Weekly Papers on Quantum Foundations (30)

This is a list of this week's papers on quantum foundations published in the various journals or uploaded to the preprint servers such as arxiv.org and PhilSci Archive.

Spacetime structure

ScienceDirect Publication: Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics

on 2015-7-24 11:23pm GMT

Publication date: August 2015
Source:Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics, Volume 51
Author(s): Thomas William Barrett
This paper makes an observation about the “amount of structure” that different classical and relativistic spacetimes posit. The observation substantiates a suggestion made by Earman (1989) and yields a cautionary remark concerning the scope and applicability of structural parsimony principles.

Extracting information about the initial state from the black hole radiation. (arXiv:1507.06402v1 [gr-qc])

gr-qc updates on arXiv.org

on 2015-7-24 9:08am GMT

Authors: Kinjalk LochanT. Padmanabhan

The crux of the black hole information paradox is related to the fact that the complete information about the initial state of a quantum field in a collapsing spacetime is not available to future asymptotic observers, belying the expectations from a unitary quantum theory. We study the imprints of the initial quantum state, contained in the distortions of the black hole radiation from the thermal spectrum, which can be detected by the asymptotic observers. We identify the class of in-states which can be fully reconstructed from the information contained in the distortions at the semiclassical level. Even for the general in-state, we can uncover a specific amount of information about the initial state. For a large class of initial states, some specific observables defined in the initial Hilbert space are completely determined from the resulting final spectrum. These results suggest that a \textit{classical} collapse scenario ignores this richness of information in the resulting spectrum and a consistent quantum treatment of the entire collapse process might allow us to retrieve all the information from the spectrum of the final radiation.

Heisenberg's original derivation of the uncertainty principle and its universally valid reformulations. (arXiv:1507.02010v2 [quant-ph] UPDATED)

quant-ph updates on arXiv.org

on 2015-7-24 9:07am GMT

Authors: Masanao Ozawa

Heisenberg's uncertainty principle was originally posed for the limit of the accuracy of simultaneous measurement of non-commuting observables as stating that canonically conjugate observables can be measured simultaneously only with the constraint that the product of their mean errors should be no less than a limit set by Planck's constant. However, Heisenberg with the subsequent completion by Kennard has long been credited only with a constraint for state preparation represented by the product of the standard deviations. Here, we show that Heisenberg actually proved the constraint for the accuracy of simultaneous measurement but assuming an obsolete postulate for quantum mechanics. This assumption, known as the repeatability hypothesis, formulated explicitly by von Neumann and Schr\"{o}dinger, was broadly accepted until the 1970s, but abandoned in the 1980s, when completely general quantum measurement theory was established. We also survey the author's recent proposal for a universally valid reformulation of Heisenberg's uncertainty principle under the most general assumption on quantum measurement.

Reality Without Realism: On the Ontological and Epistemological Architecture of Quantum Mechanics

Latest Results for Foundations of Physics

on 2015-7-24 12:00am GMT


First, this article considers the nature of quantum reality (the reality responsible for quantum phenomena) and the concept of realism (our ability to represent this reality) in quantum theory, in conjunction with the roles of locality, causality, and probability and statistics there. Second, it offers two interpretations of quantum mechanics, developed by the authors of this article, the second of which is also a different (from quantum mechanics) theory of quantum phenomena. Both of these interpretations are statistical. The first interpretation, by A. Plotnitsky, “the statistical Copenhagen interpretation,” is nonrealist, insofar as the description or even conception of the nature of quantum objects and processes is precluded. The second, by A. Khrennikov, is ultimately realist, because it assumes that the quantum-mechanical level of reality is underlain by a deeper level of reality, described, in a realist fashion, by a model, based in the pre-quantum classical statistical field theory, the predictions of which reproduce those of quantum mechanics. Moreover, because the continuous fields considered in this model are transformed into discrete clicks of detectors, experimental outcomes in this model depend on the context of measurement in accordance with N. Bohr’s interpretation and the statistical Copenhagen interpretation, which coincides with N. Bohr’s interpretation in this regard.

On the quantum measurement problem. (arXiv:1507.05255v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-7-21 12:33am GMT

Authors: Caslav Brukner

In this paper, I attempt a personal account of my understanding of the measurement problem in quantum mechanics, which has been largely in the tradition of the Copenhagen interpretation. I assume that (i) the quantum state is a representation of knowledge of a (real or hypothetical) observer relative to her experimental capabilities; (ii) measurements have definite outcomes in the sense that only one outcome occurs; (iii) quantum theory is universal and the irreversibility of the measurement process is only "for all practical purposes". These assumptions are analyzed within quantum theory and their consistency is tested in Deutsch's version of the Wigner's friend gedanken experiment, where the friend reveals to Wigner whether she observes a definite outcome without revealing which outcome she observes. The view that holds the coexistence of the "facts of the world" common both for Wigner and his friend runs into the problem of the hidden variable program. The solution lies in understanding that "facts" can only exist relative to the observer.

On the existence of a non-relativistic hermitian time operator. (arXiv:1507.05510v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-7-21 12:33am GMT

Authors: Carringtone KinyanjuiDismas Simiyu Wamalwa

The existence of a hermitian time operator is proposed in the framework of non-relativistic quantum mechanics.The Heisenberg equation of motion is shown to yield constant rate of flow of time.It is shown to yield results consistent with classical expectations,when Bohr's correspondence principle is invoked.Further,it is shown that a massless free particle with non-zero momentum experiences timelessness in its own frame of reference whereas a negatively massive particle perceives forwardness of time.Moreover,application to quantum harmonic oscillators shows instantaneous transition of electrons from one eigenstate to another.

Non-Integer Multiverse. (arXiv:1507.05196v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-7-21 12:33am GMT

Authors: Marvin Chester

In quantum mechanics physical processes procede by two different mechanisms. John von Neumann enumerated them as 1, the "discontinuous ... arbitrary changes by measurement," and 2, continuous evolution via the Schroedinger Equation. That the physical world does not obey a single overriding law - unitary evolution by the Schroedinger Equation - is philosophically disturbing to some. Others face it with equanimity. One narrative that preserves the findings of quantum mechanics yet does produce pure unitary evolution is that of the multiverse. Given below is the narrative by which Born's Rule emerges without pre-assigning to it the notion of probability. It requires that the number of universes in the multiverse not be enumerable!

Quantum Communication. (arXiv:1507.05157v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-7-21 12:33am GMT

Authors: Nicolas Gisin

Quantum Communication is the art of transferring an unknown quantum state from one location, Alice, to a distant one, Bob. This is a non-trivial task because of the quantum no-cloning theorem which prevents one from merely using only classical means.

A Stronger Bell Argument for Quantum Non-Locality

PhilSci-Archive: No conditions. Results ordered -Date Deposited.

on 2015-7-19 4:53pm GMT

Näger, Paul M (2015) A Stronger Bell Argument for Quantum Non-Locality. [Preprint]

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