Weekly Papers on Quantum Foundations (9)

下午12:05 | Erickson Tjoa, Eduardo Martín-Martínez | quant-ph updates on arXiv.org

We investigate vacuum entanglement harvesting in the presence of a zero mode. We show that, for a variety of detector models and couplings (namely, Unruh-DeWitt qubit and harmonic oscillator detectors, amplitude and derivative coupling), the results are strongly dependent on the state of the zero mode, revealing a strong ambiguity in studies of entanglement harvesting with Neumann or periodic boundary conditions, or in general in spacetimes with toroidal topologies.

Here it is shown that the simplest description of Bell’s experiment according to the canon of von Neumann’s theory of measurement explicitly assumes the (Quantum Mechanics-language equivalent of the classical) condition of Locality. This result is complementary to a recently published one demonstrating that non-Locality is necessary to describe said experiment within the framework of classical hidden variables theories, but that it is unnecessary to describe it within the framework of Quantum Mechanics. Summing up these and other related results, it is concluded that, within the framework of Quantum Mechanics, there is absolutely no reason to believe in the existence of non-Local effects. In addition to its foundational significance, this conclusion has practical impact in the fields of quantum-certified and device-independent randomness generation and on the security of Quantum Key Distribution schemes using entangled states.

下午12:05 | Jonathan Barrett, Robin Lorenz, Ognyan Oreshkov | quant-ph updates on arXiv.org

We present an extension of the framework of quantum causal models to cyclic causal structures. This offers a novel causal perspective on processes beyond those corresponding to standard circuits, such as processes with dynamical causal order and causally nonseparable processes, including processes that violate causal inequalities. We illustrate the concept with examples of well known causally nonseparable processes. We show that for any directed graph, if a process arises from a unitary process with corresponding causal structure by marginalizing over latent local disturbances, then the process is Markov for that graph. As an application of the approach, we present a more fine-grained compositional structure of processes such as the quantum SWITCH, which makes the paths of causal influence and information flow graphically evident. Employing this compositional structure, we show that all unitarily extendible bipartite processes are causally separable, with their unitary extensions realizable via coherent control of the order of operations. Finally, we shown that for unitary processes, causal nonseparability is equivalent to the cyclicity of their causal structure.

下午12:05 | Tsubasa Takagi, Hiroki Hoshina, Masatomi Iizawa, Satoru Saito | quant-ph updates on arXiv.org

To deepen the understanding of quantum field theory (QFT), we elucidate logic of QFT. We assert that logic of QFT should be described by dynamic logic, because the nature of two fundamental operators in QFT, namely creation and annihilation operators, is dynamic in the sense of logic. After we formulate dynamic logic of QFT, we give a dynamic logical interpretation of fermions, the so-called vacuum state, the zero vector and propagators in QFT. Finally, we show how Aharonov-Bohm effect can be explained naturally from our dynamic logic of QFT. This paper should be the beginning of studying logic of QFT from a dynamic point of view.

Authors: Armin TavakoliNicolas Gisin

The Platonic solids is the name traditionally given to the five regular convex polyhedra, namely the tetradron, the octahedron, the cube, the icosahedron and the dodecahedron. Perhaps strongly boosted by the towering historical influence of their namesake, these beautiful solids have, in well over two millenia, transcended traditional boundaries and entered the stage in a range of disciplines. Examples include natural philosophy and mathematics from classical antiquity, scientific modeling during the days of the european scientific revolution and visual arts ranging from the renaissance to modernity. Motivated by mathematical beauty and a rich history, we consider the Platonic solids in the context of modern quantum mechanics. Specifically, we construct Bell inequalities whose maximal violations are achieved with measurements pointing to the vertices of the Platonic solids. These Platonic Bell inequalities are constructed only by inspecting the visible symmetries of the Platonic solids. We also construct Bell inequalities for more general polyhedra and find a Bell inequality that is more robust to noise than the celebrated Clauser-Horne-Shimony-Holt Bell inequality. Finally, we elaborate on the tension between mathematical beauty, which was our initial motivation, and experimental friendliness, which is necessary in all empirical sciences.

