Weekly Papers on Quantum Foundations (21)

A no-go result for Bohmian mechanics

2022年5月19日 星期四 上午1:29|Philsci-Archive: No conditions. Results ordered -Date Deposited.

Gao, Shan (2022) A no-go result for Bohmian mechanics. [Preprint]

From Unobservable to Observable: Scientific Realism and the Discovery of Radium

2022年5月19日 星期四 上午1:28|Philsci-Archive: No conditions. Results ordered -Date Deposited.

Allzén, Simon (2022) From Unobservable to Observable: Scientific Realism and the Discovery of Radium. Journal for General Philosophy of Science. ISSN 0925-4560

A Discrete Analog of General Covariance — Part 2: Despite what you’ve heard, a perfectly Lorentzian lattice theory

2022年5月19日 星期四 上午1:27|Philsci-Archive: No conditions. Results ordered -Date Deposited.

Grimmer, Daniel (2022) A Discrete Analog of General Covariance — Part 2: Despite what you’ve heard, a perfectly Lorentzian lattice theory. [Preprint]


2022年5月19日 星期四 上午1:26|Philsci-Archive: No conditions. Results ordered -Date Deposited.

Shkliarevsky, Gennady (2022) THE MIND’S EYE: DE-MYSTIFYING CONSCIOUSNESS. [Preprint]

A Discrete Analog of General Covariance — Part 1: Could the world be fundamentally set on a lattice?

2022年5月19日 星期四 上午1:19|Philsci-Archive: No conditions. Results ordered -Date Deposited.

Grimmer, Daniel (2022) A Discrete Analog of General Covariance — Part 1: Could the world be fundamentally set on a lattice? [Preprint]

Beyond semiclassical time. (arXiv:2205.09147v1 [gr-qc])

上午11:02|Leonardo Chataignier|quant-ph updates on arXiv.org

We show that the usual Born-Oppenheimer type of approximation used in quantum gravity, in which a semiclassical time parameter emerges from a weak-coupling expansion of the Wheeler-DeWitt constraint, leads to a unitary theory at least up to the next-to-leading order in minisuperspace models. As there are no unitarity-violating terms, this settles the issue of unitarity at this order, which has been much debated in the literature. Furthermore, we also show that the conserved inner product is gauge-fixed in the sense that the measure is related to the Faddeev-Popov determinant associated with the choice of semiclassical time as a reparametrization gauge. This implies that the Born-Oppenheimer approach to the problem of time is, in fact, an instance of a relational quantum theory, in which transition amplitudes can be related to conditional probabilities.

On the misinterpretation of conditionally-solvable quantum-mechanical problems. (arXiv:2205.07884v2 [quant-ph] UPDATED)

上午11:02|Francisco M. Fernández|quant-ph updates on arXiv.org

We apply the Frobenius (power-series) method to some simple exactly-solvable and conditionally-solvable quantum-mechanical models with supposed physical interest. We show that the supposedly exact solutions to radial eigenvalue equations derived in recent papers are not correct because they do not satisfy some well-known theorems. We also discuss the origin of the mistake by means of the approach indicated above.

The Pragmatic QFT Measurement Problem and the need for a Heisenberg-like Cut in QFT. (arXiv:2205.09608v1 [physics.hist-ph])

上午11:02|physics.hist-ph updates on arXiv.org

Authors: Daniel Grimmer

Despite quantum theory’s remarkable success at predicting the (statistical) results of experiments, many philosophers worry that it nonetheless lacks some crucial connection between theory and experiment. Such worries are at the root of the Quantum Measurement Problem. We can identify two kinds of worries: 1) pragmatic: it’s unclear how to model our experiments to extract theoretical predictions, and 2) realist: there is no realist narrative for the experiment underlying these theoretical predictions. While both worries deserve attention, the pragmatic worries have far worse consequences if left unanswered. Moreover, as I will argue, upon reflection, a satisfactory explanation of almost all of quantum theory’s experimental successes unavoidably involves modeling quantum fields at some point. Thus, without a pragmatic theory-to-experiment link for QFT, we are at risk of losing any right to claim evidential support for large parts of quantum theory. Hence, I focus on the Pragmatic QFT Measurement Problem.

But, what makes modeling measurements in QFT so hard? As I will discuss, attempts to naively transplant our non-relativistic quantum measurement theory into QFT are deeply unphysical and unsatisfying. Thus we need a new (or at least refined) measurement theory for QFT. However, as I will argue, aiming too directly at a new measurement theory is an incautious way to proceed and is apt to lead us astray. This paper proposes an alternate way forward: We ought to first better understand how our non-relativistic quantum measurement theory is rooted in notions of measurement chains and Heisenberg cuts. Then we ought to generalize these notions and transplant them into QFT. Such a transplant is carried out in this paper. My analysis suggests the need for a pragmatic QFT-cut analogous to the need for a pragmatic Heisenberg cut in non-relativistic contexts.

