---
_id: '62849'
abstract:
- lang: eng
  text: <jats:title>Abstract</jats:title><jats:p>An on-demand source of bright entangled
    photon pairs is desirable for quantum key distribution (QKD) and quantum repeaters.
    The leading candidate to generate such pairs is based on spontaneous parametric
    down-conversion (SPDC) in non-linear crystals. However, its pair extraction efficiency
    is limited to 0.1% when operating at near-unity fidelity due to multiphoton emission
    at high brightness. Quantum dots in photonic nanostructures can in principle overcome
    this limit, but the devices with high entanglement fidelity (99%) have low pair
    extraction efficiency (0.01%). Here, we show a measured peak entanglement fidelity
    of 97.5% ± 0.8% and pair extraction efficiency of 0.65% from an InAsP quantum
    dot in an InP photonic nanowire waveguide. We show that the generated oscillating
    two-photon Bell state can establish a secure key for peer-to-peer QKD. Using our
    time-resolved QKD scheme alleviates the need to remove the quantum dot energy
    splitting of the intermediate exciton states in the biexciton-exciton cascade.</jats:p>
article_number: '62'
author:
- first_name: Matteo
  full_name: Pennacchietti, Matteo
  last_name: Pennacchietti
- first_name: Brady
  full_name: Cunard, Brady
  last_name: Cunard
- first_name: Shlok
  full_name: Nahar, Shlok
  last_name: Nahar
- first_name: Mohd
  full_name: Zeeshan, Mohd
  last_name: Zeeshan
- first_name: Sayan
  full_name: Gangopadhyay, Sayan
  last_name: Gangopadhyay
- first_name: Philip J.
  full_name: Poole, Philip J.
  last_name: Poole
- first_name: Dan
  full_name: Dalacu, Dan
  last_name: Dalacu
- first_name: Andreas
  full_name: Fognini, Andreas
  last_name: Fognini
- first_name: Klaus
  full_name: Jöns, Klaus
  id: '85353'
  last_name: Jöns
- first_name: Val
  full_name: Zwiller, Val
  last_name: Zwiller
- first_name: Thomas
  full_name: Jennewein, Thomas
  last_name: Jennewein
- first_name: Norbert
  full_name: Lütkenhaus, Norbert
  last_name: Lütkenhaus
- first_name: Michael E.
  full_name: Reimer, Michael E.
  last_name: Reimer
citation:
  ama: Pennacchietti M, Cunard B, Nahar S, et al. Oscillating photonic Bell state
    from a semiconductor quantum dot for quantum key distribution. <i>Communications
    Physics</i>. 2024;7(1). doi:<a href="https://doi.org/10.1038/s42005-024-01547-3">10.1038/s42005-024-01547-3</a>
  apa: Pennacchietti, M., Cunard, B., Nahar, S., Zeeshan, M., Gangopadhyay, S., Poole,
    P. J., Dalacu, D., Fognini, A., Jöns, K., Zwiller, V., Jennewein, T., Lütkenhaus,
    N., &#38; Reimer, M. E. (2024). Oscillating photonic Bell state from a semiconductor
    quantum dot for quantum key distribution. <i>Communications Physics</i>, <i>7</i>(1),
    Article 62. <a href="https://doi.org/10.1038/s42005-024-01547-3">https://doi.org/10.1038/s42005-024-01547-3</a>
  bibtex: '@article{Pennacchietti_Cunard_Nahar_Zeeshan_Gangopadhyay_Poole_Dalacu_Fognini_Jöns_Zwiller_et
    al._2024, title={Oscillating photonic Bell state from a semiconductor quantum
    dot for quantum key distribution}, volume={7}, DOI={<a href="https://doi.org/10.1038/s42005-024-01547-3">10.1038/s42005-024-01547-3</a>},
    number={162}, journal={Communications Physics}, publisher={Springer Science and
    Business Media LLC}, author={Pennacchietti, Matteo and Cunard, Brady and Nahar,
    Shlok and Zeeshan, Mohd and Gangopadhyay, Sayan and Poole, Philip J. and Dalacu,
    Dan and Fognini, Andreas and Jöns, Klaus and Zwiller, Val and et al.}, year={2024}
    }'
  chicago: Pennacchietti, Matteo, Brady Cunard, Shlok Nahar, Mohd Zeeshan, Sayan Gangopadhyay,
    Philip J. Poole, Dan Dalacu, et al. “Oscillating Photonic Bell State from a Semiconductor
    Quantum Dot for Quantum Key Distribution.” <i>Communications Physics</i> 7, no.
