed light generated in a lossy medium is presented. This approach is valid
    for Markovian environments and includes both a model of discrete losses based
    on the beamsplitter approach and a generalized continuous loss model based on
    the spatial Langevin equation. For an important class of Gaussian states, we derive
    master equations for the second-order correlation functions and illustrate their
    solution for both frequency-independent and frequency-dependent losses. Studying
    the mode structure, we demonstrate that in a lossy environment no broadband basis
    without quadrature correlations between the different broadband modes exists.
    Therefore, various techniques and strategies to introduce broadband modes can
    be considered. We show that the Mercer expansion and the Williamson-Euler decomposition
    do not provide modes in which the maximal squeezing contained in the system can
    be measured. In turn, we find a new broadband basis that maximizes squeezing in
    the lossy system and present an algorithm to construct it.</jats:p>
article_number: '1621'
author:
- first_name: Denis A.
  full_name: Kopylov, Denis A.
  last_name: Kopylov
- first_name: Torsten
  full_name: Meier, Torsten
  id: '344'
  last_name: Meier
  orcid: 0000-0001-8864-2072
- first_name: Polina R.
  full_name: Sharapova, Polina R.
  id: '60286'
  last_name: Sharapova
citation:
  ama: Kopylov DA, Meier T, Sharapova PR. Theory of Multimode Squeezed Light Generation
    in Lossy Media. <i>Quantum</i>. 2025;9. doi:<a href="https://doi.org/10.22331/q-2025-02-04-1621">10.22331/q-2025-02-04-1621</a>
  apa: Kopylov, D. A., Meier, T., &#38; Sharapova, P. R. (2025). Theory of Multimode
    Squeezed Light Generation in Lossy Media. <i>Quantum</i>, <i>9</i>, Article 1621.
    <a href="https://doi.org/10.22331/q-2025-02-04-1621">https://doi.org/10.22331/q-2025-02-04-1621</a>
  bibtex: '@article{Kopylov_Meier_Sharapova_2025, title={Theory of Multimode Squeezed
    Light Generation in Lossy Media}, volume={9}, DOI={<a href="https://doi.org/10.22331/q-2025-02-04-1621">10.22331/q-2025-02-04-1621</a>},
    number={1621}, journal={Quantum}, publisher={Verein zur Forderung des Open Access
    Publizierens in den Quantenwissenschaften}, author={Kopylov, Denis A. and Meier,
    Torsten and Sharapova, Polina R.}, year={2025} }'
  chicago: Kopylov, Denis A., Torsten Meier, and Polina R. Sharapova. “Theory of Multimode
    Squeezed Light Generation in Lossy Media.” <i>Quantum</i> 9 (2025). <a href="https://doi.org/10.22331/q-2025-02-04-1621">https://doi.org/10.22331/q-2025-02-04-1621</a>.
  ieee: 'D. A. Kopylov, T. Meier, and P. R. Sharapova, “Theory of Multimode Squeezed
    Light Generation in Lossy Media,” <i>Quantum</i>, vol. 9, Art. no. 1621, 2025,
    doi: <a href="https://doi.org/10.22331/q-2025-02-04-1621">10.22331/q-2025-02-04-1621</a>.'
  mla: Kopylov, Denis A., et al. “Theory of Multimode Squeezed Light Generation in
    Lossy Media.” <i>Quantum</i>, vol. 9, 1621, Verein zur Forderung des Open Access
    Publizierens in den Quantenwissenschaften, 2025, doi:<a href="https://doi.org/10.22331/q-2025-02-04-1621">10.22331/q-2025-02-04-1621</a>.
  short: D.A. Kopylov, T. Meier, P.R. Sharapova, Quantum 9 (2025).
date_created: 2025-02-05T12:57:37Z
date_updated: 2025-09-18T13:22:26Z
department:
- _id: '15'
- _id: '569'
- _id: '170'
- _id: '293'
- _id: '35'
- _id: '230'
- _id: '623'
- _id: '27'
doi: 10.22331/q-2025-02-04-1621
intvolume: '         9'
language:
- iso: eng
project:
- _id: '266'
  name: 'PhoQC: PhoQC: Photonisches Quantencomputing'
- _id: '52'
  name: Computing Resources Provided by the Paderborn Center for Parallel Computing
publication: Quantum
publication_identifier:
  issn:
  - 2521-327X
publication_status: published
publisher: Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften
status: public
title: Theory of Multimode Squeezed Light Generation in Lossy Media
type: journal_article
user_id: '16199'
volume: 9
year: '2025'
...
