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We present thought experiments to measure the Arnowitt–Deser–Misner E ADM and Bondi–Sachs energy E BS of isolated systems in general relativity. The expression of E BS used in the protocol is likely to have other applications. In particular, it is well-suited to be promoted to an operator in non-perturbative loop quantum gravity. [ABSTRACT FROM AUTHOR]

Compared to traditional swell height measurement methods, spaceborne global navigation satellite system reflectometry (GNSS-R) has many advantages, including remote sensing capabilities, global coverage, real-time monitoring, etc. It can provide wave observation data with high spatiotemporal resolution and is not limited by time, weather, and other conditions. Spaceborne GNSS-R provides a very effective method for estimating swell height, which can monitor and measure wave changes over a large area of the ocean surface in real time. This is of great significance for understanding the marine environment, climate change, and weather forecasting. However, there is relatively little research on the estimation of swell height using this technology, especially in the retrieval model of swell height. For this purpose, the article proposes a global ocean swell height retrieval method based on the convolutional neural network (CNN), convolutional long short-term memory (ConvLSTM) and fully connected network (FCN) hybrid deep learning model (i.e., CNN-ConvLSTM-FCN) for spaceborne GNSS-R. CNN-ConvLSTM-FCN model not only uses CNN to extract spatial features around specular points (SPs) from a two-dimensional (2-D) matrix of a single image (bistatic radar scattering cross-section (BRCS), effective scattering area, or power delay-Doppler map (DDM), but also uses ConvLSTM network to infer feature relationships and FCN to output estimated swell heights. The hybrid model improves its retrieval ability by simultaneously considering feature information related to time and space. The performance of the CNN-ConvLSTM-FCN model in retrieving swell height was tested using ERA5 and WaveWatch III swell height as reference data. The results show that when ERA5 data is used as a reference, compared to the empirical model method based on DDM average (DDMA) observable, the proposed CNN-ConvLSTM-FCN swell height retrieval model improves root mean square error (RMSE), correlation coefficient (CC), and mean absolute percentage error (MAPE) by 50.76%, 26.28%, and 29.63%, respectively. When WaveWatch III data is used as a reference, improvements in RMSE, CC, and MAPE are 51.09%, 25.35%, and 44.21%, respectively. The CNN-ConvLSTM-FCN model can demonstrate the ability of high-precision and high-resolution ocean swell height retrieval on a global scale, providing a new reference method for spaceborne GNSS-R ocean swell height estimation. [ABSTRACT FROM AUTHOR]

We present thought experiments to measure the Arnowitt–Deser–Misner EADM and Bondi–Sachs energy EBS of isolated systems in general relativity. The expression of EBS used in the protocol is likely to have other applications. In particular, it is well-suited to be promoted to an operator in non-perturbative loop quantum gravity.

We review, under a modern light, the conditions that render the Boltzmann equation applicable. These are conditions that permit probability to behave like mass, thereby possessing clear and concrete content, whereas generally, this is not the case. Because science and technology are increasingly interested in small systems that violate the conditions of the Boltzmann equation, probability appears to be the only mathematical tool suitable for treating them. Therefore, Boltzmann's teachings remain relevant, and the present analysis provides a critical perspective useful for accurately interpreting the results of current applications of statistical mechanics. [ABSTRACT FROM AUTHOR]

The exact, non perturbative, response theory developed within the field of non-equilibrium molecular dynamics, also known as TTCF (transient time correlation function), applies to quite general dynamical systems. Its key element is called the dissipation function because it represents the power dissipated by external fields acting on the particle system of interest, whose coupling with the environment is given by deterministic thermostats. This theory has been initially developed for time-independent external perturbations, and then it has been extended to time-dependent perturbations. It has also been applied to dynamical systems of different nature, and to oscillator models undergoing phase transitions, which cannot be treated with, e.g., linear response theory. The present work includes time-dependent stochastic perturbations in the theory using the Karhunen–Loève theorem. This leads to three different investigations of a given process. In the first, a single realization of the stochastic coefficients is fixed, and averages are taken only over the initial conditions, as in a deterministic process. In the second, the initial condition is fixed, and averages are taken with respect to the distribution of stochastic coefficients. In the last investigation, one averages over both initial conditions and stochastic coefficients. We conclude by illustrating the applicability of the resulting exact response theory with simple examples. [ABSTRACT FROM AUTHOR]

This paper is devoted to clarification of the notion of entanglement through decoupling it from the tensor product structure and treating as a constraint posed by probabilistic dependence of quantum observable A and B. In our framework, it is meaningless to speak about entanglement without pointing to the fixed observables A and B, so this is AB-entanglement. Dependence of quantum observables is formalized as non-coincidence of conditional probabilities. Starting with this probabilistic definition, we achieve the Hilbert space characterization of the AB-entangled states as amplitude non-factorisable states. In the tensor product case, AB-entanglement implies standard entanglement, but not vise verse. AB-entanglement for dichotomous observables is equivalent to their correlation, i.e., ⟨ A B ⟩ ψ ≠ ⟨ A ⟩ ψ ⟨ B ⟩ ψ. We describe the class of quantum states that are A u B u -entangled for a family of unitary operators (u). Finally, observables entanglement is compared with dependence of random variables in classical probability theory. [ABSTRACT FROM AUTHOR]

