Quantum Mechanics Mysteries: Reality, Observer, Prediction, Collapse, and Correlated States (original) (raw)
Related papers
2021
How come such a successful theory like Quantum Mechanics has so many mysteries? The history of this theory is replete with dubious interpretations and controversies. The knowledge of its predictions, however, caused the amazing technological revolution of the last hundred years. In its very beginning Einstein pointed out that there was something missing due to contradictions with the relativity theory. So, even though Quantum Mechanics explains all the physical phenomena, due to its mysteries, there were many attempts to find a way to “complete” it, e.g. hidden-variable theories. In this paper, we present these mysteries, with special attention to the concepts of physical reality imposed by quantum mechanics, the role of the observer, prediction limits, definition of collapse, and how to deal with correlated states (the basic strategy for quantum computers and quantum teleportation). The discussion is carried out by accepting that there is nothing important missing. We are just rest...
Demystifying Quantum Mechanics
2021
How come such a successful theory like Quantum Mechanics has so many mysteries? The history of this theory is replete with dubious interpretations and controversies. The knowledge of its predictions, however, caused the amazing technological revolution of the last hundred years. In its very beginning Einstein pointed out that there was something missing due to contradictions with the relativity theory. So, even though Quantum Mechanics explains all the physical phenomena, due to its mysteries, there were many attempts to find a way to ``complete" it, e.g. hidden-variable theories. In this paper, we discuss some of these mysteries, with special attention to the concepts of physical reality imposed by quantum mechanics, the role of the observer, prediction limits, definition of collapse, and how to deal with correlated states (the basic strategy for quantum computers and quantum teleportation). The discussion is carried out by accepting that there is nothing important missing. We...
American Journal of Physics, 1979
We reformulate the problem of the "interpretation of quantum mechanics" as the problem of DERIVING the quantum mechanical formalism from a set of simple physical postulates. We suggest that the common unease with taking quantum mechanics as a fundamental description of nature could derive from the use of an incorrect notion, as the unease with the Lorentz transformations before Einstein derived from the notion of observer independent time. Following an an analysis of the measurement process as seen by different observers, we propose a reformulation of quantum mechanics in terms of INFORMATION THEORY. We propose three different postulates out of which the formalism of the theory can be reconstructed; these are based on the notion of information about each other that systems contain. All systems are assumed to be equivalent: no observer-observed distinction, and information is interpreted as correlation. We then suggest that the incorrect notion that generates the unease with quantum mechanichs is the notion of OBSERVER INDEPENDENT state of a system.
Do we really understand quantum mechanics? Strange correlations, paradoxes, and theorems
American Journal of Physics, 2001
This article presents a general discussion of several aspects of our present understanding of quantum mechanics. The emphasis is put on the very special correlations that this theory makes possible: they are forbidden by very general arguments based on realism and local causality. In fact, these correlations are completely impossible in any circumstance, except the very special situations designed by physicists especially to observe these purely quantum effects. Another general point that is emphasized is the necessity for the theory to predict the emergence of a single result in a single realization of an experiment. For this purpose, orthodox quantum mechanics introduces a special postulate: the reduction of the state vector, which comes in addition to the Schrödinger evolution postulate. Nevertheless, the presence in parallel of two evolution processes of the same object (the state vector) may be a potential source for conflicts; various attitudes that are possible to avoid this problem are discussed in this text. After a brief historical introduction, recalling how the very special status of the state vector has emerged in quantum mechanics, various conceptual difficulties are introduced and discussed. The Einstein Podolsky Rosen (EPR) theorem is presented with the help of a botanical parable, in a way that emphasizes how deeply the EPR reasoning is rooted into what is often called "scientific method". In another section the GHZ argument, the Hardy impossibilities, as well as the BKS theorem are introduced in simple terms. The final two sections attempt to give a summary of the present situation: one section discusses non-locality and entanglement as we see it presently, with brief mention of recent experiments; the last section contains a (non-exhaustive) list of various attitudes that are found among physicists, and that are helpful to alleviate the conceptual difficulties of quantum mechanics.
Foundations of Quantum Computing (I. Demystifying Quantum Paradoxes)
SSRN Electronic Journal, 2021
Speedy developments in Quantum Technologies and Computing with far reaching potential applications in non-traditional fields of finance, bio-medical, biochemistry , etc., make it imperative that fundamentals of Quantum Technologies are well explained and understood. Meanwhile, paradigms of so-called quantum non-locality, wave function (WF) "collapse", "Schrödinger cat" and some other historically popular misconceptions continue to stir controversies, feed mysteries around quantum phenomena and confuse prospective users. In this regard we argue that above misinterpretations stem essentially from classically minded and experimentally unverifiable perceptions, recasting and fitting the Principle of Superposition and key experimental details into classical terms and logic. Further, we revisit key components of general quantum measurement protocols-analyzers and detectors-and explain in this context paradoxes of WF collapse and Schrödinger cat. Then to demystify and clarify the concept of entanglement in multi-component systems (comprised of photons, electrons, atoms and even small macro-objects) and longdistance correlations, we remind that quantum measurements routinely reveal correlations mandated by conservation laws in each individual realization. Remarkably, this "correlation-by-initial conditions" (in addition to traditional "correlation-byinteractions") is by no means an exclusive quantum feature, but also has it analogiesin simplified form though-in Classical Mechanics (CM). However, an appearance and understanding of those correlations in Quantum Mechanics (QM) is governed by the wave-particle duality, forgetting of which leads to endless line of paradoxes. We keep reiterating that QM is not a dynamical theory in the same sense the CM is-it is a statistical theory, as established in 1926 by Born's postulate. That is, while QM enforces conservations laws and ensuing correlations in each individual outcome, it does not indicate how exactly a specific outcome is selected. This selection remains fundamentally random and represents true randomness of QM, the latter being a statistical paradigm with a WF standing for a complex-valued amplitude of a distribution function. We note in conclusion that, although a quantum logic is admittedly a challenge for classical imagination, mechanistically complementing quantum foundations by classically minded expectations trivializes true quantum effects to primitive classical constructions and gives rise to a mysteriously omnipresent non-locality.
