# Weekly Papers on Quantum Foundations (40)

Gravity-related collapse of the wave function and spontaneous heating: revisiting the experimental bounds. (arXiv:2109.14980v1 [quant-ph])

The possibility that the collapse of the wave function in quantum mechanics is a real and ultimately connected to (classical) gravity has been debated for decades, with main contributions by Di\’osi and Penrose. In particular, Di\’osi proposed a noise-based dynamical reduction model, which captures the same orders of magnitude for the collapse time suggested by Penrose based on heuristic arguments. This is known in literature as the DP model (Di\’osi-Penrose). A peculiarity of the DP model is the prediction of spontaneous heating of matter, which can be tested without the need for massive quantum superpositions. Notably, a very similar effect is predicted by recent theoretical approaches to gravity as a classical-only information channel. Here, we reconsider the current constraints on the DP model from spontaneous heating, by analyzing experimental situations not properly considered before. We argue that the the parameter-free version of the DP model is close to be ruled out by standard heat leak measurements at ultralow temperature, with a conclusive exclusion likely within reach with existing technology. This result would strengthen a recent claim of exclusion inferred by spontaneous x-ray emission experiments, which relies on the somewhat stronger assumption that the DP noise field is white up to x-ray frequencies.

A critical discussion of different methods and models in Casimir effect. (arXiv:2109.15155v1 [quant-ph])

The Casimir-Lifshitz force acts between neutral material bodies and is due to the fluctuations (around zero) of the electrical polarizations of the bodies. This force is a macroscopic manifestation of the van der Waals forces between atoms and molecules. There are two different approaches in the theory of this force. One is centered on the fluctuations inside the bodies, as the source of the fluctuational electromagnetic fields and forces. The second approach is based on finding the eigenmodes of the field, while the material bodies are assumed to be passive and non-fluctuating. Although both approaches have a long history, there are still some misconceptions in the literature. In particular, there are claims that (hypothetical) materials with a strictly real dielectric function $\varepsilon(\omega)$ can give rise to fluctuational Casimir-Lifshitz forces. We review and compare the two approaches, using the simple example of the force in the absence of retardation. We point out that also in the second (the “field-oriented”) approach one cannot avoid introducing an infinitesimal imaginary part into the dielectric function, i.e. introducing some dissipation. Furthermore, we emphasize that the requirement of analyticity of $\varepsilon(\omega)$ in the upper half of the complex $\omega$ plane is not the only one for a viable dielectric function. In particular, models that use a strictly real $\varepsilon(\omega)$ (for all real positive $\omega)$ are inadmissible and lead to various contradictions and inconsistencies. Specifically, we present a critical discussion of the “dissipation-less plasma model”. Our emphasis is not on the most recent developments in the field but on some conceptual, not fully resolved issues.

Generalized Uncertainty Principle: from the harmonic oscillator to a QFT toy model. (arXiv:2109.15259v1 [hep-th])

Several models of quantum gravity predict the emergence of a minimal length at Planck scale. This is commonly taken into consideration by modifying the Heisenberg Uncertainty Principle into the Generalized Uncertainty Principle. In this work, we study the implications of a polynomial Generalized Uncertainty Principle on the harmonic oscillator. We revisit both the analytic and algebraic methods, deriving the exact form of the generalized Heisenberg algebra in terms of the new position and momentum operators. We show that the energy spectrum and eigenfunctions are affected in a non-trivial way. Furthermore, a new set of ladder operators is derived which factorize the Hamiltonian exactly. The above formalism is finally exploited to construct a quantum field theoretic toy model based on the Generalized Uncertainty Principle.

Is the Universe actually holographic?. (arXiv:2109.15022v1 [hep-th])

In this letter, we are going to reexamine the holographic dark energy concept that is proposed for cosmological applications. By considering precisely the bounds on the entropy arisen from lattice field theory on one side and Bekenstein-Hawking entropy of black holes on another side, it is shown that the so-called holographic dark energy can not be mimicked as easily as claimed in the literature. In addition, the limits which are discussed in the literature on the electron $(g-2)$ experiments, are rediscussed here. It is shown that the corrections to the electron magnetic momentum should be of the order of ${O}(10^{-23})$

An Argument for Strong Positivity of the Decoherence Functional. (arXiv:2011.06120v2 [quant-ph] UPDATED)

Authors: Fay DowkerHenry Wilkes

We give an argument for strong positivity of the decoherence functional as the correct, physical positivity condition in formulations of quantum theory based fundamentally on the path integral. We extend to infinite systems work by Boes and Navascues that shows that the set of strongly positive quantum systems is maximal amongst sets of systems that are closed under tensor product composition. We show further that the set of strongly positive quantum systems is the unique set that is maximal amongst sets that are closed under tensor product composition.

On the relationship between geometric objects and figures in Euclidean geometry

Bacelar Valente, Mario (2021) On the relationship between geometric objects and figures in Euclidean geometry. [Preprint]

Momentum Entanglement for Atom Interferometry

Author(s): F. Anders, A. Idel, P. Feldmann, D. Bondarenko, S. Loriani, K. Lange, J. Peise, M. Gersemann, B. Meyer-Hoppe, S. Abend, N. Gaaloul, C. Schubert, D. Schlippert, L. Santos, E. Rasel, and C. Klempt

Compared to light interferometers, the flux in cold-atom interferometers is low and the associated shot noise is large. Sensitivities beyond these limitations require the preparation of entangled atoms in different momentum modes. Here, we demonstrate a source of entangled atoms that is compatible w…

[Phys. Rev. Lett. 127, 140402] Published Wed Sep 29, 2021

There Is No Measurement Problem for Humeans

Dorst, Chris (2021) There Is No Measurement Problem for Humeans. [Preprint]

On Two Different Kinds of Computational Indeterminacy

Papayannopoulos, Philippos and Fresco, Nir and Shagrir, Oron (2021) On Two Different Kinds of Computational Indeterminacy. [Preprint]

MOND and Methodology

Merritt, David (2021) MOND and Methodology. Karl Popper’s Science and Philosophy. pp. 69-96.

Einstein’s Wonder

Gasco, Enrico (2020) Einstein’s Wonder. Proceedings of the XL SISFA Conference, 2021. pp. 125-131.

Why Bell’s Everett (?) theory is wrong

Gao, Shan (2021) Why Bell’s Everett (?) theory is wrong. [Preprint]

Representation and the Quantum State

Healey, Richard A. (2021) Representation and the Quantum State. [Preprint]

Laws as Epistemic Infrastructure not Metaphysical Superstructure

Healey, Richard A. (2021) Laws as Epistemic Infrastructure not Metaphysical Superstructure. [Preprint]

States of Ignorance and Ignorance of States: Examining the Quantum Principal Principle

Meehan, Alexander (2021) States of Ignorance and Ignorance of States: Examining the Quantum Principal Principle. [Preprint]

The Closure of the Physical is Unscientific

Kleiner, Johannes and Stephan, Hartmann (2021) The Closure of the Physical is Unscientific. [Preprint]

Review of Causation in Science by Yemima Ben-Menahem

Farr, Matt (2021) Review of Causation in Science by Yemima Ben-Menahem. [Preprint]