---
_id: '29780'
abstract:
- lang: eng
  text: <jats:p>A central tenet of theoretical cryptography is the study of the minimal
    assumptions required to implement a given cryptographic primitive. One such primitive
    is the one-time memory (OTM), introduced by Goldwasser, Kalai, and Rothblum [CRYPTO
    2008], which is a classical functionality modeled after a non-interactive 1-out-of-2
    oblivious transfer, and which is complete for one-time classical and quantum programs.
    It is known that secure OTMs do not exist in the standard model in both the classical
    and quantum settings. Here, we propose a scheme for using quantum information,
    together with the assumption of stateless (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>i</mml:mi><mml:mo>.</mml:mo><mml:mi>e</mml:mi><mml:mo>.</mml:mo></mml:math>,
    reusable) hardware tokens, to build statistically secure OTMs. Via the semidefinite
    programming-based quantum games framework of Gutoski and Watrous [STOC 2007],
    we prove security for a malicious receiver making at most 0.114<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>n</mml:mi></mml:math>
    adaptive queries to the token (for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>n</mml:mi></mml:math>
    the key size), in the quantum universal composability framework, but leave open
    the question of security against a polynomial amount of queries. Compared to alternative
    schemes derived from the literature on quantum money, our scheme is technologically
    simple since it is of the "prepare-and-measure" type. We also give two impossibility
    results showing certain assumptions in our scheme cannot be relaxed.</jats:p>
article_number: '429'
author:
- first_name: Anne
  full_name: Broadbent, Anne
  last_name: Broadbent
- first_name: Sevag
  full_name: Gharibian, Sevag
  id: '71541'
  last_name: Gharibian
  orcid: 0000-0002-9992-3379
- first_name: Hong-Sheng
  full_name: Zhou, Hong-Sheng
  last_name: Zhou
citation:
  ama: Broadbent A, Gharibian S, Zhou H-S. Towards Quantum One-Time Memories from
    Stateless Hardware. <i>Quantum</i>. 2021;5. doi:<a href="https://doi.org/10.22331/q-2021-04-08-429">10.22331/q-2021-04-08-429</a>
  apa: Broadbent, A., Gharibian, S., &#38; Zhou, H.-S. (2021). Towards Quantum One-Time
    Memories from Stateless Hardware. <i>Quantum</i>, <i>5</i>, Article 429. <a href="https://doi.org/10.22331/q-2021-04-08-429">https://doi.org/10.22331/q-2021-04-08-429</a>
  bibtex: '@article{Broadbent_Gharibian_Zhou_2021, title={Towards Quantum One-Time
    Memories from Stateless Hardware}, volume={5}, DOI={<a href="https://doi.org/10.22331/q-2021-04-08-429">10.22331/q-2021-04-08-429</a>},
    number={429}, journal={Quantum}, publisher={Verein zur Forderung des Open Access
    Publizierens in den Quantenwissenschaften}, author={Broadbent, Anne and Gharibian,
    Sevag and Zhou, Hong-Sheng}, year={2021} }'
  chicago: Broadbent, Anne, Sevag Gharibian, and Hong-Sheng Zhou. “Towards Quantum
    One-Time Memories from Stateless Hardware.” <i>Quantum</i> 5 (2021). <a href="https://doi.org/10.22331/q-2021-04-08-429">https://doi.org/10.22331/q-2021-04-08-429</a>.
  ieee: 'A. Broadbent, S. Gharibian, and H.-S. Zhou, “Towards Quantum One-Time Memories
    from Stateless Hardware,” <i>Quantum</i>, vol. 5, Art. no. 429, 2021, doi: <a
    href="https://doi.org/10.22331/q-2021-04-08-429">10.22331/q-2021-04-08-429</a>.'
  mla: Broadbent, Anne, et al. “Towards Quantum One-Time Memories from Stateless Hardware.”
    <i>Quantum</i>, vol. 5, 429, Verein zur Forderung des Open Access Publizierens
    in den Quantenwissenschaften, 2021, doi:<a href="https://doi.org/10.22331/q-2021-04-08-429">10.22331/q-2021-04-08-429</a>.
  short: A. Broadbent, S. Gharibian, H.-S. Zhou, Quantum 5 (2021).
date_created: 2022-02-08T10:59:00Z
date_updated: 2023-02-28T11:07:47Z
department:
- _id: '623'
- _id: '7'
doi: 10.22331/q-2021-04-08-429
intvolume: '         5'
keyword:
- Physics and Astronomy (miscellaneous)
- Atomic and Molecular Physics
- and Optics
language:
- iso: eng
publication: Quantum
publication_identifier:
  issn:
  - 2521-327X
publication_status: published
publisher: Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften
status: public
title: Towards Quantum One-Time Memories from Stateless Hardware
type: journal_article
user_id: '71541'
volume: 5
year: '2021'
...
