May 4, 1998 · We experimentally entangle freely propagating particles that never physically interacted with one another or which have never been dynamically coupled by any other means. This demonstrates that quantum entanglement requires the entangled particles neither to come from a common source nor to have interacted in the past. In our experiment we take two pairs of polarization entangled photons and ... ... According to the entanglement swapping scheme, upon projection of photons 2 and 3 into the jC2l 23 state, photons 1 and 4 should be projected into the jC2l 14 state. To verify that this entangled state is obtained, we have to analyze the polarization correlations between photons 1 and 4 conditioned on coincidences between the detectors ... 1.5.2. Experimental Entanglement Swapping: Entangling Photons That Never Interacted[13] We experimentally entangle freely propagating particles that never physically interacted with one another or which have never been dynamically coupled by any other means. ... Of course, the complete two-photon state including both the spatial and the spin part has to obey bosonic symmetry. Thus, the two parts have to be either both symmetric or both antisymmetric. If the spatial part of the wave function is antisymmetric, the two photons will show fermionic statistics in their spatial behavior. ... May 4, 1998 · DOI: 10.1103/PHYSREVLETT.80.3891 Corpus ID: 123669961; Experimental Entanglement Swapping: Entangling Photons That Never Interacted @article{Pan1998ExperimentalES, title={Experimental Entanglement Swapping: Entangling Photons That Never Interacted}, author={Jian-Wei Pan and Dirk Bouwmeester and Harald Weinfurter and Anton Zeilinger}, journal={Physical Review Letters}, year={1998}, volume={80 ... ... May 22, 2013 · The role of the timing and order of quantum measurements is not just a fundamental question of quantum mechanics, but also a puzzling one. Any part of a quantum system that has finished evolving can be measured immediately or saved for later, without affecting the final results, regardless of the continued evolution of the rest of the system. In addition, the nonlocality of quantum mechanics ... ... May 4, 1998 · This demonstrates that quantum entanglement requires the entangled particles neither to come from a common source nor to have interacted in the past. In our experiment we take two pairs of polarization entangled photons and subject one photon from each pair to a Bell-state measurement. ... this even holds if the “entangling” Bell-state measurement is performed after photons 0 and 3 have already been registered. Entanglement swapping was shown [5] in a previous experiment, yet the low photon-pair visibility prevented a violation of a Bell’s inequality [6] for photons 0 and 3, which is a definitive test. ... swapping [15] and multistage entanglement swapping [16], entangled photons that were separated spatially, but not temporally, i.e., all the photons that were entangled, existed and were measured at the same time. In this work we demonstrate how the time at which quantum measurements are taken and their order has no effect on the outcome of a ... ... Apr 22, 2012 · In the entanglement swapping 1,2,3 procedure, two pairs of entangled photons are produced, and one photon from each pair is sent to Victor. The two other photons from each pair are sent to Alice ... ... ">
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experimental entanglement swapping entangling photons that never interacted

Experimental Entanglement Swapping: Entangling Photons That Never Interacted

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  • Dik Bouwmeester ,
  • Harald Weinfurter ,
  • Anton Zeilinger
  • Phys.Rev.Lett. 80 (1998) 18 , 3891
  • Published: May 4, 1998
  • 10.1103/PhysRevLett.80.3891

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  • Published: 22 April 2012

Experimental delayed-choice entanglement swapping

  • Xiao-song Ma 1 , 2 ,
  • Stefan Zotter 1   nAff4 ,
  • Johannes Kofler 1   nAff4 ,
  • Rupert Ursin 1 ,
  • Thomas Jennewein 1   nAff4 ,
  • Časlav Brukner 1 , 3 &
  • Anton Zeilinger 1 , 2 , 3  

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Motivated by the question of which kind of physical interactions and processes are needed for the production of quantum entanglement, Peres has put forward the radical idea of delayed-choice entanglement swapping. There, entanglement can be ‘produced a posteriori , after the entangled particles have been measured and may no longer exist’. Here, we report the realization of Peres’s gedanken experiment. Using four photons, we can actively delay the choice of measurement—implemented through a high-speed tunable bipartite-state analyser and a quantum random-number generator—on two of the photons into the time-like future of the registration of the other two photons. This effectively projects the two already registered photons onto one of two mutually exclusive quantum states in which the photons are either entangled (quantum correlations) or separable (classical correlations). This can also be viewed as ‘quantum steering into the past’.

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Change history, 26 april 2012.

In the version of this Article originally published online, the definition of the witness operator given in the paragraph after equation (4) was incorrect. This error has been corrected in all versions of the Article.

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Acknowledgements

We are grateful to N. Tetik and A. Qarry for help during the early stages of the experiment, and M. Aspelmeyer and P. Walther for fruitful discussions. We acknowledge support from the European Commission, Q-ESSENCE (No. 248095), ERC Advanced Senior Grant (QIT4QAD) and the John Templeton Foundation, as well as SFB-FOQUS and the Doctoral Program CoQuS of the Austrian Science Fund (FWF).

