arXiv subjects

Marian Kupczynski

Publications and source records attributed to Marian Kupczynski.

34 records · Page 2Linked to original sources

arXiv2016

The contextuality loophole is fatal for Bell inequalities: Reply to a comment by I. Schmelzer

Ilya Schmelzer wrote recently: {\it Nieuwenhuizen argued that there exists some "contextuality loophole" in Bell's theorem. This claim in unjustified}. It is made clear that this arose from attaching a meaning to the title and the content of the paper different from the one intended by Nieuwenhuizen. "Contextual loophole" means only that if the supplementary parameters describing measuring instruments are correctly introduced, Bell and Bell-type inequalities may not be proven. It is also stressed that a hidden variable model suffers from a "contextuality loophole" if it tries to describe different sets of incompatible experiments using a unique probability space and a unique joint probability distribution.

quant-ph↗

arXiv2016

Comments on New Ontology of Quantum Mechanics called CSM

A new quantum ontology of quantum mechanics has been proposed recently. This ontology is based on impossible to realize measurements which need to be performed repeatedly on the same single physical system or on the same pair of physical systems. We agree that quantum mechanics is a contextual theory and that the experimental contexts have to be a part of any description of quantum phenomena but in our opinion this new ontology is neither convincing nor useful. In particular the authors claim that their ontology explains the peaceful coexistence between quantum mechanics and relativity in spin polarization correlation experiments. We show that, contrary to their claim, the authors are unable to explain why strong correlations, between the outcomes of distant local measurements, do exist and why they preserve a condition of parameter independence (non-signaling). Strangely enough the authors ignore that these strong but imperfect correlations can be explained in a local and causal way using statistical contextual interpretation of quantum mechanics what was demonstrated in several articles.

quant-ph↗

arXiv2016

EPR Paradox, Quantum Nonlocality and Physical Reality

Eighty years ago Einstein demonstrated that a particular interpretation of the reduction of wave function led to a paradox and that this paradox disappeared if statistical interpretation of quantum mechanics was adopted. According to the statistical interpretation a wave function describes only an ensemble of identically prepared physical systems. Searching for an intuitive explanation of long range correlations between outcomes of distant measurements, performed on pairs of physical systems prepared in a spin singlet state, John Bell analysed local realistic hidden variable models and proved that correlations consistent with these models satisfy Bell inequalities which are violated by some predictions of quantum mechanics. Several different local models were constructed, various inequalities proven and shown to be violated by experimental data. Some physicists concluded that Nature is definitely not local. We strongly disagree with this conclusion and we critically analyze some influential finite sample proofs of various inequalities and so called quantum Randi challenges. We also show how one can win so called Bell game.The violation of inequalities does not prove that local and causal explanation of correlations is impossible. The violation of inequalities gives only a strong argument against counterfactual definiteness and against a point of view according to which experimental outcomes are produced in irreducible random way. We also explain the meaning of sample homogeneity loophole and show how it can invalidate statistical significance tests. We point out that this loophole was not closed in several recent experiments testing local realism.

quant-ph↗

arXiv2016

On operational approach to entanglement and how to certify it

Entangled physical systems are an important resource in quantum information. Some authors claim that in fact all quantum states are entangled. In this paper we show that this claim is incorrect and we discuss in operational way differences existing between separable and entangled states. A sufficient condition for entanglement is the violation of Bell- CHSH-CH inequalities and/or steering inequalities. Since there exist experiments outside the domain of quantum physics violating these inequalities therefore in the operational approach one cannot say that the entanglement is an exclusive quantum phenomenon. We also explain that an unambiguous experimental certification of the entanglement is a difficult task because classical statistical significance tests may not be trusted if sample homogeneity cannot be tested or is not tested carefully enough.