What quantum mechanics is trying to tell us
American Journal of Physics, 2000
This article presents a novel interpretation of quantum mechanics. It extends the meaning of "measurement" to include all property-indicating facts. Intrinsically space is undifferentiated: there are no points on which a world of locally instantiated physical properties could be built. Instead, reality is built on facts, in the sense that the properties of things are extrinsic, or supervenient on property-indicating facts. The actual extent to which the world is spatially and temporally differentiated (that is, the extent to which spatiotemporal relations and distinctions are warranted by the facts) is necessarily limited. Notwithstanding that the state vector does nothing but assign probabilities, quantum mechanics affords a complete understanding of the actual world. If there is anything that is incomplete, it is the actual world, but its incompleteness exists only in relation to a conceptual framework that is more detailed than the actual world. Two deep-seated misconceptions are responsible for the interpretational difficulties associated with quantum mechanics: the notion that the spatial and temporal aspects of the world are adequately represented by sets with the cardinality of the real numbers, and the notion of an instantaneous state that evolves in time. The latter is an unwarranted (in fact, incoherent) projection of our apparent "motion in time" into the world of physics. Equally unwarranted, at bottom, is the use of causal concepts. There nevertheless exists a "classical" domain in which language suggestive of nomological necessity may be used. Quantum mechanics not only is strictly consistent with the existence of this domain but also presupposes it in several ways.
Quantum computation and hidden variables
2008
Many physicists limit oneself to an instrumentalist description of quantum phenomena and ignore the problems of foundation and interpretation of quantum mechanics. This instrumentalist approach results to "specialization barbarism" and mass delusion concerning the problem, how a quantum computer can be made. The idea of quantum computation can be described within the limits of quantum formalism. But in order to understand how this idea can be put into practice one should realize the question: "What could the quantum formalism describe?", in spite of the absence of an universally recognized answer. Only a realization of this question and the undecided problem of quantum foundations allows to see in which quantum systems the superposition and EPR correlation could be expected. Because of the "specialization barbarism" many authors are sure that Bell proved full impossibility of any hidden-variables interpretation. Therefore it is important to emphasize that in reality Bell has restricted to validity limits of the no-hiddenvariables proof and has shown that two-state quantum system can be described by hidden variables. The later means that no experimental result obtained on two-state quantum system can prove the existence of superposition and violation of the realism. One should not assume before unambiguous experimental evidence that any two-state quantum system is quantum bit. No experimental evidence of superposition of macroscopically distinct quantum states and of a quantum bit on base of superconductor structure was obtained for the present. Moreover same experimental results can not be described in the limits of the quantum formalism.
Interpreting the Quantum World
American Journal of Physics, 1998
The object of this book is the physical interpretation of the abstract formalism of quantum theory. This issue has been controversial from the early days of quantum mechanics, more than 70 years ago. Many of the best minds struggled with this problem, only to reach conicting conclusions. Obviously, there is no similar interpretation problem for classical mechanics, because the mathematical symbols that appear in the latter simply coincide with experimentally observable quantities. On the other hand, the quantum formalism is based on a complex vector space in which the dynamical evolution is generated by unitary operators. Everyone agrees on how to manipulate the mathematical symbols; the thorny problem is to relate them to the observable physical reality. The traditional answer is to introduce`observers' who sense the quantum world by interacting with it. While they are engaged in that interaction, the observers must obey quantum dynamics|this is needed for consistency of the formalism. Yet, after completion of the measuring process, the same observers must begiven a mundane, classical, objective description, so that the`quantum measurement' ends with a denite result, as we experience in everyday's life. Quantum mechanics itself does not predict, in general, that result. It predicts only probabilities for the various possible outcomes of a measurement, once we specify the procedure used for the preparation of the physical system. This ad hoc approach is sucient for the purposes of experimental physics, and it can even be rationalized by some theoretical physicists (including the author of this review). However, it is considered as unacceptable by philosophers of science. Bub's bookgave me an opportunity to understand why. Bub's goal is to liberate the quantum world from its dependence on observers. Various possibilities are carefully examined. The book contains an amazing wealth of information, including numerous excerpts of correspondence between Einstein, Schr odinger, Pauli, Born, and others. I h a v e particularly been impressed by the two long chapters (75 pages) which analyze in exhaustive detail the celebrated`no go' theorems of Bell and of Kochen and Specker, namely the contradictions that would arise in any attempt to supplement the