Author information

Stefan Zotter, Johannes Kofler & Thomas Jennewein

Present address: Present addresses: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria (S.Z.); Max Planck Institute of Quantum Optics, Hans-Kopfermann-Str. 1, 85748 Garching/Munich, Germany (J.K.); Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, 200 University Ave W., Waterloo, Ontario, Canada N2L3G1 (T.J.),

Authors and Affiliations

Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria

Xiao-song Ma, Stefan Zotter, Johannes Kofler, Rupert Ursin, Thomas Jennewein, Časlav Brukner & Anton Zeilinger

Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria

Xiao-song Ma & Anton Zeilinger

Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria

Časlav Brukner & Anton Zeilinger

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Contributions

X-s.M. designed and carried out the experiment and analysed data. S.Z. provided experimental assistance. J.K. provided the theoretical analysis and analysed data. R.U. provided experimental and conceptual assistance. T.J. conceived the research, planned and performed the experiment and analysed data. Č.B. provided theoretical suggestions and analysis. A.Z. conceived the research, designed the experiment and supervised the project. All authors wrote the manuscript.

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Correspondence to Xiao-song Ma or Anton Zeilinger .

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Ma, Xs., Zotter, S., Kofler, J. et al. Experimental delayed-choice entanglement swapping. Nature Phys 8 , 479–484 (2012). https://doi.org/10.1038/nphys2294

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experimental entanglement swapping entangling photons that never interacted

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COMMENTS

  1. Experimental Entanglement Swapping: Entangling Photons That ...

    May 4, 1998 · We experimentally entangle freely propagating particles that never physically interacted with one another or which have never been dynamically coupled by any other means. This demonstrates that quantum entanglement requires the entangled particles neither to come from a common source nor to have interacted in the past. In our experiment we take two pairs of polarization entangled photons and ...

  2. LETTERS - UC Santa Barbara

    According to the entanglement swapping scheme, upon projection of photons 2 and 3 into the jC2l 23 state, photons 1 and 4 should be projected into the jC2l 14 state. To verify that this entangled state is obtained, we have to analyze the polarization correlations between photons 1 and 4 conditioned on coincidences between the detectors

  3. 1.5.2. Experimental Entanglement Swapping: Entangling Photons ...

    1.5.2. Experimental Entanglement Swapping: Entangling Photons That Never Interacted[13] We experimentally entangle freely propagating particles that never physically interacted with one another or which have never been dynamically coupled by any other means.

  4. Experimental Entanglement Swapping: Entangling Photons That ...

    Of course, the complete two-photon state including both the spatial and the spin part has to obey bosonic symmetry. Thus, the two parts have to be either both symmetric or both antisymmetric. If the spatial part of the wave function is antisymmetric, the two photons will show fermionic statistics in their spatial behavior.

  5. Experimental Entanglement Swapping: Entangling Photons That ...

    May 4, 1998 · DOI: 10.1103/PHYSREVLETT.80.3891 Corpus ID: 123669961; Experimental Entanglement Swapping: Entangling Photons That Never Interacted @article{Pan1998ExperimentalES, title={Experimental Entanglement Swapping: Entangling Photons That Never Interacted}, author={Jian-Wei Pan and Dirk Bouwmeester and Harald Weinfurter and Anton Zeilinger}, journal={Physical Review Letters}, year={1998}, volume={80 ...

  6. Entanglement Swapping between Photons that have Never Coexisted

    May 22, 2013 · The role of the timing and order of quantum measurements is not just a fundamental question of quantum mechanics, but also a puzzling one. Any part of a quantum system that has finished evolving can be measured immediately or saved for later, without affecting the final results, regardless of the continued evolution of the rest of the system. In addition, the nonlocality of quantum mechanics ...

  7. Experimental Entanglement Swapping: Entangling Photons That ...

    May 4, 1998 · This demonstrates that quantum entanglement requires the entangled particles neither to come from a common source nor to have interacted in the past. In our experiment we take two pairs of polarization entangled photons and subject one photon from each pair to a Bell-state measurement.

  8. Experimental Nonlocality Proof of Quantum Teleportation and

    this even holds if the “entangling” Bell-state measurement is performed after photons 0 and 3 have already been registered. Entanglement swapping was shown [5] in a previous experiment, yet the low photon-pair visibility prevented a violation of a Bell’s inequality [6] for photons 0 and 3, which is a definitive test.

  9. Entanglement Swapping between Photons that have Never Coexisted

    swapping [15] and multistage entanglement swapping [16], entangled photons that were separated spatially, but not temporally, i.e., all the photons that were entangled, existed and were measured at the same time. In this work we demonstrate how the time at which quantum measurements are taken and their order has no effect on the outcome of a ...

  10. Experimental delayed-choice entanglement swapping | Nature ...

    Apr 22, 2012 · In the entanglement swapping 1,2,3 procedure, two pairs of entangled photons are produced, and one photon from each pair is sent to Victor. The two other photons from each pair are sent to Alice ...