# Violation of Bell Inequalities by Photons More Than 10 km Apart

@article{Tittel1998ViolationOB,
title={Violation of Bell Inequalities by Photons More Than 10 km Apart},
author={Wolfgang Tittel and J. Brendel and Hugo Zbinden and Nicolas Gisin},
journal={Physical Review Letters},
year={1998},
volume={81},
pages={3563-3566}
}
• Published 12 June 1998
• Physics
• Physical Review Letters
A Franson-type test of Bell inequalities by photons 10.9 km apart is presented. Energy-time entangled photon pairs are measured using two-channel analyzers, leading to a violation of the inequalities by 16 standard deviations without subtracting accidental coincidences. Subtracting them, a two-photon interference visibility of 95.5% is observed, demonstrating that distances up to 10 km have no significant effect on entanglement. This sets quantum cryptography with photon pairs as a practical…
668 Citations

## Figures from this paper

Large violation of Bell inequalities using both particle and wave measurements
• Physics
2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC)
• 2011
When separated measurements on entangled quantum systems are performed, the theory predicts correlations that cannot be explained by any classical mechanism: communication is excluded because the
Bell inequalities for entangled pairs of neutral kaons
• Physics
• 1999
We extend the use of Bell-inequalities to $\Phi \to K^0 \bar{K^0}$ decays by exploiting analogies and differences to the well-known and experimentally verified singlet-spin case. Contrasting with
Space Dependence of Entangled States and Franson-type EPR Experiments
• Physics
• 2002
We analyze some aspects of recently performed Franson-type experiments with entangled photon pairs aimed to test Bell's inequalities. We point out that quantum theory leads to the coincidence rate
Loophole-free Bell test with one atom and less than one photon on average
• Physics
• 2011
We consider the entanglement between two internal states of a single atom and two photon number states describing either the vacuum or a single photon and thus containing, on average, less than one
Entanglement distribution over 300 km of fiber.
• Physics
Optics express
• 2013
The distribution of time-bin entangled photon pairs over 300 km of optical fiber is reported, confirming the violation of Bell's inequality by 2.9 standard deviations.
Free-space quantum key distribution with entangled photons
• Physics
• 2006
The authors report on a complete experimental implementation of a quantum key distribution protocol through a free-space link using polarization-entangled photon pairs from a compact parametric
Bell-inequality tests with entanglement between an atom and a coherent state in a cavity
• Physics
• 2012
We study Bell inequality tests with entanglement between a coherent-state field in a cavity and a two-level atom. In order to detect the cavity field for such a test, photon on/off measurements and
Bell-inequality violations with single photons entangled in momentum and polarization
• Physics
• 2009
We present a violation of the Clauser–Horne–Shimony–Holt and the Clauser–Horne inequalities using heralded single photons entangled in momentum and polarization modes. A Mach–Zehnder interferometer
Minimum detection efficiency for a loophole-free atom-photon bell experiment.
• Physics
Physical review letters
• 2007
It is shown that, assuming perfect detection efficiency of the atom, it is possible to perform a loophole-free atom-photon Bell experiment whenever the photodetection efficiency exceeds 0.50.

## References

SHOWING 1-10 OF 21 REFERENCES
Foundations of quantum mechanics in the light of new technology
Part 1 Proceedings of 1st Symposium, S. Kamefuchi et al: gauge fields, electromagnetism and the Bohm-Aharonov effect, C.N. Yang non-local phenomena and the Aharonov-Bohm effect, Y. Aharonov electron
Phys
• Rev. D 10, 526
• 1974
Phys
• Lett. A 232, 9
• 1997
Phys
• Lett. A228, 13 (1997); Ch. Fuchset al., Phys. Rev. A56, 1163 (1997). Actually, in these papers one assumes that the eavesdropper can measure only one qubit after the other [though see N. Gisin and I. Cirac, Phys. Lett. A229, 1
• 1997
Phys
• Rev. Lett. 69, 2881 (1992); K. Mattleet al., ibid.76, 4656
• 1996
Phys
• Lett. A200, 1
• 1995
Phys
• Rev. Lett. 28, 938 (1972); A. Aspect, P. Grangier, and G. Roger, ibid. 47, 460 (1981); Z. Y. Ou and L. Mandel, ibid. 61, 50 (1988); J. G. Rarity and P. R. Tapster, ibid. 64, 2495 (1990); J. Brendel, E. Mohler, and W. Martienssen, Europhys. Lett. 20, 575 (1992); P. Kwiat, A. M. Steinberg and R. Y.
• 1995
Phys
• Rev. Lett. 73, 1923
• 1994
Phys
• Rev. Lett. 67, 661
• 1991