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Cited by 1,777Quantum Information and CryptographyQuantum Mechanics and ApplicationsQuantum optics and atomic interactions

Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolsky-Rosen Channels

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Boschi, D., Branca, S., De Martini, F., Hardy, L., Popescu, S.·1998·Physical Review Letters
DOI 10.1103/physrevlett.80.1121
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Abstract

We report on a quantum optical experimental implementation of teleportation of unknown pure quantum states. This realizes all of the nonlocal aspects of the original scheme proposed by Bennett et al. and is equivalent to it up to a local operation. We exhibit results for the teleportation of a linearly polarized state and of an elliptically polarized state. We show that the experimental results cannot be explained in terms of a classical channel alone. The Bell measurement in our experiment can distinguish between all four Bell states simultaneously allowing, in the ideal case, a 100% success rate of teleportation.

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Written from the paper’s full text.

TL;DR

The paper reports a quantum optical experiment that teleports unknown pure polarization states using two photons, with Einstein-Podolsky-Rosen entanglement encoded in k-vector/path and classical information sent from Alice to Bob. It demonstrates teleportation of linear and elliptical polarization states and shows the results cannot be explained by a classical channel alone.

Key findings

  • The experiment realizes all nonlocal aspects of the original Bennett et al. teleportation scheme and is equivalent to it up to a local operation.
  • For three equally spaced linear polarizations (0°, +120°, −120°), the measured average exceeded the classical teleportation limit of 3/4, violating it by 9 standard deviations.
  • For a linear state at θ = 22.5°, the coincidence maxima displacements were 22.5°, 67.5°, 112.5°, and −22.5°, consistent with the expected teleportation relations.
  • For an elliptically polarized state prepared with θ = 0 and a quarter wave plate at γ = 20°, the verification results showed the state after Bob’s quarter wave plate was vertically or horizontally polarized as required.

Methods

  • Polarization-entangled photon pairs were created by type II degenerate parametric downconversion, pumped by a 200 mW UV cw argon laser at 351.1 nm, with downconverted photons at 702.2 nm; calcite crystals converted the polarization entanglement into k-vector/path entanglement.
  • Alice performed a Bell-state measurement using a 50:50 beamsplitter, polarizers, and detectors; Bob verified the teleported state using polarization analysis with Fresnel rhomb devices, a polarizing beamsplitter, detectors, and quarter wave plates for the elliptical case.
  • The analysis compared measured coincidence counts to the classical teleportation bound, averaging over the three equally spaced linear polarizations and the four possible Bell-state outcomes.

Limitations

  • The paper states that the preparer must prepare the unknown state on one of the EPR photons, so the unknown state cannot come from outside; the scheme is equivalent to the original only up to a local operation.
  • The paper states that the required unitary transformations were implemented passively by reorienting the verification apparatus; active implementation using fast Pockel cells and polarizing beamsplitters for 100% efficiency is left as future work.
  • The paper notes that no experiment is perfect and that wide filters (Δλ = 20 nm) were used to keep count rates high enough to minimize phase drift, which is an evident trade-off in spectral selectivity.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1103/physrevlett.80.1121

Cites

12 of 12 references verified0 citation errors · 0 not checkable

Statistics

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Claims the paper makes

0 of 3 cited sources checked · 0 supported · 0 flagged

  • Findingown data
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    The paper reports a quantum optical experimental implementation of teleportation of unknown pure quantum states.

    “We report on a quantum optical experimental implementation of teleportation of unknown pure quantum states.”
    Quote in the paperSubstantial claim
  • Findingown data
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    The measured average quantity violated the classical teleportation limit by 9 standard deviations.

    “This represents a violation of the classical teleportation limit by 9 standard deviations.”
    Quote in the paperSubstantial claim
  • Premisecitation
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    In three-photon schemes where the Bell measurement is made on two photons, feasible schemes can have only a 50% rate of success even in the ideal case.

