Weekly Papers on Quantum Foundations (28)

Is the problem of molecular structure just the quantum measurement problem? Foundations of Chemistry (2021)

Sebastian Fortin & Olimpia Lombardi

Abstract

In a recent article entitled “The problem of molecular structure just is the measurement problem”, Alexander Franklin and Vanessa Seifert argue that insofar as the quantum measurement problem is solved, the problems of molecular structure are resolved as well. The purpose of the present article is to show that such a claim is too optimistic. Although the solution of the quantum measurement problem is relevant to how the problem of molecular structure is faced, such a solution is not sufficient to account for the structure of molecules as understood in the field of chemistry.

Qubits are not observers — a no-go theorem. (arXiv:2107.03513v1 [quant-ph])

上午9:32

Časlav Brukner

quant-ph updates on arXiv.org

The relational approach to quantum states asserts that the physical description of quantum systems is always relative to something or someone. In relational quantum mechanics (RQM) it is relative to other quantum systems, in the (neo-)Copenhagen interpretation of quantum theory to measurement contexts, and in QBism to the beliefs of the agents. In contrast to the other two interpretations, in RQM any interaction between two quantum systems counts as a “measurement”, and the terms “observer” and “observed system” apply to arbitrary systems. We show, in the form of a no-go theorem, that in RQM the physical description of a system relative to an observer cannot represent knowledge about the observer in the conventional sense of this term. The problem lies in the ambiguity in the choice of the basis with respect to which the relative states are to be defined in RQM. In interpretations of quantum theory where observations play a fundamental role, the problem does not arise because the experimental context defines a preferred basis.

Bose-Einstein condensates in microgravity and fundamental tests of gravity. (arXiv:2107.03709v1 [quant-ph])

上午9:32

Christian Ufrecht, Albert Roura, Wolfgang P. Schleich

quant-ph updates on arXiv.org

Light-pulse atom interferometers are highly sensitive to inertial and gravitational effects. As such they are promising candidates for tests of gravitational physics. In this article the state-of-the-art and proposals for fundamental tests of gravity are reviewed. They include the measurement of the gravitational constant $G$, tests of the weak equivalence principle, direct searches of dark energy and gravitational-wave detection. Particular emphasis is put on long-time interferometry in microgravity environments accompanied by an enormous increase of sensitivity. In addition, advantages as well as disadvantages of Bose-Einstein condensates as atom sources are discussed.

A Quantum Engineer’s Guide to Superconducting Qubits. (arXiv:1904.06560v5 [quant-ph] UPDATED)

上午9:32

Philip Krantz, Morten Kjaergaard, Fei Yan, Terry P. Orlando, Simon Gustavsson, William D. Oliver

quant-ph updates on arXiv.org

The aim of this review is to provide quantum engineers with an introductory guide to the central concepts and challenges in the rapidly accelerating field of superconducting quantum circuits. Over the past twenty years, the field has matured from a predominantly basic research endeavor to one that increasingly explores the engineering of larger-scale superconducting quantum systems. Here, we review several foundational elements — qubit design, noise properties, qubit control, and readout techniques — developed during this period, bridging fundamental concepts in circuit quantum electrodynamics (cQED) and contemporary, state-of-the-art applications in gate-model quantum computation.

Cellular automata in operational probabilistic theories. (arXiv:1911.11216v4 [quant-ph] UPDATED)

上午9:32

Paolo Perinotti

quant-ph updates on arXiv.org

The theory of cellular automata in operational probabilistic theories is developed. We start introducing the composition of infinitely many elementary systems, and then use this notion to define update rules for such infinite composite systems. The notion of causal influence is introduced, and its relation with the usual property of signalling is discussed. We then introduce homogeneity, namely the property of an update rule to evolve every system in the same way, and prove that systems evolving by a homogeneous rule always correspond to vertices of a Cayley graph. Next, we define the notion of locality for update rules. Cellular automata are then defined as homogeneous and local update rules. Finally, we prove a general version of the wrapping lemma, that connects CA on different Cayley graphs sharing some small-scale structure of neighbourhoods.

Wave-particle duality and the objectiveness of “true” and “false”. (arXiv:2009.07027v2 [quant-ph] UPDATED)

上午9:32

Arkady Bolotin

quant-ph updates on arXiv.org

The traditional analysis of the basic version of the double-slit experiment leads to the conclusion that wave-particle duality is a fundamental fact of nature. However, such a conclusion means to imply that we are not only required to have two contradictory pictures of reality but also compelled to abandon the objectiveness of the truth values, “true” and “false”. Yet, even if we could accept wave-like behavior of quantum particles as the best explanation for the build-up of an interference pattern in the double-slit experiment, without the objectivity of the truth values we would never have certainty regarding any statement about the world. The present paper discusses ways to reconcile the correct description of the double-slit experiment with the objectiveness of “true” and “false”.