---
_id: '26077'
abstract:
- lang: eng
  text: <jats:p>Nonlinear SU(1,1) interferometers are fruitful and promising tools
    for spectral engineering and precise measurements with phase sensitivity below
    the classical bound. Such interferometers have been successfully realized in bulk
    and fiber-based configurations. However, rapidly developing integrated technologies
    provide higher efficiencies, smaller footprints, and pave the way to quantum-enhanced
    on-chip interferometry. In this work, we theoretically realised an integrated
    architecture of the multimode SU(1,1) interferometer which can be applied to various
    integrated platforms. The presented interferometer includes a polarization converter
    between two photon sources and utilizes a continuous-wave (CW) pump. Based on
    the potassium titanyl phosphate (KTP) platform, we show that this configuration
    results in almost perfect destructive interference at the output and supersensitivity
    regions below the classical limit. In addition, we discuss the fundamental difference
    between single-mode and highly multimode SU(1,1) interferometers in the properties
    of phase sensitivity and its limits. Finally, we explore how to improve the phase
    sensitivity by filtering the output radiation and using different seeding states
    in different modes with various detection strategies.</jats:p>
article_number: '461'
author:
- first_name: Alessandro
  full_name: Ferreri, Alessandro
  id: '65609'
  last_name: Ferreri
- first_name: Matteo
  full_name: Santandrea, Matteo
  id: '55095'
  last_name: Santandrea
  orcid: 0000-0001-5718-358X
- first_name: Michael
  full_name: Stefszky, Michael
  id: '42777'
  last_name: Stefszky
- first_name: Kai Hong
  full_name: Luo, Kai Hong
  id: '36389'
  last_name: Luo
  orcid: 0000-0003-1008-4976
- first_name: Harald
  full_name: Herrmann, Harald
  id: '216'
  last_name: Herrmann
- first_name: Christine
  full_name: Silberhorn, Christine
  id: '26263'
  last_name: Silberhorn
- first_name: Polina R.
  full_name: Sharapova, Polina R.
  id: '60286'
  last_name: Sharapova
citation:
  ama: Ferreri A, Santandrea M, Stefszky M, et al. Spectrally multimode integrated
    SU(1,1) interferometer. <i>Quantum</i>. Published online 2021. doi:<a href="https://doi.org/10.22331/q-2021-05-27-461">10.22331/q-2021-05-27-461</a>
  apa: Ferreri, A., Santandrea, M., Stefszky, M., Luo, K. H., Herrmann, H., Silberhorn,
    C., &#38; Sharapova, P. R. (2021). Spectrally multimode integrated SU(1,1) interferometer.
    <i>Quantum</i>, Article 461. <a href="https://doi.org/10.22331/q-2021-05-27-461">https://doi.org/10.22331/q-2021-05-27-461</a>
  bibtex: '@article{Ferreri_Santandrea_Stefszky_Luo_Herrmann_Silberhorn_Sharapova_2021,
    title={Spectrally multimode integrated SU(1,1) interferometer}, DOI={<a href="https://doi.org/10.22331/q-2021-05-27-461">10.22331/q-2021-05-27-461</a>},
    number={461}, journal={Quantum}, author={Ferreri, Alessandro and Santandrea, Matteo
    and Stefszky, Michael and Luo, Kai Hong and Herrmann, Harald and Silberhorn, Christine
    and Sharapova, Polina R.}, year={2021} }'
  chicago: Ferreri, Alessandro, Matteo Santandrea, Michael Stefszky, Kai Hong Luo,
    Harald Herrmann, Christine Silberhorn, and Polina R. Sharapova. “Spectrally Multimode
    Integrated SU(1,1) Interferometer.” <i>Quantum</i>, 2021. <a href="https://doi.org/10.22331/q-2021-05-27-461">https://doi.org/10.22331/q-2021-05-27-461</a>.
  ieee: 'A. Ferreri <i>et al.</i>, “Spectrally multimode integrated SU(1,1) interferometer,”
    <i>Quantum</i>, Art. no. 461, 2021, doi: <a href="https://doi.org/10.22331/q-2021-05-27-461">10.22331/q-2021-05-27-461</a>.'
  mla: Ferreri, Alessandro, et al. “Spectrally Multimode Integrated SU(1,1) Interferometer.”