Authors: I. Kharuk

We introduce a novel model of affine gravity, which implements the no-scale scenario. Namely, Planck mass and Hubble constant emerge dynamically, through the mechanism of spontaneous breaking of scale-invariance. Moreover, in our model the time direction and non–degenerate metric emerge dynamically as well. This naturally gives rise to the inflation and may server as a starting point for the “birth” of the Universe. We show that our model is phenomenologically viable, both from the perspective of the direct tests of gravity and cosmological evolution.

Authors: Noah BenjaminWill McDermottIva Stavrov Allen

The non-linearity of general relativity makes it at least difficult if not impossible to view a relativistic cloud of matter as being made up of point-source constituents. Perhaps the most delicate issue to circumnavigate is the inherent lack of the classical notion of superposition. Even if one were to believe that the recent framework developed by the first and the third author leads to an appropriate interpretation of the phrase initial data for a point-source, there is prima facie no reason to believe that it lends itself to a principle of superposition. In this paper we propose an extension of said framework which serves as a de-facto superposition of point-sources and which recovers Brill-Lindquist metrics in the limit. We also show that our proposal can be seen as a continuous extension of the classical superposition principle of Newtonian gravity. This paper fits within a larger program of representing relativistic clouds of matter as cumulative effects of point-sources.

Abstract

In this paper I consider the question of whether absolute discernibility is attainable in symmetric languages. Simon Saunders has proven that all facts expressible in first-order language with identity can be equivalently stated within its symmetric sublanguage. I use this result to show specifically how particles of the same type can be absolutely discerned in the permutation-invariant language of the quantum theory of many particles.

2020年2月28日 星期五 下午3:52 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Evans, Peter W. (2020) Perspectival Objectivity or: How I Learned to Stop Worrying and Love Observer-Dependent Reality. [Preprint]
2020年2月27日 星期四 下午6:19 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
McCoy, C.D. (2020) Interpretive Analogies Between Quantum and Statistical Mechanics. European Journal for Philosophy of Science, 10. ISSN 1879-4912
2020年2月27日 星期四 下午6:17 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Kryukov, Alexey (2000) Measurement in classical and quantum physics. [Preprint]
2020年2月27日 星期四 下午6:04 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Cartwright, Nancy and Pemberton, John M. and Wieten, Sarah (2020) Mechanisms, laws and explanation. [Preprint]
2020年2月27日 星期四 下午6:01 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
McCoy, C.D. (2020) An Alternative Interpretation of Statistical Mechanics. Erkenntnis, 85 (1). pp. 1-21. ISSN 0165-0106
2020年2月27日 星期四 上午11:53 | Art Hobson | quant-ph updates on arXiv.org

An argument first proposed by John von Neumann shows that measurement of a superposed quantum system creates an entangled “measurement state” (MS) in which macroscopically distinct detector states appear to be superposed, a paradoxical prediction implying the measurement has no definite outcome. We argue that this prediction is based on a misunderstanding of what the MS represents. We show, by studying the phase dependence of entangled photon states generated in parametric down conversion, that the MS represents not a superposition of detector states, but rather a superposition of coherent (i.e. phase-dependent) correlations between detector states and system states. In fact an argument by Einstein shows that a nonlocal entangled state is required, at least briefly, following a quantum system’s interaction with a detector. Such a state does not represent a paradoxical macroscopic superposition. This resolves the paradox of indefinite outcomes of measurements.

2020年2月27日 星期四 上午11:53 | Yago P. Porto-Silva, Marcos C. de Oliveira | quant-ph updates on arXiv.org

We show that, in the relativistic limit, the quantum theory of neutrino oscillations can be described through the theory of weak measurements with pre and post-selection. The weak nature of neutrino detection allows simultaneous determination of flavor and energy without problems related to the collapse of the wavefunction. Together with post-selection, a non-trivial quantum interference emerges, allowing one to describe a flavor neutrino as one single particle, despite its superposition of masses. We write down the flavor equation of motion and calculate the flavor oscillation probability by showing precisely how a single neutrino interferes with itself.