Remark on using quantum states prepared by the adiabatic quantum computation. (arXiv:2107.01743v2 [quant-ph] UPDATED)

上午9:32

Kazuto Oshima

quant-ph updates on arXiv.org

We indicate that there are points to keep in mind in utilizing quantum states prepared by the adiabatic quantum computation. Even if an instantaneous expectation value of a physical quantity for the adiabatically prepared quantum state is close to an expectation value for the true vacuum, this does not assure us that the prepared vacuum is close to the true vacuum. In general time average of the expectation value tend to systematically differ from the true value. Using a simple model we discuss how to diminish this systematic difference.

European Longitude Prizes. III. The Unsolved Mystery of an Alleged Venetian Longitude Prize. (arXiv:2107.03613v1 [physics.hist-ph])

上午9:32

physics.hist-ph updates on arXiv.org

Authors: Richard de Grijs (Macquarie University, Sydney, Australia)

Despite frequent references in modern reviews to a seventeenth-century Venetian longitude prize, only a single, circumstantial reference to the alleged prize is known from contemporary sources. Edward Harrison’s scathing assessment of the conditions governing the award of an alleged Venetian longitude prize simultaneously disparages the rewards offered by the Dutch States General. However, the latter had long run its course by 1696, the year of the citation, thus rendering Harrison’s reference unreliable. Whereas other longitude awards offered by the leading European maritime nations attracted applicants from far and wide, often accompanied by extensive, self-published pamphlets, the alleged Venetian prize does not seem to have been subject to similar hype. The alleged existence of seventeenth-century Venetian award is particularly curious, because the city’s fortune was clearly in decline, and longitude determination on the open seas does not appear to have been a priority; the city’s mariners already had access to excellent “portolan” charts. It is therefore recommended that authors refrain from referring to a potentially phantom Venetian longitude prize in the same context as the major sixteenth- to eighteenth-century European awards offered by the dominant sea-faring nations.

Degrees of riskiness, falsifiability, and truthlikeness. A neo-Popperian account applicable to probabilistic theories. (arXiv:2107.03772v1 [physics.hist-ph])

上午9:32

physics.hist-ph updates on arXiv.org

Authors: Leander Vignero, Sylvia Wenmackers

In this paper, we take a fresh look at three Popperian concepts: riskiness, falsifiability, and truthlikeness (or verisimilitude) of scientific hypotheses or theories. First, we make explicit the dimensions that underlie the notion of riskiness. Secondly, we examine if and how degrees of falsifiability can be defined, and how they are related to various dimensions of the concept of riskiness as well as the experimental context. Thirdly, we consider the relation of riskiness to (expected degrees of) truthlikeness. Throughout, we pay special attention to probabilistic theories and we offer a tentative, quantitative account of verisimilitude for probabilistic theories.

Truth and reality: How to be a scientific realist without believing scientific theories should be true

上午3:03

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

Potochnik, Angela (2021) Truth and reality: How to be a scientific realist without believing scientific theories should be true. [Preprint]

Approaching probabilistic laws

2021年7月9日星期五上午8:00

Latest Results for Synthese

Abstract

In the general problem of verisimilitude, we try to define the distance of a statement from a target, which is an informative truth about some domain of investigation. For example, the target can be a state description, a structure description, or a constituent of a first-order language (Sect. 1). In the problem of legisimilitude, the target is a deterministic or universal law, which can be expressed by a nomic constituent or a quantitative function involving the operators of physical necessity and possibility (Sect. 2). The special case of legisimilitude, where the target is a probabilistic law (Sect. 3), has been discussed by Roger Rosenkrantz (Synthese, 1980) and Ilkka Niiniluoto (Truthlikeness, 1987, Ch. 11.5). Their basic proposal is to measure the distance between two probabilistic laws by the Kullback–Leibler notion of divergence, which is a semimetric on the space of probability measures. This idea can be applied to probabilistic laws of coexistence and laws of succession, and the examples may involve discrete or continuous state spaces (Sect. 3). In this paper, these earlier studies are elaborated in four directions (Sect. 4). First, even though deterministic laws are limiting cases of probabilistic laws, the target-sensitivity of truthlikeness measures implies that the legisimilitude of probabilistic laws is not easily reducible to the deterministic case. Secondly, the Jensen-Shannon divergence is applied to mixed probabilistic laws which entail some universal laws. Thirdly, a new class of distance measures between probability distributions is proposed, so that their horizontal differences are taken into account in addition to vertical ones (Sect. 5). Fourthly, a solution is given for the epistemic problem of estimating degrees of probabilistic legisimilitude on the basis of empirical evidence (Sect. 6).

Formulations of Classical Mechanics

2021年7月8日星期四下午12:36

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North, Jill (2019) Formulations of Classical Mechanics. [Preprint]

Is Electromagnetic Field Momentum Due to the Flow of Field Energy?

2021年7月8日星期四上午5:43

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Johns, Oliver Davis (2021) Is Electromagnetic Field Momentum Due to the Flow of Field Energy? [Preprint]

Can machines think? The controversy that led to the Turing test, 1946-1950

2021年7月8日星期四上午5:43

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Gonçalves, Bernardo (2021) Can machines think? The controversy that led to the Turing test, 1946-1950. [Preprint]