arXiv subjects

Gabriel H. S. Aguiar

Publications and source records attributed to Gabriel H. S. Aguiar.

5 recordsLinked to original sources

arXiv2026

Will we ever quantize the centers of mass of heavy systems? A case for a Heisenberg cut in quantum mechanics

The quantum orthodoxy attests that all dynamical degrees of freedom should be quantized, including those associated with the centers of mass of composite/complex systems, such as protons/pebbles. By assuming that the centers of mass of protons/pebbles should be quantized, one implies the existence of a corresponding Fock space, since, according to the present lore, quantum mechanics is a consequence of quantum field theory. Despite the fabulous success of quantum mechanics, it is unreasonable to assume the existence of annihilation and creation operators for pebbles. Fortunately, there are strong reasons to doubt that wave mechanics can describe the centers of mass of systems at or above the Planck scale, thereby jeopardizing the construction of the corresponding Fock space. We argue that isolated (free) systems with masses exceeding the Planck mass would have their centers of mass governed by classical (rather than quantum) mechanics, despite harboring macroscopic quantum phenomena as observed in the laboratory. Here, we briefly revisit (i) the arguments for the need for a Heisenberg cut delimiting the boundary between the quantum and classical realms and (ii) the kind of new physics expected at (the uncharted region of) the Heisenberg cut.

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arXiv2025

Quantum internal vibrations in macroscopic systems with classical centers of mass

Harmonizing classical and quantum worlds is a major challenge for modern physics. A significant portion of the scientific community supports the notion that classical mechanics is an effective theory that arises from quantum mechanics. Recently, the present authors have argued that this should not be the case, as quantum mechanics is not trustworthy for describing the center of mass of systems with masses $m$ much larger than the Planck mass $M_\text{P}$. In this vein, a simple gravitational self-decoherence model was proposed, describing how the center of mass of quantum systems would classicalize for $m \sim M_\text{P}$. Here, we show that our model does not prevent macroscopic systems (with classical centers of mass) from harboring quantum internal vibrations (as has been observed in the laboratory).

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arXiv2025

A simple gravitational self-decoherence model

One of the most significant debates of our time is whether our macroscopic world (i) naturally emerges from quantum mechanics or (ii) requires new physics. We argue for the latter and propose a simple gravitational self-decoherence mechanism. For this purpose, we postulate the existence of a Heisenberg cut such that particles with masses $m$ much smaller and larger than a critical mass $M_{\rm C}$ (of the order of the Planck mass $M_{\rm P}$) would be necessarily treated according to quantum and classical rules, respectively. Our effective model is designed to capture the new physics that free quantum particles would experience as their masses approach $M_{\rm C}$. The purity loss for free quantum particles is evaluated and shown to be highly inefficient for quantum particles with $m \ll M_{\rm C}$ but very effective for those with $m \sim M_{\rm C}$. The physical picture behind it is that coherence would (easily) leak from heavy enough particles to (non-observable) spacetime quantum degrees of freedom. Finally, we contextualize our proposal with state-of-the-art experiments and show how it can be tested in a future Stern-Gerlach-like experiment.

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arXiv2024

Probing the Schroedinger-Newton equation in a Stern-Gerlach interferometer

Explaining the behavior of macroscopic objects from the point of view of the quantum paradigm has challenged the scientific community for a century today. A mechanism of gravitational self-interaction, governed by the so-called Schroedinger-Newton equation, is among the proposals that aim to shed some light on it. Despite all efforts, this mechanism has been proven difficult to probe. Here, we consider a simple Stern-Gerlach-like experiment to try it out. The Schroedinger-Newton equation can be analytically solved under certain proper conditions, and a dephasing effect induced by the gravitational self-interacting potential can be calculated.

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arXiv2023

Disfavoring the Schroedinger-Newton equation

The main goal of this brief report is to provide some new insight into how promising the Schroedinger-Newton equation would be to explain the emergence of classicality. Based on the similarity of the Newton and Coulomb potentials, we add an electric self-interacting term to the Schroedinger-Newton equation for the hydrogen atom. Our results rule out the possibility that single electrons self-interact through their electromagnetic field. Next, we use the hydrogen atom to get insight into the intrinsic difficulty of testing the Schroedinger-Newton equation itself and conclude that the Planck scale must be approached before sound constraints are established. Although our results cannot be used to rule out the Schroedinger-Newton equation at all, they might be seen as disfavoring it if we underpin on the resemblance between the gravitational and electromagnetic interactions at low energies.

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