---
_id: '56267'
author:
- first_name: Laura
  full_name: Serino, Laura
  id: '88242'
  last_name: Serino
- first_name: Werner
  full_name: Ridder, Werner
  id: '63574'
  last_name: Ridder
- first_name: Abhinandan
  full_name: Bhattacharjee, Abhinandan
  id: '95902'
  last_name: Bhattacharjee
- first_name: Jano
  full_name: Gil López, Jano
  id: '51223'
  last_name: Gil López
- 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: 'Serino L, Ridder W, Bhattacharjee A, Gil López J, Brecht B, Silberhorn C.
    Orchestrating time and color: a programmable source of high-dimensional entanglement.
    <i>Optica Quantum</i>. Published online 2024. doi:<a href="https://doi.org/10.1364/opticaq.532334">10.1364/opticaq.532334</a>'
  apa: 'Serino, L., Ridder, W., Bhattacharjee, A., Gil López, J., Brecht, B., &#38;
    Silberhorn, C. (2024). Orchestrating time and color: a programmable source of
    high-dimensional entanglement. <i>Optica Quantum</i>. <a href="https://doi.org/10.1364/opticaq.532334">https://doi.org/10.1364/opticaq.532334</a>'
  bibtex: '@article{Serino_Ridder_Bhattacharjee_Gil López_Brecht_Silberhorn_2024,
    title={Orchestrating time and color: a programmable source of high-dimensional
    entanglement}, DOI={<a href="https://doi.org/10.1364/opticaq.532334">10.1364/opticaq.532334</a>},
    journal={Optica Quantum}, publisher={Optica Publishing Group}, author={Serino,
    Laura and Ridder, Werner and Bhattacharjee, Abhinandan and Gil López, Jano and
    Brecht, Benjamin and Silberhorn, Christine}, year={2024} }'
  chicago: 'Serino, Laura, Werner Ridder, Abhinandan Bhattacharjee, Jano Gil López,
    Benjamin Brecht, and Christine Silberhorn. “Orchestrating Time and Color: A Programmable
    Source of High-Dimensional Entanglement.” <i>Optica Quantum</i>, 2024. <a href="https://doi.org/10.1364/opticaq.532334">https://doi.org/10.1364/opticaq.532334</a>.'
  ieee: 'L. Serino, W. Ridder, A. Bhattacharjee, J. Gil López, B. Brecht, and C. Silberhorn,
    “Orchestrating time and color: a programmable source of high-dimensional entanglement,”
    <i>Optica Quantum</i>, 2024, doi: <a href="https://doi.org/10.1364/opticaq.532334">10.1364/opticaq.532334</a>.'
  mla: 'Serino, Laura, et al. “Orchestrating Time and Color: A Programmable Source
    of High-Dimensional Entanglement.” <i>Optica Quantum</i>, Optica Publishing Group,
    2024, doi:<a href="https://doi.org/10.1364/opticaq.532334">10.1364/opticaq.532334</a>.'
  short: L. Serino, W. Ridder, A. Bhattacharjee, J. Gil López, B. Brecht, C. Silberhorn,
    Optica Quantum (2024).
date_created: 2024-09-27T11:46:59Z
date_updated: 2025-12-01T08:49:46Z
department:
- _id: '288'
- _id: '623'
- _id: '288'
doi: 10.1364/opticaq.532334
language:
- iso: eng
project:
- _id: '211'
  name: 'QuICHE: Quanteninformation und Quantenkommunikation mit hochdimensionaler
    Informationskodierung (QuICHE)'
publication: Optica Quantum
publication_identifier:
  issn:
  - 2837-6714
publication_status: published
publisher: Optica Publishing Group
status: public
title: 'Orchestrating time and color: a programmable source of high-dimensional entanglement'
type: journal_article
user_id: '63574'
year: '2024'
...
---
_id: '63216'
abstract:
- lang: eng
  text: <jats:p>The characterization of the complex spectral amplitude, that is, the
    spectrum and spectral phase, of single-photon-level light fields is a crucial
    capability for modern photonic quantum technologies. Since established pulse characterization
    techniques are not applicable at low intensities, alternative approaches are required.
    Here, we demonstrate the retrieval of the complex spectral amplitude of single-photon-level
    light pulses through measuring their chronocyclic <jats:italic toggle="yes">Q</jats:italic> −function.
    Our approach draws inspiration from quantum state tomography by exploiting the
    analogy between quadrature phase space and time-frequency phase space. In the
    experiment, we perform time-frequency projections with a quantum pulse gate (QPG),
    which directly yield the chronocyclic <jats:italic toggle="yes">Q</jats:italic> −function.