    <i>Quantum</i>, 461, 2021, doi:<a href="https://doi.org/10.22331/q-2021-05-27-461">10.22331/q-2021-05-27-461</a>.
  short: A. Ferreri, M. Santandrea, M. Stefszky, K.H. Luo, H. Herrmann, C. Silberhorn,
    P.R. Sharapova, Quantum (2021).
date_created: 2021-10-12T08:46:46Z
date_updated: 2026-01-16T10:22:10Z
department:
- _id: '15'
- _id: '288'
doi: 10.22331/q-2021-05-27-461
language:
- iso: eng
project:
- _id: '56'
  name: 'TRR 142 - C: TRR 142 - Project Area C'
publication: Quantum
publication_identifier:
  issn:
  - 2521-327X
publication_status: published
status: public
title: Spectrally multimode integrated SU(1,1) interferometer
type: journal_article
user_id: '42777'
year: '2021'
...
---
_id: '26290'
abstract:
- lang: eng
  text: <jats:p>We devise a method to certify nonclassical features via correlations
    of phase-space distributions by unifying the notions of quasiprobabilities and
    matrices of correlation functions. Our approach complements and extends recent
    results that were based on Chebyshev's integral inequality \cite{BA19}. The method
    developed here correlates arbitrary phase-space functions at arbitrary points
    in phase space, including multimode scenarios and higher-order correlations. Furthermore,
    our approach provides necessary and sufficient nonclassicality criteria, applies
    to phase-space functions beyond <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>s</mml:mi></mml:math>-parametrized
    ones, and is accessible in experiments. To demonstrate the power of our technique,
    the quantum characteristics of discrete- and continuous-variable, single- and
    multimode, as well as pure and mixed states are certified only employing second-order
    correlations and Husimi functions, which always resemble a classical probability
    distribution. Moreover, nonlinear generalizations of our approach are studied.
    Therefore, a versatile and broadly applicable framework is devised to uncover
    quantum properties in terms of matrices of phase-space distributions.</jats:p>
article_number: '343'
author:
- first_name: Martin
  full_name: Bohmann, Martin
  last_name: Bohmann
- first_name: Elizabeth
  full_name: Agudelo, Elizabeth
  last_name: Agudelo
- first_name: Jan
  full_name: Sperling, Jan
  id: '75127'
  last_name: Sperling
  orcid: 0000-0002-5844-3205
citation:
  ama: Bohmann M, Agudelo E, Sperling J. Probing nonclassicality with matrices of
    phase-space distributions. <i>Quantum</i>. Published online 2020. doi:<a href="https://doi.org/10.22331/q-2020-10-15-343">10.22331/q-2020-10-15-343</a>
  apa: Bohmann, M., Agudelo, E., &#38; Sperling, J. (2020). Probing nonclassicality
    with matrices of phase-space distributions. <i>Quantum</i>, Article 343. <a href="https://doi.org/10.22331/q-2020-10-15-343">https://doi.org/10.22331/q-2020-10-15-343</a>
  bibtex: '@article{Bohmann_Agudelo_Sperling_2020, title={Probing nonclassicality
    with matrices of phase-space distributions}, DOI={<a href="https://doi.org/10.22331/q-2020-10-15-343">10.22331/q-2020-10-15-343</a>},
    number={343}, journal={Quantum}, author={Bohmann, Martin and Agudelo, Elizabeth
    and Sperling, Jan}, year={2020} }'
  chicago: Bohmann, Martin, Elizabeth Agudelo, and Jan Sperling. “Probing Nonclassicality
    with Matrices of Phase-Space Distributions.” <i>Quantum</i>, 2020. <a href="https://doi.org/10.22331/q-2020-10-15-343">https://doi.org/10.22331/q-2020-10-15-343</a>.
  ieee: 'M. Bohmann, E. Agudelo, and J. Sperling, “Probing nonclassicality with matrices
    of phase-space distributions,” <i>Quantum</i>, Art. no. 343, 2020, doi: <a href="https://doi.org/10.22331/q-2020-10-15-343">10.22331/q-2020-10-15-343</a>.'
  mla: Bohmann, Martin, et al. “Probing Nonclassicality with Matrices of Phase-Space
    Distributions.” <i>Quantum</i>, 343, 2020, doi:<a href="https://doi.org/10.22331/q-2020-10-15-343">10.22331/q-2020-10-15-343</a>.
  short: M. Bohmann, E. Agudelo, J. Sperling, Quantum (2020).
date_created: 2021-10-15T16:10:46Z
date_updated: 2023-04-20T15:12:58Z
department:
- _id: '15'
- _id: '170'
- _id: '706'
- _id: '35'
doi: 10.22331/q-2020-10-15-343
language:
- iso: eng
publication: Quantum
publication_identifier:
  issn:
  - 2521-327X
publication_status: published
status: public
title: Probing nonclassicality with matrices of phase-space distributions
type: journal_article
user_id: '16199'
year: '2020'
...