Weekly Papers on Quantum Foundations (9)

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.

An instability of unitary quantum dynamics. (arXiv:1502.07527v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-3-01 1:12am GMT

Authors: Jasper van Wezel

Instabilities of equilibrium quantum mechanics are common and well-understood. They are manifested for example in phase transitions, where a quantum system becomes so sensitive to perturbations that a symmetry can be spontaneously broken. Here, we consider the possibility that the time evolution governing quantum dynamics may be similarly subject to an instability, at which its unitarity spontaneously breaks down owing to an extreme sensitivity towards perturbations. We find that indeed such an instability exists, and we explore its immediate consequences. Interpretations of the results both in terms of extreme sensitivity to the influence of environmental degrees of freedom, and in terms of a possible fundamental violation of unitarity are discussed.

Gauging Quantum States: From Global to Local Symmetries in Many-Body Systems

Recent Articles in Phys. Rev. X

on 2015-2-27 3:00pm GMT

Author(s): Jutho Haegeman, Karel Van Acoleyen, Norbert Schuch, J. Ignacio Cirac, and Frank Verstraete

Gauge fields, which appear in the standard model of physics, underpin a variety of fields, including condensed-matter physics. An alternative technique for studying gauge theories using a lattice with quantum degrees of freedom at its vertices is presented.

[Phys. Rev. X 5, 011024] Published Fri Feb 27, 2015

The Schrödinger–Newton system with self-field coupling

Classical and Quantum Gravity – latest papers

on 2015-2-27 12:00am GMT

We study the Schrödinger–Newton (SN) system of equations with the addition of gravitational field energy sourcing—such additional nonlinearity is to be expected from a theory of gravity (like general relativity (GR)), and its appearance in this simplified scalar setting (one of Einstein’s precursors to GR) leads to significant changes in the spectrum of the self-gravitating theory. Using an iterative technique, we compare the mass dependence of the ground state energies of both SN and the new, self-sourced system and find that they are dramatically different. The Bohr method approach from old quantization provides a qualitative description of the difference, which comes from the additional nonlinearity introduced in the self-sourced case. In addition to comparison of ground state energies, we calculate the transition energy between the ground state and first excited state to compare emission frequencies between SN and the self-coupled scalar case.

Time symmetry in wave function collapse models. (arXiv:1502.07092v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-2-26 10:30am GMT

Authors: Daniel Bedingham

A framework for wave function collapse models that is symmetric under time reversal is presented. Within this framework there are equivalent pictures of collapsing wave functions evolving in both time directions. The backwards-in-time Born rule can be broken by an initial condition on the Universe resulting in asymmetric behaviour. Similarly the forwards-in-time Born rule can in principle be broken by a final condition on the Universe.

The Black Hole Information Paradox and the Collapse of the Wave Function

Latest Results for Foundations of Physics

on 2015-2-26 12:00am GMT


The black hole information paradox arises from an apparent conflict between the Hawking black hole radiation and the fact that time evolution in quantum mechanics is unitary. The trouble is that while the former suggests that information of a system falling into a black hole disappears, the latter implies that information must be conserved. In this work we discuss the current divergence in views regarding the paradox, we evaluate the role that objective collapse theories could play in its resolution and we propose a link between spontaneous collapse events and microscopic virtual black holes.

Quantum Logic and Quantum Reconstruction

Latest Results for Foundations of Physics

on 2015-2-26 12:00am GMT


Quantum logic understood as a reconstruction program had real successes and genuine limitations. This paper offers a synopsis of both and suggests a way of seeing quantum logic in a larger, still thriving context.

Pure wave mechanics and the very idea of empirical adequacy

Latest Results for Synthese

on 2015-2-26 12:00am GMT


Hugh Everett III proposed his relative-state formulation of pure wave mechanics as a solution to the quantum measurement problem. He sought to address the theory’s determinate record and probability problems by showing that, while counterintuitive, pure wave mechanics was nevertheless empirically faithful and hence empirical acceptable. We will consider what Everett meant by empirical faithfulness. The suggestion will be that empirical faithfulness is well understood as a weak variety of empirical adequacy. The thought is that the very idea of empirical adequacy might be renegotiated in the context of a new physical theory given the theory’s other virtues. Everett’s argument for pure wave mechanics provides a concrete example of such a renegotiation.

Colloquium: Time-reversal violation with quantum-entangled B mesons

Recent Articles in Rev. Mod. Phys.

on 2015-2-23 3:00pm GMT

Author(s): J. Bernabéu and F. Martínez-Vidal

One of the most important symmetries in nature is time reversal, namely, that the laws of physics remain dynamically invariant from moving forward to backward in time. Nevertheless, this symmetry can be broken in certain physical processes as observed in neutral B mesons by the BABAR Collaboration. …

[Rev. Mod. Phys. 87, 165] Published Mon Feb 23, 2015


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