    We evaluate the complex spectral amplitude from the measured chronocyclic <jats:italic
    toggle="yes">Q</jats:italic> −function data with maximum likelihood estimation
    (MLE), which is the established technique for quantum state tomography. The MLE
    yields not only an unambigious estimate of the complex spectral amplitude of the
    state under test that does not require any <jats:italic toggle="yes">a priori</jats:italic>
    information, but also allows for, in principle, estimating the spectral-temporal
    coherence properties of the state. Our method accurately recovers features such
    as jumps in the spectral phase and is resistant against regions with zero spectral
    intensity, which makes it immediately beneficial for classical pulse characterization
    problems.</jats:p>
article_number: '5551'
author:
- first_name: Abhinandan
  full_name: Bhattacharjee, Abhinandan
  id: '95902'
  last_name: Bhattacharjee
- first_name: Patrick Fabian
  full_name: Folge, Patrick Fabian
  id: '88605'
  last_name: Folge
- first_name: Laura Maria
  full_name: Serino, Laura Maria
  id: '88242'
  last_name: Serino
- first_name: Jaroslav
  full_name: Řeháček, Jaroslav
  last_name: Řeháček
- first_name: Zdeněk
  full_name: Hradil, Zdeněk
  last_name: Hradil
- first_name: Christine
  full_name: Silberhorn, Christine
  id: '26263'
  last_name: Silberhorn
- first_name: Benjamin
  full_name: Brecht, Benjamin
  id: '27150'
  last_name: Brecht
  orcid: '0000-0003-4140-0556 '
citation:
  ama: Bhattacharjee A, Folge PF, Serino LM, et al. Pulse characterization at the
    single-photon level through chronocyclic <i>Q</i>-function measurements. <i>Optics
    Express</i>. 2024;33(3). doi:<a href="https://doi.org/10.1364/oe.540125">10.1364/oe.540125</a>
  apa: Bhattacharjee, A., Folge, P. F., Serino, L. M., Řeháček, J., Hradil, Z., Silberhorn,
    C., &#38; Brecht, B. (2024). Pulse characterization at the single-photon level
    through chronocyclic <i>Q</i>-function measurements. <i>Optics Express</i>, <i>33</i>(3),
    Article 5551. <a href="https://doi.org/10.1364/oe.540125">https://doi.org/10.1364/oe.540125</a>
  bibtex: '@article{Bhattacharjee_Folge_Serino_Řeháček_Hradil_Silberhorn_Brecht_2024,
    title={Pulse characterization at the single-photon level through chronocyclic
    <i>Q</i>-function measurements}, volume={33}, DOI={<a href="https://doi.org/10.1364/oe.540125">10.1364/oe.540125</a>},
    number={35551}, journal={Optics Express}, publisher={Optica Publishing Group},
    author={Bhattacharjee, Abhinandan and Folge, Patrick Fabian and Serino, Laura
    Maria and Řeháček, Jaroslav and Hradil, Zdeněk and Silberhorn, Christine and Brecht,
    Benjamin}, year={2024} }'
  chicago: Bhattacharjee, Abhinandan, Patrick Fabian Folge, Laura Maria Serino, Jaroslav
    Řeháček, Zdeněk Hradil, Christine Silberhorn, and Benjamin Brecht. “Pulse Characterization
    at the Single-Photon Level through Chronocyclic <i>Q</i>-Function Measurements.”
    <i>Optics Express</i> 33, no. 3 (2024). <a href="https://doi.org/10.1364/oe.540125">https://doi.org/10.1364/oe.540125</a>.
  ieee: 'A. Bhattacharjee <i>et al.</i>, “Pulse characterization at the single-photon
    level through chronocyclic <i>Q</i>-function measurements,” <i>Optics Express</i>,
    vol. 33, no. 3, Art. no. 5551, 2024, doi: <a href="https://doi.org/10.1364/oe.540125">10.1364/oe.540125</a>.'
  mla: Bhattacharjee, Abhinandan, et al. “Pulse Characterization at the Single-Photon
    Level through Chronocyclic <i>Q</i>-Function Measurements.” <i>Optics Express</i>,
    vol. 33, no. 3, 5551, Optica Publishing Group, 2024, doi:<a href="https://doi.org/10.1364/oe.540125">10.1364/oe.540125</a>.
  short: A. Bhattacharjee, P.F. Folge, L.M. Serino, J. Řeháček, Z. Hradil, C. Silberhorn,
    B. Brecht, Optics Express 33 (2024).
date_created: 2025-12-18T16:08:16Z
date_updated: 2025-12-18T16:08:40Z
department:
- _id: '15'
- _id: '623'
doi: 10.1364/oe.540125
intvolume: '        33'
issue: '3'
language:
- iso: eng
publication: Optics Express
publication_identifier:
  issn:
  - 1094-4087
publication_status: published
publisher: Optica Publishing Group
status: public
title: Pulse characterization at the single-photon level through chronocyclic <i>Q</i>-function
  measurements
type: journal_article
user_id: '27150'
volume: 33
year: '2024'
...