2020年2月27日 星期四 上午11:53 | Yosuke Morimoto | quant-ph updates on arXiv.org

Using the known duality between events and states, we establish the fact that there is a duality between quantization of events and measurement of states. With this duality, we will show a generalized system of imprimitivity and a covariant measurement are in a dual relation. We also propose a novel quantization scheme as a dual of a measurement model.

2020年2月27日 星期四 上午11:53 | gr-qc updates on arXiv.org

Authors: Pavel KrtoušAndrei Zelnikov

We study a system of two charged non-rotating black holes separated by a strut. Using the exact solution of the Einstein-Maxwell equations, which describes this system, we construct a consistent form of the first law of thermodynamics. We derive thermodynamic parameters related to the strut in an explicit form. The intensive thermodynamical quantity associated with the strut is its tension. We call the corresponding extensive quantity the thermodynamical length and we provide an explicit expression and interpretation for it.

2020年2月27日 星期四 上午8:00 | Liu Y. | The British Journal for the Philosophy of Science Advance Access
Abstract

The notion of comparative probability defined in Bayesian subjectivist theory stems from an intuitive idea that for a given pair of events, one event may be considered ‘more probable’ than the other. Yet it is conceivable that there are cases where it is indeterminate as to which event is more probable, due to, for example, lack of robust statistical information. I take it that these cases involve indeterminate comparative probabilities. This article provides a Savage-style decision-theoretic foundation for indeterminate comparative probabilities.

2020年2月27日 星期四 上午8:00 | Latest Results for Synthese

Abstract

A well-known objection to Humean accounts of laws (e.g. BSA, Lewis in Australas J Philos 61:343–377, 1983, Philosophical papers vol. II, Oxford University Press, 1986) charges them with circularity (Armstrong in What is a law of nature? Cambridge University Press, Cambridge, 1983, p. 102; Maudlin in The metaphysics within physics, Oxford University Press, New York, 2007, p. 172). While the view has it that particular facts explain the natural laws, natural laws are often relied upon in order to explain particular facts. Thus, the Humean is committed to circular explanations—or so goes the argument. In this paper, I review two ways of dealing with the circularity objection against Humean views of laws. Then, by introducing a contrastive treatment of explanations, I put forward a new one, which, if it does not end up dethroning its competitors, I am hoping is still worth exploring.

2020年2月26日 星期三 下午6:00 | Jérôme Martin and Vincent Vennin | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Author(s): Jérôme Martin and Vincent Vennin

The continuous spontaneous localization model solves the measurement problem of standard quantum mechanics by coupling the mass density of a quantum system to a white-noise field. Since the mass density is not uniquely defined in general relativity, this model is ambiguous when applied to cosmology….

[Phys. Rev. Lett. 124, 080402] Published Wed Feb 26, 2020

2020年2月25日 星期二 下午6:00 | Fabian Pokorny, Chi Zhang, Gerard Higgins, Adán Cabello, Matthias Kleinmann, and Markus Hennrich | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Author(s): Fabian Pokorny, Chi Zhang, Gerard Higgins, Adán Cabello, Matthias Kleinmann, and Markus Hennrich

The existence of ideal quantum measurements is one of the fundamental predictions of quantum mechanics. In theory, an ideal measurement projects a quantum state onto the eigenbasis of the measurement observable, while preserving coherences between eigenstates that have the same eigenvalue. The quest…

[Phys. Rev. Lett. 124, 080401] Published Tue Feb 25, 2020

2020年2月25日 星期二 上午9:00 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Kovacs, David Mark (2020) The oldest solution to the circularity problem for Humeanism about the laws of nature. [Preprint]
2020年2月25日 星期二 上午8:59 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Kastner, Ruth (2020) Why the Quantum Absorber Condition is Not a Light-Tight Box. [Preprint]
2020年2月23日 星期日 下午6:44 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Cei, Angelo (2020) Problems of Electrodynamics. A special relativistic interlude. [Preprint]

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