Weekly Papers on Quantum Foundations (8)

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

Do Renormalization Group Explanations Conform to the Commonality Strategy?

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

on 2016-2-19 6:09am GMT

Reutlinger, Alexander (2016) Do Renormalization Group Explanations Conform to the Commonality Strategy? [Preprint]

The puzzle of half-integral quanta in the application of the adiabatic hypothesis to rotational motion

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

on 2016-2-19 3:45am GMT

Publication date: May 2016
Source:Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics, Volume 54
Author(s): Anthony Duncan, Enric Pérez
We present and discuss an interesting and puzzling problem Ehrenfest found in his first application of the adiabatic hypothesis, in 1913. It arose when trying to extend Planck׳s quantization of the energy of harmonic oscillators to a rotating dipole within the frame of the old quantum theory. Such an extension seemed to lead unavoidably to half-integral values for the rotational angular momentum of a system (in units of ℏ). We present the problem in its original form along with the (few) responses we have found to Ehrenfest׳s treatment. After giving a brief account of the classical and quantum adiabatic theorem, we also describe how Quantum Mechanics provides an explanation for this difficulty.

On the uncomputability of the spectral gap. (arXiv:1602.05924v1 [quant-ph])

quant-ph updates on arXiv.org

on 2016-2-19 1:31am GMT

Authors: Seth Lloyd

This paper reviews the 1994 proof that the spectral gap of Hamiltonian quantum systems capable of universal computation is uncomputable.

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Quantum statistical gravity: time dilation due to local information in many-body quantum systems. (arXiv:1602.05707v1 [quant-ph])

quant-ph updates on arXiv.org

on 2016-2-19 1:31am GMT

Authors: Dries SelsMichiel Wouters

We propose a generic mechanism for the emergence of a gravitational potential that acts on all classical objects in a quantum system. Our conjecture is based on the analysis of mutual information in many-body quantum systems. Since measurements in quantum systems affect the surroundings through entanglement, a measurement at one position reduces the entropy in its neighbourhood. This reduction in entropy can be described by a local temperature, that is directly related to the gravitational potential. A crucial ingredient in our argument is that ideal classical mechanical motion occurs at constant probability. This definition is motivated by the analysis of entropic forces in classical systems, which can be formally rewritten in terms of a gravitational potential.

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Constraints on the noise in dynamical reduction models

ScienceDirect Publication: Physics Letters A

on 2016-2-18 11:12am GMT

Publication date: 22 March 2016
Source:Physics Letters A, Volume 380, Issue 13
Author(s): Kyrylo Simonov, Beatrix C. Hiesmayr
The dynamics of a quantum system with internal degrees of freedom undergoing spontaneous collapse in the position basis are analysed; e.g., neutral mesons or neutrinos. Surprisingly, the value of the Heaviside function θ ( x ) at x = 0 that can in general be chosen in the interval [ 0 , 1 ] leads to different physical predictions. For the QMUPL (Quantum Mechanics with Universal Position Localization) model only a single value leads to probabilities conserving the particle number. Herewith the physical properties of the noise field can be constrained. This opens a road to study the physical properties of the noise field essential for collapse models.

Gravitational wave tests of quantum modifications to black hole structure. (arXiv:1602.03622v1 [gr-qc] CROSS LISTED)

hep-th updates on arXiv.org

on 2016-2-18 1:31am GMT

Authors: Steven B. Giddings

A preliminary discussion is given of the prospects that gravitational-wave observations of binary inspiral of black holes could reveal or constrain quantum modifications to black hole dynamics, such as are required to preserve postulates of quantum mechanics. Different proposals for such modifications are characterized by different scales, and the size of these scales relative to those probed by observation of inspiral signals is important in determining the feasibility of finding experimental signatures. Certain scenarios with strong quantum modifications in a region extending well outside the horizon are expected to modify classical evolution, and distort the near-peak gravitational wave signal, suggesting a search for anomalies such as decreased regularity of the signal and increased power.