Demonstration of weak measurements, projective measurements, and quantum-to-classical transitions in ultrafast free electron-photon interactions. (arXiv:1910.11685v3 [quant-ph] UPDATED)

上午11:02|physics.hist-ph updates on arXiv.org

Authors: Yiming PanEliahu CohenEbrahim KarimiAvraham GoverNorbert SchonenbergerTomas ChloubaKangpeng WangSaar NehemiaPeter HommelhoffIdo KaminerYakir Aharonov

How does the quantum-to-classical transition of measurement occur? This question is vital for both foundations and applications of quantum mechanics. Here, we develop a new measurement-based framework for characterizing the classical and quantum free electron-photon interactions and then experimentally test it. We first analyze the transition from projective to weak measurement in generic light-matter interactions and show that any classical electron-laser-beam interaction can be represented as an outcome of a weak measurement. In particular, the appearance of classical point-particle acceleration is an example of an amplified weak value resulting from weak measurement. A universal factor quantifies the measurement regimes and their transition from quantum to classical, where Gamma corresponds to the ratio between the electron wavepacket size and the optical wavelength. This measurement-based formulation is experimentally verified in both limits of photon-induced near-field electron microscopy and the classical acceleration regime using a dielectric laser accelerator. Our results shed new light on the transition from quantum to classical electrodynamics, enabling to employ the essence of wave-particle duality of both light and electrons in quantum measurement for exploring and applying many quantum and classical light-matter interactions.

Way down in the hole… and up again. (arXiv:2205.09610v1 [gr-qc])

上午11:02|gr-qc updates on arXiv.org

Authors: Valentin Boyanov

I argue that an approach which uses an appropriate admixture of both classical and semiclassical effects is essential for understanding the ultimate fate of gravitational collapse and the nature of black holes. I provide an example of a problem which pushes the boundaries of what is known in both the classical and semiclassical approaches: the evolution of the inner horizon of a black hole. I show that solving this problem requires considering perturbations of both classical and semiclassical origin. In fact, it has been found that classical mass inflation might be counteracted by a semiclassical tendency for the inner horizon to inflate outward.

Energy and entropy in the Geometrical Trinity of gravity. (arXiv:2205.09716v1 [gr-qc])

上午11:02|gr-qc updates on arXiv.org

Authors: Débora Aguiar GomesJose Beltrán JiménezTomi S. Koivisto

All energy is gravitational energy. That is the consequence of the equivalence principle, according to which gravity is the universal interaction. The physical charges of this interaction have remained undisclosed, but the Adventof the Geometrical Trinity opened a new approach to this foundational problem. Here it is shown to provide a background-independent unification of the previous, non-covariant approaches of Bergmann-Thomson, Cooperstock, Einstein, von Freud, Landau-Lifshitz, Papapetrou and Weinberg. First, the Noether currents are derived for a generic Palatini theory of gravity coupled with generic matter fields, and then the canonical i.e. the unique charges are robustly derived and analysed, particularly in the metric teleparallel and the symmetric teleparallel versions of General Relativity. These results, and their application to black holes and gravitational waves, are new.

Time delay interferometry without clock synchronisation. (arXiv:2202.01124v3 [gr-qc] UPDATED)

上午11:02|gr-qc updates on arXiv.org

Authors: Olaf HartwigJean-Baptiste BayleMartin StaabAurélien HeesMarc LilleyPeter Wolf

Time-delay interferometry (TDI) is a data processing technique for LISA designed to suppress the otherwise overwhelming laser noise by several orders of magnitude. It is widely believed that TDI can only be applied once all phase or frequency measurements from each spacecraft have been synchronized to a common time frame. We demonstrate analytically, using as an example the commonly-used Michelson combination X, that TDI can be computed using the raw, unsynchronized data, thereby avoiding the need for an initial synchronization processing step and significantly simplifying the initial noise reduction pipeline. Furthermore, the raw data is free of any potential artifacts introduced by clock synchronization and reference frame transformation algorithms, which allows to operate directly on the MHz beatnotes. As a consequence, in-band clock noise is directly suppressed as part of TDI, in contrast to the approach previously proposed in the literature (in which large trends in the beatnotes are removed before the main laser-noise reduction step, and clock noise is suppressed in an extra processing step). We validate our algorithm with full-scale numerical simulations that use LISA Instrument and PyTDI and show that we reach the same performance levels as the previously proposed methods, ultimately limited by the clock sideband stability.

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