    “indeed, in three photon schemes, where the Bell measurement is made on two photons, feasible schemes can have only a 50% rate of success even in the ideal case [3]”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [3] [3] H. Weinfurter, Europhys. Lett. 559 (1994); S. L. Braunstein and A. Mann, Phys. Rev. A 51 , R1727 (19955); K. Mattle, H. weinfurter, P. G. Kwiat and A. Zeilinger, PRL 76 , 4656 (1996).

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Interpretationreasoning
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    The two-photon approach places a restriction that the preparer must prepare his state on one of the EPR photons, so the unknown state cannot come from outside.

    “However, this approach does place a restriction on us in that the preparer must prepare his state on one of the EPR photons, and so the unknown state cannot come from outside.”
    Quote in the paperSubstantial claim
  • Interpretationreasoning
    § Appendix

    The maximum of T_l is 9/8.

    “By varying with respect to the vectors | φ c l 〉 and | Ω l 〉 we obtain T max l = 9 8 .”
    Quote in the paperNot a substantial claim
  • May combine two claims. 4
  • The quote only partly states this claim. 1
  • Classified as probably not a substantial claim. 2

  • May combine two claims.

    Findingown data
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    For a linear polarised state at θ = 22.5°, the displacements of the maxima in coincidence count rates between Alice's Bell state outcomes and Bob's detector are 22.5°, 67.5°, 112.5° and -22.5°, consistent with equation (11).

    “Note that the displacements of the maxima are 22.5 ◦ , 67.5 ◦ , 112.5 ◦ and -22.5 ◦ . These are consistent with equation (11) where α = sin( θ ) and β = cos( θ ).”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Findingown data
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    For an elliptically polarised state prepared with θ = 0 and quarter wave plates at γ = 20°, the results demonstrate that the state after the quarter wave plate at Bob's end is vertically or horizontally polarised as required.

    “The results, shown in fig. 3, demonstrate that the state after the quarter wave plate is vertically or horizontally polarised as required.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    The implementation realizes all the nonlocal aspects of the original Bennett et al. teleportation scheme and is equivalent to it up to a local operation.

    “This realizes all the nonlocal aspects of the original scheme proposed by Bennett et al. and is equivalent to it up to a local operation.”
    • Also stated in: § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels · hedged
      “Nevertheless, the scheme to be described here realizes all the nonlocal aspects of the original teleportation scheme, and is equivalent to the original scheme upto a local operation (since, in principle, the unknown state of a particle from outside could be swapped onto the polarisation degree of freedom of Alice's EPR particle by a local unitary operation).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] [1] C. Bennett, G. Brassard, C. Crepeau, R. Jozsa, A. Peres and W. Wootters, Phys. Rev. Lett. 70 , 1895 (1993).

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Interpretationnone given
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    If the preparer does not tell Alice what state he has prepared, there is no way Alice can find out what the state is.

    “In particular, as in the original scheme, we emphasize that if the preparer does not tell Alice what state he has prepared then there is no way Alice can find out what the state is.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    The two-photon approach avoids difficulties associated with three photons and makes the Bell measurement much more straightforward.

    “This avoids the difficulties associated with having three photons and, as will be seen below, makes the Bell measurement much more straight forward”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    The classical teleportation protocol must satisfy S ≤ 3/4, so the average probability of passing the test cannot exceed 3/4.

    “To beat the classical teleportation limit the average value of this quantity must exceed 3 / 4.”
    • Also stated in: § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels · plain
      “In the appendix we show this classical teleportation protocol must satisfy”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning
    § Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels

    Wide filters were used so that the count rate was high enough to allow measurements in a few seconds in order to minimize problems associated with phase drift.

    “Wide, rather than narrow, filters were used so that the count rate was high enough to allow measurements to be made in a few seconds in order that problems associated with phase drift were minimize.”
    Quote in the paperNot a substantial claim
7 of 7

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • A protocol of the emulation kind was proposed by Popescu (1995) and experimentally realized in Rome (Boschi et al., 1998) with a teleportation fidelity of 0.85(1).

