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Photon-number entanglement generated by sequential excitation of a two-level atom

Nature Photonics volume 16, pages 374–379 (2022)Cite this article

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Abstract

Entanglement and spontaneous emission are fundamental quantum phenomena that drive many applications of quantum physics. During the spontaneous emission of light from an excited two-level atom, the atom briefly becomes entangled with the photonic field. Here we show that this natural process can be used to produce photon-number entangled states of light distributed in time. By exciting a quantum dot—an artificial two-level atom—with two sequential π-pulses, we generate a photon-number Bell state. We characterize this state using time-resolved intensity and phase correlation measurements. Furthermore, we theoretically show that applying longer sequences of pulses to a two-level atom can produce a series of multi-temporal mode entangled states with properties intrinsically related to the Fibonacci sequence. Our results on photon-number entanglement can be further exploited to generate new states of quantum light with applications in quantum technologies.

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Fig. 1: Generation of photon-number Bell states.
Fig. 2: Characterization of intensity.
Fig. 3: Characterization of coherence.

Data availability

The experimental data that support the findings of this study are available in figshare at https://doi.org/10.6084/m9.figshare.16838248.

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Acknowledgements

P.S. acknowledges support from the ERC PoC PhoW, the IAD—ANR support ASTRID programme project (grant. no. ANR-18-ASTR-0024 LIGHT), the QuantERA ERA-NET Cofund in Quantum Technologies (project HIPHOP), the FET OPEN QLUSTER, and the French RENATECH network, a public grant overseen by the French National Research Agency (ANR) as part of the Investissements d’Avenir programme (Labex NanoSaclay, grant no. ANR-10-LABX-0035). J.C.L. acknowledges the Austrian Federal Ministry for Digital and Economic Affairs, the National Foundation for Research, Technology and Development, and the Christian Doppler Research Association. A.A., M.M. and S.C.W acknowledge support from the Foundational Questions Institute Fund (grant no. FQXi-IAF19-01 to A.A and S.C.W, and FQXi-IAF19-05 to A.A. and M.M.), as well as the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie (grant agreement no. 861097 to A.A., M.M. and S.C.W.). A.A. and M.M also acknowledge support from the ANR Research Collaborative Project Qu-DICE (grant no. ANR-PRC-CES47 to A.A and M.M.), the Templeton World Charity Foundation Inc (grant no. TWCF0338 to A.A. and M.M.) and the John Templeton Foundation (grant no. 61835 to A.A.). C.S. acknowledges support from the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant and Strategic Project Grant programs, as well as the National Research Council’s High-Throughput Secure Networks program. S.C.W. also acknowledges support from the NSERC Canadian Graduate Scholarships (grant nos 668347 and 677972) and the SPIE Education Scholarship program. S.C.W. and C.A.-S. acknowledge A. González-Tudela, C. Sánchez-Muñoz, T. Huber and N. Sinclair for fruitful discussions. C.A.-S. thanks K. Bencheikh and F. Raineri for providing technical assistance in the experimental set-up.

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Authors and Affiliations

  1. Institute for Quantum Science and Technology and Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada

    Stephen C. Wein & Christoph Simon

  2. Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble, France

    Stephen C. Wein, Maria Maffei & Alexia Auffèves

  3. Centre for Nanosciences and Nanotechnology, CNRS, Université Paris-Saclay, UMR 9001, Palaiseau, France

    Juan C. Loredo, Paul Hilaire, Abdelmounaim Harouri, Aristide Lemaître, Isabelle Sagnes, Loïc Lanco, Olivier Krebs, Pascale Senellart & Carlos Antón-Solanas

  4. University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), Vienna, Austria

    Juan C. Loredo

  5. Christian Doppler Laboratory for Photonic Quantum Computer, Faculty of Physics, University of Vienna, Vienna, Austria

    Juan C. Loredo

  6. Department of Physics, Virginia Tech, Blacksburg, VA, USA

    Paul Hilaire

  7. Quandela SAS, Palaiseau, France

    Niccolo Somaschi

  8. Université Paris Cité, Centre de Nanosciences et Nanotechnologies, Palaiseau, France

    Loïc Lanco

  9. Institute of Physics, Carl von Ossietzky University, Oldenburg, Germany

    Carlos Antón-Solanas

Authors
  1. Stephen C. Wein
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Contributions

The experiments were conducted by J.C.L. and C.A.-S. Data analysis was carried out by S.C.W. and C.A.-S. with help from J.C.L. and P.H. Theoretical modelling was performed by S.C.W., M.M., C.S. and A.A, with help from J.C.L and C.A.-S. Cavity devices were fabricated by A.H. and N.S. from samples grown by A.L. based on a design of L.L. Etching was performed by I.S. The manuscript was written by S.C.W. and C.A.-S. with assistance from C.S. and P.S. and input from all authors. The project was supervised by C.A.-S. with the collaboration of C.S. and P.S.

Corresponding authors

Correspondence to Stephen C. Wein or Carlos Antón-Solanas.

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Competing interests

N.S. is a co-founder—and P.S. is a scientific advisor and co-founder—of the single-photon-source company Quandela. The other authors declare no competing interests.

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Nature Photonics thanks Adam Miranowicz, Tracy Northup and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Theory derivations and the extended experimental analysis, and Supplementary Figs. 1–7.

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Wein, S.C., Loredo, J.C., Maffei, M. et al. Photon-number entanglement generated by sequential excitation of a two-level atom. Nat. Photon. 16, 374–379 (2022). https://doi.org/10.1038/s41566-022-00979-z

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