Weekly Papers on Quantum Foundations (14)

The classical-quantum hybrid canonical dynamics and its difficulties with special and general relativity 

from gr-qc by Lajos Di\’osiFri Apr 12 2024 14:58:09 (18 hours)# 1.

arXiv:2404.07723v1 Announce Type: new Abstract: We discuss the Hamiltonian hybrid coupling between a classical and a quantum subsystem. If applicable to classical gravity coupled to quantized matter, this hybrid theory might realize a captivating `postquantum’ alternative to full quantum-gravity. We summarize the nonrelativistic hybrid dynamics in improved formalism adequate to Hamiltonian systems. The mandatory decoherence and diffusion terms become divergent in special and general relativistic extensions. It is not yet known if any renormalization method might reconcile Markovian decoherence and diffusion with relativity. Postquantum gravity could previously only be realized in the Newtonian approximation. We argue that pending problems of the recently proposed general relativistic postquantum theory will not be solved if Markovian diffusion/decoherence are truly incompatible with relativity.

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Maximum and minimum causal effects of quantum processes 

from quant-ph by Kaumudibikash Goswami, Giulio ChiribellaFri Apr 12 2024 14:58:00 (18 hours)# 2.

arXiv:2404.07683v1 Announce Type: new Abstract: We introduce two quantitative measures of the strength of causal relations. These two measures capture the maximum and minimum changes in a quantum system induced by changes in another system. We show that both measures possess important properties, such as continuity and faithfulness, and can be evaluated through optimization over orthogonal input states. For the maximum causal effect, we provide numerical lower bounds based on a variational algorithm, which can be used to estimate the strength of causal relations without performing a full quantum process tomography. To illustrate the application of our algorithm, we analyze two paradigmatic examples, the first involving a coherent superposition of direct cause and common cause and the second involving communication through a coherent superposition of two completely depolarizing channels.

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U(2) Is Right for Leptons and Left for Quarks 

from PRL by Stefan Antusch, Admir Greljo, Ben A. Stefanek, and Anders Eller ThomsenFri Apr 12 2024 06:00:00 (1 day)# 3.

Author(s): Stefan Antusch, Admir Greljo, Ben A. Stefanek, and Anders Eller Thomsen

We posit that the distinct patterns observed in fermion masses and mixings are due to a minimally broken U(2)�+� flavor symmetry acting on left-handed quarks and right-handed charged leptons, giving rise to an accidental U(2)5 symmetry at the renormalizable level without imposing selection rules on …

[Phys. Rev. Lett. 132, 151802] Published Fri Apr 12, 2024

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Three Puzzles with Covariance and Supertranslation Invariance of Angular Momentum Flux and Their Solutions 

from PRL by Reza Javadinezhad and Massimo PorratiFri Apr 12 2024 06:00:00 (1 day)# 4.

Author(s): Reza Javadinezhad and Massimo Porrati

We describe and solve three puzzles arising in covariant and supertranslation-invariant formulas for the flux of angular momentum and other Lorentz charges in asymptotically flat spacetimes: (i) Supertranslation invariance and covariance imply invariance under spacetime translations; (ii) the flux d…

[Phys. Rev. Lett. 132, 151604] Published Fri Apr 12, 2024

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Creative and geometric times in physics, mathematics, logic, and philosophy 

from physics.hist-ph by Flavio Del Santo, Nicolas GisinThu Apr 11 2024 11:52:20 (1 day)# 5.

arXiv:2404.06566v1 Announce Type: new Abstract: We propose a distinction between two different concepts of time that play a role in physics: geometric time and creative time. The former is the time of deterministic physics and merely parametrizes a given evolution. The latter is instead characterized by real change, i.e. novel information that gets created when a non-necessary event becomes determined in a fundamentally indeterministic physics. This allows us to give a naturalistic characterization of the present as the moment that separates the potential future from the determined past. We discuss how these two concepts find natural applications in classical and intuitionistic mathematics, respectively, and in classical and multivalued tensed logic, as well as how they relate to the well-known A- and B-theories in the philosophy of time.

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Causal links between operationally independent events in quantum theory 

from PRA – fundamentalconcepts by Shubhayan SarkarThu Apr 11 2024 06:00:00 (2 days)# 6.

Author(s): Shubhayan Sarkar

The work challenges the concept of “classical independence” between physical systems by demonstrating that within quantum theory two systems can affect each other despite no observable changes, unveiling the interconnected nature of the quantum world. The findings also unveil potential applications for device-independent certification of quantum states and measurements.

[Phys. Rev. A 109, L040202] Published Thu Apr 11, 2024

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Did Louis de Broglie miss the discovery of the Schr\”odinger equation? 

from physics.hist-ph by Aur\’elien DrezetWed Apr 10 2024 10:24:31 (2 days)# 7.

arXiv:2404.06366v1 Announce Type: new Abstract: In this note, we discuss a historical point regarding Schr\”odinger’s discovery of the famous quantum wave equation in 1926 following de Broglie’s fundamental works published in 1923-1925 regarding the introduction of matter waves. Drawing on the work of historians and personal analysis, we show that de Broglie was very close to the discovery of the Schr\”odinger equation (at least for the stationary one-electron problem).

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Reconstructions of Quantum Theory: Methodology and the Role of Axiomatization 

from philsciTue Apr 09 2024 18:34:23 (3 days)# 8.

Oddan, Jessica (2024) Reconstructions of Quantum Theory: Methodology and the Role of Axiomatization. [Preprint]

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