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Hilbert Space Quantum Mechanics is Contextual (Reply to R. B. Griffiths). (arXiv:1502.05396v2 [quant-ph] UPDATED)

quant-ph updates on arXiv.org

on 2016-2-18 1:31am GMT

Authors: Christian de Ronde

In a recent paper Griffiths [38] has argued, based on the consistent histories interpretation, that Hilbert space quantum mechanics (QM) is noncontextual. According to Griffiths the problem of contextuality disappears if the apparatus is “designed and operated by a competent experimentalist” and we accept the Single Framework Rule (SFR). We will argue from a representational realist stance that the conclusion is incorrect due to the misleading understanding provided by Griffiths to the meaning of quantum contextuality and its relation to physical reality and measurements. We will discuss how the quite general incomprehension of contextuality has its origin in the “objective-subjective omelette” created by Heisenberg and Bohr. We will argue that in order to unscramble the omelette we need to disentangle, firstly, representational realism from naive realism, secondly, ontology from epistemology, and thirdly, the different interpretational problems of QM. In this respect, we will analyze what should be considered as Meaningful Physical Statements (MPS) within a theory and will argue that Counterfactual Reasoning (CR) -considered by Griffiths as “tricky”- must be accepted as a necessary condition for any representational realist interpretation of QM. Finally we discuss what should be considered as a problem (and what not) in QM from a representational realist perspective.

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A Review of Student Difficulties in Upper-Level Quantum Mechanics. (arXiv:1504.02056v2 [physics.ed-ph] CROSS LISTED)

quant-ph updates on arXiv.org

on 2016-2-18 1:31am GMT

Authors: Chandralekha SinghEmily Marshman

Learning advanced physics, in general, is challenging not only due to the increased mathematical sophistication but also because one must continue to build on all of the prior knowledge acquired at the introductory and intermediate levels. In addition, learning quantum mechanics can be especially challenging because the paradigms of classical mechanics and quantum mechanics are very different. Here, we review research on student reasoning difficulties in learning upper-level quantum mechanics and research on students’ problem-solving and metacognitive skills in these courses. Some of these studies were multi-university investigations. The investigations suggest that there is large diversity in student performance in upper-level quantum mechanics regardless of the university, textbook, or instructor and many students in these courses have not acquired a functional understanding of the fundamental concepts. The nature of reasoning difficulties in learning quantum mechanics is analogous to reasoning difficulties found via research in introductory physics courses. The reasoning difficulties were often due to over-generalizations of concepts learned in one context to another context where they are not directly applicable. Reasoning difficulties in distinguishing between closely related concepts and in making sense of the formalism of quantum mechanics were common. We conclude with a brief summary of the research-based approached that take advantage of research on student difficulties in order to improve teaching and learning of quantum mechanics.

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A Framework for Understanding the Patterns of Student Reasoning Difficulties in Quantum Mechanics. (arXiv:1504.02042v1 [physics.ed-ph] CROSS LISTED)

quant-ph updates on arXiv.org

on 2016-2-18 1:31am GMT

Authors: Emily MarshmanChandralekha Singh

Compared with introductory physics, relatively little is known about the development of expertise in advanced physics courses, especially in the case of quantum mechanics. Here, we describe a framework for understanding the patterns of student reasoning difficulties and how students develop expertise in quantum mechanics. The framework posits that the challenges many students face in developing expertise in quantum mechanics are analogous to the challenges introductory students face in developing expertise in introductory classical mechanics. This framework incorporates both the diversity in upper-level students’ prior preparation, goals, and motivation in general (i.e., the facts that even in upper-level courses, students may be inadequately prepared, have unclear goals, and have insufficient motivation to excel) as well as the “paradigm shift” from classical mechanics to quantum mechanics. The framework is based on empirical investigations demonstrating that the patterns of reasoning, problem-solving, and self-monitoring difficulties in quantum mechanics bear a striking resemblance to those found in introductory classical mechanics. Examples from research in quantum mechanics and introductory classical mechanics are discussed to illustrate how the patterns of difficulties are analogous as students learn to unpack the respective principles and grasp the formalism in each knowledge domain during the development of expertise. Embracing such a framework and contemplating the parallels between the difficulties in these two knowledge domains can enable researchers to leverage the extensive literature for introductory physics education research to guide the design of teaching and learning tools for helping students develop expertise in quantum mechanics.