quant-ph↗

arXiv2015

Breakdown of statistical inference from some random experiments

Many experiments can be interpreted in terms of random processes operating according to some internal protocols. When experiments are costly or cannot be repeated only one or a few finite samples are available. In this paper we study data generated by pseudo-random computer experiments operating according to particular internal protocols. We show that the standard statistical analysis performed on a sample, containing 100000 data points or more, may sometimes be highly misleading and statistical errors largely underestimated. Our results confirm in a dramatic way the dangers of standard asymptotic statistical inference if a sample is not homogenous. We demonstrate that analyzing various subdivisions of samples by multiple chi-square tests and chi-square frequency graphs is very effective in detecting sample inhomogeneity. Therefore to assure correctness of the statistical inference the above mentioned chi-square tests and other non-parametric sample homogeneity tests should be incorporated in any statistical analysis of experimental data. If such tests are not performed the reported conclusions and estimates of the errors cannot be trusted.

physics.data-an↗

arXiv2015

Bell Inequalities, Experimental Protocols and Contextuality

The violation of Bell, CHSH and CH inequalities indicates only that the assumption of "conterfactual definiteness" and/or the probabilistic models used in proofs were incorrect. In this paper we discuss in detail an intimate relation between experimental protocols and probabilistic models. In particular we show that local realistic and stochastic hidden variable models are inconsistent with the experimental protocols used in spin polarization correlation experiments. In particular these models neglect a contextual character of quantum theory (QT) and do not describe properly quantum measurements. We argue that the violation of various inequalities gives arguments against the irreducible randomness of act of the measurement. Therefore quantum probabilities are reducible what means that QT is emergent. In this case one could expect to discover in time series of data some unpredicted fine structures proving that QT is not predictably complete what would be a major discovery.

quant-ph↗

arXiv2015

Greeks were right : critical comments on Qbism

In this short essay we reject the interpretation of quantum theory called quantum Bayesianism (Qbism) which has been promoted recently by David Mermin in his essay published in Nature. According to Qbism quantum states are personal judgements of human agents. Physicists are not verifying their personal beliefs about their observations but search for the mathematical abstract description allowing to explain and to predict in a quantitative way the regularities observed (and those to be discovered) in physical phenomena which exist independently of the presence of any agent. We reject also the claim that Qbism explains properly the quantum nonlocality. The distant long range correlations can be correctly explained using a contextual statistical interpretation of quantum theory. We conclude that the Greeks were right to remove a perceiving subject out of Science.

quant-ph↗

arXiv2015

Significance tests and sample homogeneity loophole

In their recent comment, published in Nature, Jeffrey T.Leek and Roger D.Peng discuss how P-values are widely abused in null hypothesis significance testing . We agree completely with them and in this short comment we discuss the importance of sample homogeneity tests. No matter with how much scrutiny data are gathered if homogeneity tests are not performed the significance tests suffer from sample homogeneity loophole and the results may not be trusted. For example sample homogeneity loophole was not closed in the experiment testing local realism in which a significant violation of Eberhard inequality was found. We are not surprised that Bell type inequalities are violated since if the contextual character of quantum observables is properly taken into account these inequalities cannot be proven. However in order to trust the significance of the violation sample homogeneity loophole must be closed. Therefore we repeat after Jeffrey T.Leek and Roger D.Peng that sample homogeneity loophole is probably just the tip of the iceberg.

quant-ph↗

arXiv2013

Possible violation of the optical theorem in LHC experiments

The optical theorem allowing the determination of the total cross section for a hadron-hadron scattering from the imaginary part of the forward elastic scattering amplitude is believed to be an unavoidable consequence of the conservation of probability and of the unitary S matrix. This is a fundamental theorem which contains not directly measurable imaginary part of the forward elastic scattering amplitude. The impossibility of scattering phenomena without the elastic channel is considered to be a part of the quantum magic. However if one takes seriously the idea that the hadrons are extended particles one may define a unitary S matrix such that one cannot prove the optical theorem. Moreover data violating the optical theorem do exist but they are not conclusive due to the uncertainties related to the extrapolation of the differential elastic cross-section to the forward direction. These results were published several years ago but they were forgotten. In this paper we will recall these results in an understandable way and we will give the additional arguments why the optical theorem can be violated in high energy strong interaction scattering and why it should be tested and not simply used as a tool in LHC experiments.

