Weekly Papers on Quantum Foundations (6)

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

Relations Between Different Notions of Degrees of Freedom of a Quantum System and Its Classical Model

Latest Results for Foundations of Physics

on 2015-2-06 12:00am GMT

Abstract

There are at least three different notions of degrees of freedom (DF) that are important in comparison of quantum and classical dynamical systems. One is related to the type of dynamical equations and inequivalent initial conditions, the other to the structure of the system and the third to the properties of dynamical orbits. In this paper, definitions and comparison in classical and quantum systems of the tree types of DF are formulated and discussed. In particular, we concentrate on comparison of the number of the so called dynamical DF in a quantum system and its classical model. The comparison involves analyzes of relations between integrability of the classical model, dynamical symmetry and separability of the quantum and the corresponding classical systems and dynamical generation of appropriately defined quantumness. The analyzes is conducted using illustrative typical systems. A conjecture summarizing the observed relation between generation of quantumness by the quantum dynamics and dynamical properties of the classical model is formulated.

Schrodinger Evolution for the Universe: Reparametrization. (arXiv:1502.01225v1 [gr-qc])

gr-qc updates on arXiv.org

on 2015-2-05 3:07am GMT

Authors: Sean GrybKarim Thebault

Starting from a generalized Hamilton-Jacobi formalism, we develop a new framework for constructing observables and their evolution in theories invariant under global time reparametrizations. Our proposal relaxes the usual Dirac prescription for the observables of a totally constrained system (`perennials’) and allows one to recover the influential partial and complete observables approach in a particular limit. Difficulties such as the non-unitary evolution of the complete observables in terms of certain partial observables are explained as a breakdown of this limit. Identification of our observables (`mutables’) relies upon a physical distinction between gauge symmetries that exist at the level of histories and states (`Type 1′), and those that exist at the level of histories and not states (`Type 2′). This distinction resolves a tension in the literature concerning the physical interpretation of the partial observables and allows for a richer class of observables in the quantum theory. There is the potential for the application of our proposal to the quantization of gravity when understood in terms of the Shape Dynamics formalism.

Testing Spontaneous Wave-Function Collapse Models on Classical Mechanical Oscillators

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

on 2015-2-04 3:00pm GMT

Author(s): Lajos Diósi

We show that the heating effect of spontaneous wave-function collapse models implies an experimentally significant increment ΔTsp of equilibrium temperature in a mechanical oscillator. The obtained new form ΔTsp is linear in the oscillator’s relaxation time τ and independent of the mass. The oscilla…

[Phys. Rev. Lett. 114, 050403] Published Wed Feb 04, 2015

Comment on QBism and locality in quantum mechanics. (arXiv:1502.00123v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-2-03 1:55am GMT

Authors: Michael Nauenberg

A critique to the article by C.A. Fuchs, N.D. Mermin, and R.Schack, “An introduction to QBism with and application to the locality of quantum mechanics” that appeared in Am. J. Phys. 82 (8), 749-754 (2014)

The other QFT

Nature Physics – Issue – nature.com science feeds

on 2015-2-03 12:00am GMT

Nature Physics 11, 108 (2015). doi:10.1038/nphys3167

Authors: Peter Hänggi & Peter Talkner

Fluctuation theorems go beyond the linear response regime to describe systems far from equilibrium. But what happens to these theorems when we enter the quantum realm? The answers, it seems, are now coming thick and fast.

Measurements on the reality of the wavefunction

Nature Physics – AOP – nature.com science feeds

on 2015-2-02 12:00am GMT

Nature Physics. doi:10.1038/nphys3233

Authors: M. Ringbauer, B. Duffus, C. Branciard, E. G. Cavalcanti, A. G. White & A. Fedrizzi

Answer to Giancarlo Ghirardi: Quantum Superpositions and Definite Perceptions: Envisaging New Feasible Experimental Tests. A Novel Proposal for Quantum Mechanics, Perception and Cognitive Science?

Latest Results for International Journal of Theoretical Physics

on 2015-2-01 12:00am GMT

Abstract

We give answer to a previous experiment that time ago was proposed by G. Ghirardi evidencing that in such last years detailed experiments have been performed on this matter giving convincing results and that still more experiments, rather simple and not expensive, may be realized.

A formal framework for the study of the notion of undefined particle number in quantum mechanics

Latest Results for Synthese

on 2015-2-01 12:00am GMT

Abstract

It is usually stated that quantum mechanics presents problems with the identity of particles, the most radical position—supported by E. Schrödinger—asserting that elementary particles are not individuals. But the subject goes deeper, and it is even possible to obtain states with an undefined particle number. In this work we present a set theoretical framework for the description of undefined particle number states in quantum mechanics which provides a precise logical meaning for this notion. This construction goes in the line of solving a problem posed by Y. Manin, namely, to incorporate quantum mechanical notions at the foundations of mathematics. We also show that our system is capable of representing quantum superpositions.

 

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