    “A protocol of this kind has been proposed by Popescu (1995) and was experimentally realized in Rome (Boschi et al., 1998) with a teleportation fidelity of 0.85 (1).”

    From Multiphoton entanglement and interferometry (2012) · cites this paper as Boschi et al., 1998

    The main text (page unavailable) says the Rome experiment used a two-photon approach first suggested by Popescu and reports teleportation results that exceeded the classical limit. However, the measured value appears only in a formula that is not decoded in our copy, so the stated fidelity of 0.85(1) cannot be verified. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • There is no possibility of varying the intrinsic degree of entanglement ε to produce non-maximally entangled states without compromising the purity of the state (introducing mixture).

    “There is no possibility of varying the intrinsic degree of entanglement , ε [11], to produce non-maximally entangled states without compromising the purity of the state, i.e., introducing mixture [12].”

    From Nonmaximally Entangled States: Production, Characterization, and Utilization (1999) · cites this paper as [11]

    The experiment description (page unavailable) discusses preparing an entangled photon pair, but does not discuss varying its intrinsic degree of entanglement. The passage on an impure teleported state explains how to adapt a measurement analysis; it does not say that producing a non-maximally entangled state necessarily introduces mixture. Searches for non-maximal entanglement and purity found no passage establishing the claimed constraint. (LLM, conf=0.76)

    Experimental — accuracy not yet measured

  • For 150-mW pump power, this implies a coincidence rate of 21,000 s−1, a ×10 increase over the previous type-II source, which used a BBO crystal 2.5 times longer.

    “For 150-mW pump power, this implies a coincidence rate of 21,000s -1 [22], a × 10 increase over the previous typeII source (which used a BBO crystal 2.5 times longer [12]).”

    From Ultrabright source of polarization-entangled photons (1999) · cites this paper as [22]

  • Such brightness is completely necessary for some applications, like quantum cryptography to a satellite, and very advantageous for others, like teleportation, which requires two pairs of entangled photons and hence scales as the square of the source intensity.

    “Such brightness is completely necessary for some applications (like quantum cryptography to a satellite), and very advantageous for others (like teleportation, which requires two pairs of entangled photons, and hence scales as the square of the source intensity).”

    From Ultrabright source of polarization-entangled photons (1999) · cites this paper as [22]

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Authors
Boschi, D., Branca, S., De Martini, F., Hardy, L., & Popescu, S.
Affiliations
  • Istituto Nazionale di Fisica Nucleare (IT)
  • Isaac Newton Institute for Mathematical Sciences (GB)
ORCID
Venue
Physical Review Letters
Publisher
American Physical Society (APS)
Published
1998-02-09
Volume
80
Issue
6
Pages
1121-1125
ISSN
  • 0031-9007 (ISSN-L)
  • 1079-7114
DOI
10.1103/physrevlett.80.1121
OpenAlex
W2113730801
Semantic Scholar
1d5b60449613be61af38d9d2515cc90701a3bb31
Cited by
1,777
References
12
Citations by year
2026: 32 · 2025: 58 · 2024: 48 · 2023: 123 · 2022: 61 · 2021: 61 · 2020: 59 · 2019: 52 · 2018: 39 · 2017: 41 · 2016: 55 · 2015: 51 · 2014: 51 · 2013: 52 · 2012: 47
FWCI
109.58
Type
journal article
Language
en
Open access
Licence
link.aps.org/licenses/aps-default-license (vor)
Locations
  • Physical Review Letters (publishedVersion)
  • Bristol Research (University of Bristol) (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • CERN Document Server (European Organization for Nuclear Research) (submittedVersion)
  • arXiv (Cornell University)
Topics
  • Physical Sciences › Computer Science › Artificial Intelligence › Quantum Information and Cryptography
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Quantum Mechanics and Applications
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Quantum optics and atomic interactions
Keywords
quantum teleportation, Einstein-Podolsky-Rosen states, Bell states, Bell measurement, classical channels, polarization state, linear polarization, elliptical polarization, quantum nonlocality

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