# Weekly Papers on Quantum Foundations (36-37)

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Simon Portegies Zwart, Tjarda Boekholt

Sat Sep 10 2022 09:48:11 (1 hour)

# 1.

The fundamental laws of physics are time-symmetric, but our macroscopic experience contradicts this. The time reversibility paradox is partly a consequence of the unpredictability of Newton’s equations of motion. We measure the dependence of the fraction of irreversible, gravitational N-body systems on numerical precision and find that it scales as a power law. The stochastic wave packet reduction postulate then introduces fundamental uncertainties in the Cartesian phase space coordinates that propagate through classical three-body dynamics to macroscopic scales within the triple’s lifetime. The spontaneous collapse of the wave function then drives the global chaotic behavior of the Universe through the superposition of triple systems (and probably multi-body systems). The paradox of infinitesimal granularity then arises from the superposition principle, which states that any multi-body system is composed of an ensemble of three-body problems.

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Robert J. Scherrer

Sat Sep 10 2022 09:48:06 (1 hour)

# 2.

When the expansion of the universe is dominated by a perfect fluid with equation of state parameter $w$ and a sound speed $c_s$ satisfying $w = c_s^2 \le 1$, the Hubble parameter $H$ and time $t$ satisfy the bound $Ht \ge 1/3$. There has been recent interest in “ultra-slow” expansion laws with $Ht < 1/3$ (sometimes described as “fast expanding” models). We examine various models that can produce ultra-slow expansion: scalar fields with negative potentials, barotropic fluids, braneworld models, or a loitering phase in the early universe. Scalar field models and barotropic models for ultra-slow expansion are unstable to evolution toward $w = 1$ or $w \rightarrow \infty$ in the former case and $w \rightarrow \infty$ in the latter case. Braneworld models can yield ultra-slow expansion but require an expansion law beyond the standard Friedman equation. Loitering early universe models can produce a quasi-static expansion phase in the early universe but require an exotic negative-density component. These results suggest that appeals to an ultra-slow expansion phase in the early universe should be approached with some caution, although the loitering early universe may be worthy of further investigation. These results do not apply to ultra-slow contracting models.

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Chong-Sun Chu, Rong-Xin Miao

Sat Sep 10 2022 09:48:03 (1 hour)

# 3.

We propose that the quantum states of black hole responsible for the Bekenstein-Hawking entropy are given by a thin shell of Bell particles located at the region just underneath the horizon. We argue that the configuration can be stabilized by a new kind of degeneracy pressure which is suggested by noncommutative geometry. We utilize the work of Parikh and Wilczek to include the effect of tunneling on the Bell particles. We show that partially tunneled Bell particles give the Page curve for the Hawking radiation, and the entirety of information initially stored in the black hole is returned to the outside via the Hawking radiation. In view of entropic force, the location of these Bell states is naturally related to the island and the quantum extremal surface. Also, the thin shell of Bell particles may be interpreted as a firewall.

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Mani L. Bhaumik

Sat Sep 10 2022 09:44:32 (1 hour)

# 4.

Credible reasons are presented to reveal that many of the lingering century old enigmas, surrounding the behavior of at least an individual quantum particle, can be comprehended in terms of an objectively real specific wave function. This wave function is gleaned from the single particle energy-momentum eigenstate offered by the theory of space filling universal quantum fields that is an inevitable outcome of Dirac’s pioneering masterpiece. Examples of these well-known enigmas are wave particle duality, the de Broglie hypothesis, the uncertainty principle, wave function collapse, and predictions of measurement outcomes in terms of probability instead of certainty. Paul Dirac successfully incorporated special theory of relativity into quantum mechanics for the first time. This was accomplished through his ingenious use of matrices that allowed the equations of motion to maintain the necessary first order time derivative feature necessary for positive probability density. The ensuing Dirac equation for the electron led to the recognition of the mystifying quantized spin and magnetic moment as intrinsic properties in contrast to earlier ad hoc assumptions. The solution of his relativistic equation for the hydrogen atom produced results in perfect agreement with experimental data available at the time. The most far reaching prediction of the celebrated Dirac equation was the totally unexpected existence of anti-particles, culminating in the eventual development of the quantum field theory of the Standard Model that reveals the deepest secrets of the universe known to date.

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Olivia Y. Long, Kai Wang, Avik Dutt, Shanhui Fan

Sat Sep 10 2022 09:41:31 (1 hour)

# 5.

The duality of space and time in Maxwell’s equations has prompted interest in time boundaries and the accompanying temporal analog of spatial reflection and refraction. However, achieving observable time boundary effects at optical frequencies in real materials is challenging. In this work, we demonstrate that time reflection and refraction can be observed in a two-band model centered around a non-zero reference energy. Our model can be physically implemented in the synthetic frequency dimension as a system of two coupled dynamically-modulated ring resonators. We find that modulation at microwave frequencies is sufficient to observe time boundary effects for optical waves in synthetic frequency dimension. Our work shows that implementing multi-band models in synthetic dimensions opens a new avenue for further exploration of time boundaries.