hep-ph↗

arXiv2013

Causality and local determinism versus quantum nonlocality

The entanglement and the violation of Bell and CHSH inequalities in spin polarization correlation experiments (SPCE) is considered to be one of the biggest mysteries of Nature and is called quantum nonlocality. In this paper we show once again that this conclusion is based on imprecise terminology and on the lack of understanding of probabilistic models used in various proofs of Bell and CHSH theorems. These models are inconsistent with experimental protocols used in SPCE. This is the only reason why Bell and CHSH inequalities are violated. A probabilistic non-signalling description of SPCE, consistent with quantum predictions, is possible and it depends explicitly on the context of each experiment. It is also deterministic in the sense that the outcome is determined by supplementary local parameters describing both a physical signals and measuring instruments. The existence of such description gives additional arguments that quantum theory is emergent from some more detailed theory respecting causality and local determinism. If quantum theory is emergent then there exist perhaps some fine structures in time-series of experimental data which were not predicted by quantum theory. In this paper we explain how a systematic search for such fine structures can be done. If such reproducible fine structures were found it would show that quantum theory is not predictably complete what would be a major discovery.

quant-ph↗

arXiv2012

Operational approach to the entanglement

In early days of quantum theory it was believed that the results of measurements performed on two distant physical systems should be uncorrelated thus their quantum state should be separable it means described by a simple tensor product of the individual local state vectors or a tensor product of individual local density operators. It was shown many years ago by EPR that two systems which interacted in the past and separated afterwards had to be described in most cases by particular non-separable states which are called entangled. It was noticed by Zanardi et al. that a Hilbert space of possible state vectors of compound physical system could be partitioned in different way by introducing various tensor product structures induced by the experimentally accessible observables (interactions and measurements). Therefore a separable state in one partition could become entangled in different partition. In this sense the entanglement was relative to a particular set of experimental capabilities. Continuing this line of thought Torre et al. claimed to prove that for any separable state there existed strongly correlated physical observables therefore all quantum states were entangled. The same claims one may find in several recent papers. In this paper we will discuss in operational way the differences existing between separable, non-separable and entangled states and we will show that the conclusions of Torre et al. were unjustified. A sufficient condition for entanglement is the violation of BI-CHSH and/or steering inequalities. Since there exist experiments outside the quantum physics violating these inequalities therefore in the operational approach one cannot say that the entanglement is an exclusive quantum phenomenon.

quant-ph↗

arXiv2010

Time Series, Stochastic Processes and Completeness of Quantum Theory

Most of physical experiments are usually described as repeated measurements of some random variables. The experimental data registered by on-line computers form time series of outcomes. The frequencies of different outcomes are compared with the probabilities provided by the algorithms of quantum theory (QT). In spite of statistical predictions of QT a claim was made that the theory provided the most complete description of the data and of the underlying physical phenomena. This claim could be easily rejected if some fine structures, averaged out in standard statistical descriptive analysis, were found in the time series of experimental data. To search for these structures one has to use more subtle statistical tools which were developed to study time series produced by various stochastic processes. In this talk we review some of these tools. As an example we show how the standard descriptive statistical analysis of the data is unable to reveal a fine structure in a simulated sample of AR(2) stochastic process. We emphasize once again that the violation of Bell inequalities gives no information on the completeness or the non locality of QT. The appropriate way to test the completeness of quantum theory is to search for fine structures in time series of experimental data by means of the purity tests or by studying the autocorrelation and partial autocorrelation functions.

quant-ph↗

arXiv2008

Is the quantum theory predictably complete?