    1 (2024). <a href="https://doi.org/10.1038/s42005-024-01547-3">https://doi.org/10.1038/s42005-024-01547-3</a>.
  ieee: 'M. Pennacchietti <i>et al.</i>, “Oscillating photonic Bell state from a semiconductor
    quantum dot for quantum key distribution,” <i>Communications Physics</i>, vol.
    7, no. 1, Art. no. 62, 2024, doi: <a href="https://doi.org/10.1038/s42005-024-01547-3">10.1038/s42005-024-01547-3</a>.'
  mla: Pennacchietti, Matteo, et al. “Oscillating Photonic Bell State from a Semiconductor
    Quantum Dot for Quantum Key Distribution.” <i>Communications Physics</i>, vol.
    7, no. 1, 62, Springer Science and Business Media LLC, 2024, doi:<a href="https://doi.org/10.1038/s42005-024-01547-3">10.1038/s42005-024-01547-3</a>.
  short: M. Pennacchietti, B. Cunard, S. Nahar, M. Zeeshan, S. Gangopadhyay, P.J.
    Poole, D. Dalacu, A. Fognini, K. Jöns, V. Zwiller, T. Jennewein, N. Lütkenhaus,
    M.E. Reimer, Communications Physics 7 (2024).
date_created: 2025-12-04T12:03:50Z
date_updated: 2025-12-04T12:23:54Z
department:
- _id: '623'
doi: 10.1038/s42005-024-01547-3
intvolume: '         7'
issue: '1'
language:
- iso: eng
publication: Communications Physics
publication_identifier:
  issn:
  - 2399-3650
publication_status: published
publisher: Springer Science and Business Media LLC
status: public
title: Oscillating photonic Bell state from a semiconductor quantum dot for quantum
  key distribution
type: journal_article
user_id: '48188'
volume: 7
year: '2024'
...
---
_id: '20773'
abstract:
- lang: eng
  text: <jats:title>Abstract</jats:title><jats:p>Semiconductor quantum dots are excellent
    candidates for ultrafast coherent manipulation of qubits by laser pulses on picosecond
    timescales or even faster. In inhomogeneous ensembles a macroscopic optical polarization
    decays rapidly due to dephasing, which, however, is reversible in photon echoes
    carrying complete information about the coherent ensemble dynamics. Control of
    the echo emission time is mandatory for applications. Here, we propose a concept
    to reach this goal. In a two-pulse photon echo sequence, we apply an additional
    resonant control pulse with multiple of 2<jats:italic>π</jats:italic> area. Depending
    on its arrival time, the control slows down dephasing or rephasing of the exciton
    ensemble during its action. We demonstrate for self-assembled (In,Ga)As quantum
    dots that the photon echo emission time can be retarded or advanced by up to 5
    ps relative to its nominal appearance time without control. This versatile protocol
    may be used to obtain significantly longer temporal shifts for suitably tailored
    control pulses.</jats:p>
article_number: '228'
author:
- first_name: Alexander N.
  full_name: Kosarev, Alexander N.
  last_name: Kosarev
- first_name: Hendrik
  full_name: Rose, Hendrik
  id: '55958'
  last_name: Rose
  orcid: 0000-0002-3079-5428
- first_name: Sergey V.
  full_name: Poltavtsev, Sergey V.
  last_name: Poltavtsev
- first_name: Matthias
  full_name: Reichelt, Matthias
  id: '138'
  last_name: Reichelt
- first_name: Christian
  full_name: Schneider, Christian
  last_name: Schneider
- first_name: Martin
  full_name: Kamp, Martin
  last_name: Kamp
- first_name: Sven
  full_name: Höfling, Sven
  last_name: Höfling
- first_name: Manfred
  full_name: Bayer, Manfred
  last_name: Bayer
- first_name: Torsten
  full_name: Meier, Torsten
  id: '344'
  last_name: Meier
  orcid: 0000-0001-8864-2072
- first_name: Ilya A.
