arXiv subjects

Caroline H. Thompson

Publications and source records attributed to Caroline H. Thompson.

5 recordsLinked to original sources

arXiv2005

The "Chaotic Ball" model,local realism and the Bell test loopholes

It has long been known that the "detection loophole", present when detector efficiencies are below a critical figure, could open the way for alternative "local realist" explanations for the violation of Bell tests. It has in recent years become common to assume the loophole can be ignored, regardless of which version of the Bell test is employed. A simple model is presented that illustrates that this may not be justified. Two of the versions -- the standard test of form -2 <= S <= 2 and the currently-popular "visibility" test -- are at grave risk of bias. Statements implying that experimental evidence "refutes local realism" or shows that the quantum world really is "weird" should be reviewed. The detection loophole is on its own unlikely to account for more than one or two test violations, but when taken in conjunction with other loopholes (briefly discussed) it is seen that the experiments refute only a narrow class of "local hidden variable" models, applicable to idealised situations, not to the real world. The full class of local realist models provides straightforward explanations not only for the publicised Bell-test violations but also for some lesser-known "anomalies".

quant-ph↗

arXiv2004

The Chaotic Ball: An Intuitive Analogy for EPR Experiments

Actual realisations of EPR experiments do {\em not} demonstrate non-locality. A model is presented that should enable non-specialists as well as specialists to understand how easy it is to find realistic explanations for the observations. The model also suggests new areas where realistic (``hidden-variable'') models can give valid predictions whilst quantum mechanics fails. It offers straightforward explanations for some anomalies that Aspect was unable to account for, providing perhaps the first experimental evidence that a hidden-variable theory can be {\em superior} to quantum mechanics. The apparent success of quantum mechanics in predicting results is shown to be largely due to the use of unjustifiable and biased analysis of the data. Data that has been discarded because it did not lead to a valid Bell's test may give further evidence that hidden variables exist.

quant-ph↗

arXiv1999

Subtraction of ``accidentals'' and the validity of Bell tests

In some key Bell experiments, including two of the well-known ones by Alain Aspect, 1981-2, it is only after the subtraction of ``accidentals'' from the coincidence counts that we get violations of Bell tests. The data adjustment, producing increases of up to 60% in the test statistics, has never been adequately justified. Few published experiments give sufficient information for the reader to make a fair assessment. There is a straightforward and well known realist model that fits the unadjusted data very well. In this paper, the logic of this realist model and the reasoning used by experimenters in justification of the data adjustment are discussed. It is concluded that the evidence from all Bell experiments is in urgent need of re-assessment, in the light of all the known ``loopholes''. Invalid Bell tests have frequently been used, neglecting improved ones derived by Clauser and Horne in 1974. ``Local causal'' explanations for the observations have been wrongfully neglected.

quant-ph↗

arXiv1997

Timing, ``Accidentals'' and Other Artifacts in EPR Experiments

Subtraction of ``accidentals'' in Einstein-Podolsky-Rosen experiments frequently changes results compatible with local realism into ones that appear to demonstrate non-locality. The validity of the procedure depends on the unproven assumption of the independence of emission events. Other possible sources of bias include enhancement, imperfect synchronisation, over-reliance on rotational invariance, and the well-known detection loophole. Investigation of existing results may be more fruitful than attempts at loophole-free Bell tests, improving our understanding of light.

quant-ph↗

arXiv1997

Timing and Other Artifacts in EPR Experiments

Re-evaluation of the evidence (some of it unpublished) shows that experimenters conducting Einstein-Podolsky-Bohm (EPR) experiments may have been deceived by various pre-conceptions and artifacts. False or unproven assumptions were made regarding, in some cases, fair sampling, in others timing, accidental coincidences and enhancement. Realist possibilities, assuming a purely wave model of light, are presented heuristically, and suggestions given for fruitful lines of research. Quantum Mechanics can be proved false, but Bell tests have turned out to be unsuitable for the task.

quant-ph↗