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On Quantum Theory. (arXiv:1602.05426v1 [quant-ph])

quant-ph updates on arXiv.org

on 2016-2-18 1:31am GMT

Authors: Rudolf Haag

A discussion of fundamental aspects of quantum theory is presented, stressing the essential role of “events”. (Abstract by Erhard Seiler — see afterword)

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Representational Realism, Closed Theories and the Quantum to Classical Limit. (arXiv:1602.05405v1 [quant-ph])

quant-ph updates on arXiv.org

on 2016-2-18 1:31am GMT

Authors: Christian de Ronde

In this paper we discuss the representational realist stance as a pluralist ontic approach to inter-theoretic relationships. Our stance stresses the fact that physical theories require the necessary consideration of a conceptual level of discourse which determines and configures the specific field of phenomena discussed by each particular theory. We will criticize the orthodox line of research which has grounded the analysis about QM in two (Bohrian) metaphysical presuppositions -accepted in the present as dogmas that all interpretations must follow. We will also examine how the orthodox project of “bridging the gap” between the quantum and the classical domains has constrained the possibilities of research, producing only a limited set of interpretational problems which only focus in the justification of “classical reality” and exclude the possibility of analyzing the possibilities of non-classical conceptual representations of QM. The representational realist stance introduces two new problems, namely, the superposition problem and the contextuality problem, which consider explicitly the conceptual representation of orthodox QM beyond the mere reference to mathematical structures and measurement outcomes. In the final part of the paper, we revisit, from a representational realist perspective, the quantum to classical limit and the orthodox claim that this inter-theoretic relation can be explained through the principle of decoherence.

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Quantum Reduced Loop Gravity and the foundation of Loop Quantum Cosmology. (arXiv:1602.05475v1 [gr-qc])

gr-qc updates on arXiv.org

on 2016-2-18 1:30am GMT

Authors: Emanuele AlesciFrancesco Cianfrani

Quantum Reduced Loop Gravity is a promising framework for linking Loop Quantum Gravity and the effective semiclassical dynamics of Loop Quantum Cosmology. We review its basic achievements and its main perspectives, outlining how it provides a quantum description of the Universe in terms of a cuboidal graph which constitutes the proper framework for applying loop techniques in a cosmological setting.

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Extreme Violation of Local Realism in Quantum Hypergraph States

PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

on 2016-2-17 3:00pm GMT

Author(s): Mariami Gachechiladze, Costantino Budroni, and Otfried Gühne

Hypergraph states form a family of multiparticle quantum states that generalizes the well-known concept of Greenberger-Horne-Zeilinger states, cluster states, and more broadly graph states. We study the nonlocal properties of quantum hypergraph states. We demonstrate that the correlations in hypergr…

 

[Phys. Rev. Lett. 116, 070401] Published Wed Feb 17, 2016

Category theory and physical structuralism

Latest Results for European Journal for Philosophy of Science

on 2016-2-17 12:00am GMT

Abstract

As a metaphysical theory, radical ontic structural realism (ROSR) is characterised mainly in terms of the ontological primacy it places on relations and structures, as opposed to the individual relata and objects that inhabit these relations/structures. The most popular criticism of ROSR is that its central thesis (that there can exist ‘relations without relata’) is incoherent. Bain (Synthese, 190, 1621–1635, 2013) attempts to address this criticism by arguing that the mathematical language of category theory allows for a coherent articulation of ROSR’s key thesis. Subsequently, Wüthrich and Lam (2014) and Lal and Teh (2015) have criticised Bain’s arguments and claimed that category theory fares no better than set theory in coherently articulating the main ideas of ROSR. In this paper, we defend Bain’s main arguments against these critiques, and attempt to elaborate on the sense in which category theory can be seen as providing a coherent articulation of ROSR. We also consider the relationship between ROSR and Categorical Quantum Mechanics.

Young scientists poised to ride the gravitational wave

Nature News & Comment

on 2016-2-16 12:00am GMT

Detection of ripples in space-time kicks off new era in physics.

Nature 530 263 doi: 10.1038/530263a

 

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