  full_name: Akimov, Ilya A.
  last_name: Akimov
citation:
  ama: Kosarev AN, Rose H, Poltavtsev SV, et al. Accurate photon echo timing by optical
    freezing of exciton dephasing and rephasing in quantum dots. <i>Communications
    Physics</i>. 2020;3(1). doi:<a href="https://doi.org/10.1038/s42005-020-00491-2">10.1038/s42005-020-00491-2</a>
  apa: Kosarev, A. N., Rose, H., Poltavtsev, S. V., Reichelt, M., Schneider, C., Kamp,
    M., Höfling, S., Bayer, M., Meier, T., &#38; Akimov, I. A. (2020). Accurate photon
    echo timing by optical freezing of exciton dephasing and rephasing in quantum
    dots. <i>Communications Physics</i>, <i>3</i>(1), Article 228. <a href="https://doi.org/10.1038/s42005-020-00491-2">https://doi.org/10.1038/s42005-020-00491-2</a>
  bibtex: '@article{Kosarev_Rose_Poltavtsev_Reichelt_Schneider_Kamp_Höfling_Bayer_Meier_Akimov_2020,
    title={Accurate photon echo timing by optical freezing of exciton dephasing and
    rephasing in quantum dots}, volume={3}, DOI={<a href="https://doi.org/10.1038/s42005-020-00491-2">10.1038/s42005-020-00491-2</a>},
    number={1228}, journal={Communications Physics}, author={Kosarev, Alexander N.
    and Rose, Hendrik and Poltavtsev, Sergey V. and Reichelt, Matthias and Schneider,
    Christian and Kamp, Martin and Höfling, Sven and Bayer, Manfred and Meier, Torsten
    and Akimov, Ilya A.}, year={2020} }'
  chicago: Kosarev, Alexander N., Hendrik Rose, Sergey V. Poltavtsev, Matthias Reichelt,
    Christian Schneider, Martin Kamp, Sven Höfling, Manfred Bayer, Torsten Meier,
    and Ilya A. Akimov. “Accurate Photon Echo Timing by Optical Freezing of Exciton
    Dephasing and Rephasing in Quantum Dots.” <i>Communications Physics</i> 3, no.
    1 (2020). <a href="https://doi.org/10.1038/s42005-020-00491-2">https://doi.org/10.1038/s42005-020-00491-2</a>.
  ieee: 'A. N. Kosarev <i>et al.</i>, “Accurate photon echo timing by optical freezing
    of exciton dephasing and rephasing in quantum dots,” <i>Communications Physics</i>,
    vol. 3, no. 1, Art. no. 228, 2020, doi: <a href="https://doi.org/10.1038/s42005-020-00491-2">10.1038/s42005-020-00491-2</a>.'
  mla: Kosarev, Alexander N., et al. “Accurate Photon Echo Timing by Optical Freezing
    of Exciton Dephasing and Rephasing in Quantum Dots.” <i>Communications Physics</i>,
    vol. 3, no. 1, 228, 2020, doi:<a href="https://doi.org/10.1038/s42005-020-00491-2">10.1038/s42005-020-00491-2</a>.
  short: A.N. Kosarev, H. Rose, S.V. Poltavtsev, M. Reichelt, C. Schneider, M. Kamp,
    S. Höfling, M. Bayer, T. Meier, I.A. Akimov, Communications Physics 3 (2020).
date_created: 2020-12-16T14:30:57Z
date_updated: 2023-04-21T11:22:13Z
department:
- _id: '15'
- _id: '170'
- _id: '293'
- _id: '623'
- _id: '230'
- _id: '35'
doi: 10.1038/s42005-020-00491-2
intvolume: '         3'
issue: '1'
language:
- iso: eng
project:
- _id: '53'
  name: TRR 142
- _id: '54'
  name: TRR 142 - Project Area A
- _id: '59'
  name: TRR 142 - Subproject A2
publication: Communications Physics
publication_identifier:
  issn:
  - 2399-3650
publication_status: published
status: public
title: Accurate photon echo timing by optical freezing of exciton dephasing and rephasing
  in quantum dots
type: journal_article
user_id: '16199'
volume: 3
year: '2020'
...