arXiv:0906.5093

A Close Look at the EPR Data of Weihs et al

James H. Bigelow

Published Jun 27, 2009• 1 citation

Abstract

I examine data from EPR experiments conducted in 1997 through 1999 by Gregor Weihs and colleagues. They used detection windows of 4-6 ns to identify coincidences; I find that one obtains better results with windows 40-50 ns wide. Coincidences identified using different windows have substantially different distributions over the sixteen combinations of Alice's and Bob's measurement settings and results, which is the essence of the coincidence time loophole. However, wide and narrow window coincidences violate a Bell inequality equally strongly. The wider window yields substantially smaller violations of no-signaling conditions.

DOI: 10.48550/arxiv.0906.5093

Related papers

Is the fair sampling assumption supported by EPR experiments?

Guillaume Adenier, Andrei Yu. Khrennikov

We analyse optical EPR experimental data performed by Weihs et al in Innsbruck 1997–1998. We show that for some linear combinations of the raw coincidence rates, the experimental results display some anomalous behaviour that a more general source state (like non-maximally entangled state) cannot straightforwardly account for. We attempt to explain these anomalies by taking account of the relative efficiencies of the four channels. For this purpose, we use the fair sampling assumption, and assume explicitly that the detection efficiencies for the pairs of entangled photons can be written as a product of the two corresponding detection efficiencies for the single photons. We show that this explicit use of fair sampling cannot be maintained to be a reasonable assumption as it leads to an apparent violation of the no-signalling principle.

arXiv:quant-ph/0606122Journal of Physics B Atomic Molecular and Optical PhysicsDec 19, 2006118 citations

Analysis of coincidence-time loopholes in experimental Bell tests

Bradley Christensen, Alexander D. Hill, Paul G. Kwiat +6 more

We apply a distance-based Bell-test analysis method [E. Knill et al., Phys. Rev. A 91, 032105 (2015)] to three experimental data sets where conventional analyses failed or required additional assumptions. The first is produced from a classical source exploiting a ``coincidence-time loophole'' for which standard analysis falsely shows a Bell violation. The second is from a source previously shown to violate a Bell inequality; the distance-based analysis agrees with the previous results but with fewer assumptions. The third data set does not show a violation with standard analysis despite the high source quality, but is shown to have a strong violation with the distance-based analysis method.

arXiv:1503.07573Physical Review ASep 28, 201512 citations

Event-Based and LHV Simulation of an EPR-B Experiment: EPR-Simple and EPR-Clocked

Richard David Gill

In this note, I analyze the code and the data generated by M. Fodje's (2013) simulation programs "epr-simple" and "epr-clocked". They were written in Python published on Github only, initially without any documentation at all of how they worked. Inspection of the code showed that they made use of the detection-loophole and the coincidence-loophole respectively. I evaluate them with appropriate modified Bell-CHSH type inequalities: the Larsson detection-loophole adjusted CHSH, and the Larsson-Gill coincidence-loophole adjusted CHSH (NB: its correctness is conjecture, we do not have proof). The experimental efficiencies turn out to be approximately eta = 81% (close to optimal) and gamma = 55% (far from optimal). The observed values of CHSH are, as they should be, within the appropriately adjusted bounds. Fodjes' detection-loophole model turns out to be very, very close to Pearle's famous 1970 model, so the efficiency is close to optimal. The model has the same defect as Pearle's: the joint detection rates exhibit signaling. The coincidence-loophole model is actually a clever modification of the detection-loophole model. Because of this, however, it cannot lead to optimal efficiency. Later versions of the programs included an explanation of how they worked, including formulas, though still no reference whatever to the literature on the two loopholes which Fodje exploits, not even to the concept of an experimental (i.e., in principle, avoidable) loophole. The documentation available now does make a lot of the "reverse engineering" in this paper superfluous. I plan to incorporate its results in a new paper with a wider focus.

Jan 5, 20200 citations

Event-Based and LHV Simulation of an EPR-B Experiment: EPR-Simple and EPR-Clocked

Richard David Gill

In this note, I analyze the data generated by M. Fodje's (2013) simulation programs "epr-simple" and "epr-clocked". They were written in Python and published on Github. Inspection of the program descriptions shows that they make use of the detection-loophole and the coincidence-loophole respectively. I evaluate them with appropriate modified Bell-CHSH type inequalities: the Larsson detection-loophole adjusted CHSH, and the Larsson-Gill coincidence-loophole adjusted CHSH (NB: its correctness is conjecture, we do not have proof). The experimental efficiencies turn out to be approximately eta = 81% (close to optimal) and gamma = 55% (far from optimal). The observed values of CHSH are, as they should be, within the appropriately adjusted bounds. Fodjes' detection-loophole model turns out to be very, very close to Pearle's famous 1970 model, so the efficiency is close to optimal. The model has the same defect as Pearle's: the joint detection rates exhibit signaling. Fodje's coincidence-loophole model is actually a clever modification of his detection-loophole model. Because of this, however, it cannot lead to optimal efficiency.

Apr 15, 20210 citations

Event-Based and LHV Simulation of an EPR-B Experiment: EPR-Simple and EPR-Clocked

Richard David Gill

Apr 12, 20210 citations

Data analysis of Einstein-Podolsky-Rosen-Bohm laboratory experiments

Hans A. De Raedt, F. Jin, K. Michielsen

Data sets produced by three different Einstein-Podolsky-Rosen-Bohm (EPRB) experiments are tested against the hypothesis that the statistics of this data is described by quantum theory. Although these experiments generate data that violate Bell inequalities for suitable choices of the time-coincidence window, the analysis shows that it is highly unlikely that these data sets are compatible with the quantum theoretical description of the EPRB experiment, suggesting that the popular statements that EPRB experiments agree with quantum theory lack a solid scientific basis and that more precise experiments are called for.

arXiv:1312.6361Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIEOct 1, 201321 citations