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Sat Sep 10 2022 08:00:30 (3 hours)

# 6.

Castellani, Elena and Margoni, Emilia (2022) Renormalization Group Methods: Which Kind of Explanation? Studies in History and Philosophy of Science, 95. pp. 158-166.

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

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J. Stevens, D. Szombati, M. Maffei, C. Elouard, R. Assouly, N. Cottet, R. Dassonneville, Q. Ficheux, S. Zeppetzauer, A. Bienfait, A. N. Jordan, A. Auffèves, and B. Huard

Fri Sep 09 2022 18:00:00 (17 hours)

# 7.

Author(s): J. Stevens, D. Szombati, M. Maffei, C. Elouard, R. Assouly, N. Cottet, R. Dassonneville, Q. Ficheux, S. Zeppetzauer, A. Bienfait, A. N. Jordan, A. Auffèves, and B. Huard

Qubits are physical, a quantum gate thus not only acts on the information carried by the qubit but also on its energy. What is then the corresponding flow of energy between the qubit and the controller that implements the gate? Here we exploit a superconducting platform to answer this question in th…

[Phys. Rev. Lett. 129, 110601] Published Fri Sep 09, 2022

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Nature Physics

Thu Sep 08 2022 08:00:00 (2 days)

# 8.

Nature Physics, Published online: 08 September 2022; doi:10.1038/s41567-022-01766-x

It is easy to dismiss research into the foundations of quantum mechanics as irrelevant to physicists in other areas. Adopting this attitude misses opportunities to appreciate the richness of quantum mechanics.

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Nature Physics

by

Karin Cedergren

Thu Sep 08 2022 08:00:00 (2 days)

# 9.

Nature Physics, Published online: 08 September 2022; doi:10.1038/s41567-022-01746-1

Although the ohm is ‘only’ a derived SI unit, the assumption that it plays an unobtrusive role could not be further from the truth, as Karin Cedergren reveals.

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Thu Sep 08 2022 05:08:47 (2 days)

# 10.

Franklin, Alexander and Robertson, Katie (2022) A Middle Way: A Non-Fundamental Approach to Many-Body Physics by Robert Batterman: Autonomy and Varieties of Reduction. [Preprint]

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Wed Sep 07 2022 02:10:48 (3 days)

# 11.

Ellerman, David (2022) Follow the Math!:The mathematics of quantum mechanics as the mathematics of set partitions linearized to (Hilbert) vector spaces. [Preprint]

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

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V. Vilasini and Roger Colbeck

Tue Sep 06 2022 18:00:00 (3 days)

# 12.

Author(s): V. Vilasini and Roger Colbeck

Causality is fundamental to science, but it appears in several different forms. One is relativistic causality, which is tied to a spacetime structure and forbids signaling outside the future. A second is an operational notion of causation that considers the flow of information between physical syste…

[Phys. Rev. Lett. 129, 110401] Published Tue Sep 06, 2022

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Mon Sep 05 2022 05:40:21 (5 days)

# 13.

Vassallo, Antonio and Naranjo, Pedro and Koslowski, Tim (2022) A Proposal for a Metaphysics of Self-Subsisting Structures. I. Classical Physics. Synthese, 200. ISSN 1573-0964

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Sun Sep 04 2022 07:14:49 (6 days)

# 14.

Manchak, JB and Barrett, Thomas William (2022) A Hierarchy of Spacetime Symmetries: Holes to Heraclitus. [Preprint]

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Sat Sep 03 2022 04:43:21 (1 week)

# 15.

Hubert, Mario (2022) Review of Alyssa Ney’s The World in the Wave Function: A Metaphysics for Quantum Physics. [Preprint]

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Thu Sep 01 2022 15:28:24 (1 week)

# 16.

Gao, Shan (2022) Can Bohmian brains make minds? On shadows, puppets and zombies. [Preprint]

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

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Hippolyte Dourdent, Alastair A. Abbott, Nicolas Brunner, Ivan Šupić, and Cyril Branciard

Wed Aug 24 2022 18:00:00 (2 weeks)

# 17.

Author(s): Hippolyte Dourdent, Alastair A. Abbott, Nicolas Brunner, Ivan Šupić, and Cyril Branciard

While the standard formulation of quantum theory assumes a fixed background causal structure, one can relax this assumption within the so-called process matrix framework. Remarkably, some processes, termed causally nonseparable, are incompatible with a definite causal order. We explore a form of cer…

[Phys. Rev. Lett. 129, 090402] Published Wed Aug 24, 2022