Quantum theory (QT) provides statistical predictions for various physical phenomena. The outcomes of these measurements are in general some numerical time series registered by some macroscopic instruments. The various empirical probability distributions extracted from these time series were shown to be consistent with the probabilistic predictions of QT. However it was not proven that the time series of existing experimental data did not contain some stochastic fine structures, which could have been averaged out by describing them in terms of the empirical probability distributions. In this paper we advocate various statistical tests which could be used to search for such fine structures in the data and to answer the title question of this paper. In our opinion a proper understanding of the statistical character of QT and of its limitations is crucial in the domains such as: quantum optics and quantum information.

quant-ph↗

arXiv2007

EPR Paradox,Locality and Completeness of Quantum Theory

The quantum theory (QT) and new stochastic approaches have no deterministic prediction for a single measurement or for a single time -series of events observed for a trapped ion, electron or any other individual physical system. The predictions of QT being of probabilistic character apply to the statistical distribution of the results obtained in various experiments. The probability distribution is not an attribute of a dice but it is a characteristic of a whole random experiment : '' rolling a dice''. and statistical long range correlations between two random variables X and Y are not a proof of any causal relation between these variable. Moreover any probabilistic model used to describe a random experiment is consistent only with a specific protocol telling how the random experiment has to be performed.In this sense the quantum theory is a statistical and contextual theory of phenomena. In this paper we discuss these important topics in some detail. Besides we discuss in historical perspective various prerequisites used in the proofs of Bell and CHSH inequalities concluding that the violation of these inequalities in spin polarization correlation experiments is neither a proof of the completeness of QT nor of its nonlocality. The question whether QT is predictably complete is still open and it should be answered by a careful and unconventional analysis of the experimental data. It is sufficient to analyze more in detail the existing experimental data by using various non-parametric purity tests and other specific statistical tools invented to study the fine structure of the time-series. The correct understanding of statistical and contextual character of QT has far reaching consequences for the quantum information and quantum computing.

quant-ph↗

arXiv2007

Seventy Years of the EPR Paradox

In spite of the fact that statistical predictions of quantum theory (QT) can only be tested if large amount of data is available a claim has been made that QT provides the most complete description of an individual physical system. Einstein's opposition to this claim and the paradox he presented in the article written together with Podolsky and Rosen in 1935 inspired generations of physicists in their quest for better understanding of QT. Seventy years after EPR article it is clear that without deep understanding of the character and limitations of QT one may not hope to find a meaningful unified theory of all physical interactions, manipulate qubits or construct a quantum computer. In this paper we present shortly the EPR paper and the discussion which followed it. By emphasizing the difference between quantum phenomena and hypothetical invisible sub phenomena we show that paradoxes are only found if incorrect models of sub phenomena are used. The violation of Bell and CHSH inequalities demonstrate clearly that "an entangled pair of photons" resembles neither "a pair of Bertlmann's socks" nor "a pair of fair and random dices". Finally we rephrase the EPR question by asking whether QT provides the complete description of experimental data.

quant-ph↗

arXiv2002

On the Completeness of Quantum Mechanics

Quantum cryptography, quantum computer project, space-time quantization program and recent computer experiments reported by Accardi and his collaborators show the importance and actuality of the discussion of the completeness of quantum mechanics (QM) started by Einstein more than 70 years ago. Many years ago we pointed out that the violation of Bell's inequalities is neither a proof of completeness of QM nor an indication of the violation of Einsteinian causality. We also indicated how and in what sense a completeness of QM might be tested with the help of statistical nonparametric purity tests. In this paper we review and refine our arguments. We also point out that the statistical predictions of QM for two-particle correlation experiments do not give any deterministic prediction for a single pair. After beam is separated we obtain two beams moving in opposite directions. If the coincidence is reported it is only after the beams had interacted with corresponding measuring devices and two particles had been detected. This fact has implications for quantum cryptography. Namely a series of the measurements performed on the beam by Bob and converted into a string of bits (secret key) will in general differ, due to lack of strict anti-correlations, from a secret key found by Alice using the same procedure.

quant-ph↗