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 constitute the Quantum Measurement Problems. One can broadly identify two kinds of worries: (1) pragmatic: it is unclear how to model our measurement processes in order to extract experimental predictions, and (2) realist: we lack a satisfying metaphysical account of measurement processes. While both issues deserve attention, the pragmatic worries have worse consequences if left unanswered: If our pragmatic theory-to-experiment linkage is unsatisfactory, then quantum theory is at risk of losing both its evidential support and its physical salience. Avoiding these risks is at the core of what I will call the Pragmatic Measurement Problem. Fortunately, the pragmatic measurement problem is not too difficult to solve. For non-relativistic quantum theory, the story goes roughly as follows: One can model each of quantum theory’s key experimental successes on a case-by-case basis by using a measurement chain. In modeling this measurement chain, it is pragmatically necessary to switch from using a quantum model to a classical model at some point. That is, it is pragmatically necessary to invoke a Heisenberg cut at some point along the measurement chain. Past this case-by-case measurement framework, one can then strive for a wide-scoping measurement theory capable of modeling all (or nearly all) possible measurement processes. For non-relativistic quantum theory, this leads us to our usual projective measurement theory. As a bonus, proceeding this way also gives us an empirically meaningful characterization of the theory’s observables as (positive) self-adjoint operators. But how does this story have to change when we move into the context of quantum field theory (QFT)? It is well known that in QFT almost all localized projective measurements violate causality, allowing for faster-than-light signaling; These are Sorkin’s impossible measurements. Thus, the story of measurement in QFT cannot end as it did before with a projective measurement theory. But does this then mean that we need to radically rethink the way we model measurement processes in QFT? Are our current experimental practices somehow misguided? Fortunately not. I will argue that (once properly understood) our old approach to modeling quantum measurements is still applicable in QFT contexts. We ought to first use measurement chains to build up a case-by-case measurement framework for QFT. Modeling these measurement chains will require us to invoke what I will call a QFT-cut. That is, at some point along the measurement chain we must switch from using a QFT model to a non-QFT model. Past this case-by-case measurement framework, we can then strive for both a new wide-scoping measurement theory for QFT and an empirically meaningful characterization of its observables. It is at this point that significantly more theoretical work is needed. This paper ends by briefly reviewing the state of the art in the physics literature regarding the modeling of measurement processes involving quantum fields. [ABSTRACT FROM AUTHOR]

We first define the coarse-graining of probability measures in terms of stochastic kernels. We define when a probability measure is part of another probability measure and say that two probability measures coexist if they are both parts of a single probability measure. We then show that any two probability measures coexist. We extend these concepts to observables and instruments and mention that two observables need not coexist. We define the discretization of an observable as a special case of coarse-graining and show that these have 0–1 stochastic kernels. We next consider finite observables and instruments and show that in these cases, stochastic kernels are replaced by stochastic matrices. We also show that coarse-graining is the same as post-processing in this finite case. We then consider sequential products of observables and discuss the sequential product of a post-processed observable with another observable. We briefly discuss SIC observables and the example of qubit observables.

We review, under a modern light, the conditions that render the Boltzmann equation applicable. These are conditions that permit probability to behave like mass, thereby possessing clear and concrete content, whereas generally, this is not the case. Because science and technology are increasingly interested in small systems that violate the conditions of the Boltzmann equation, probability appears to be the only mathematical tool suitable for treating them. Therefore, Boltzmann’s teachings remain relevant, and the present analysis provides a critical perspective useful for accurately interpreting the results of current applications of statistical mechanics.

The exact, non perturbative, response theory developed within the field of non-equilibrium molecular dynamics, also known as TTCF (transient time correlation function), applies to quite general dynamical systems. Its key element is called the dissipation function because it represents the power dissipated by external fields acting on the particle system of interest, whose coupling with the environment is given by deterministic thermostats. This theory has been initially developed for time-independent external perturbations, and then it has been extended to time-dependent perturbations. It has also been applied to dynamical systems of different nature, and to oscillator models undergoing phase transitions, which cannot be treated with, e.g., linear response theory. The present work includes time-dependent stochastic perturbations in the theory using the Karhunen–Loève theorem. This leads to three different investigations of a given process. In the first, a single realization of the stochastic coefficients is fixed, and averages are taken only over the initial conditions, as in a deterministic process. In the second, the initial condition is fixed, and averages are taken with respect to the distribution of stochastic coefficients. In the last investigation, one averages over both initial conditions and stochastic coefficients. We conclude by illustrating the applicability of the resulting exact response theory with simple examples.

We consider the question as to whether a quantum system is uniquely determined by all values of all its observables. For this, we consider linearly nuclear GB*-algebras over W*-algebras as models of quantum systems. [ABSTRACT FROM AUTHOR]

We investigate the onset of magnetic reconnection, utilizing a fully kinetic Particle‐In‐Cell (PIC) simulation. Characteristic features of the electron phase‐space distributions immediately before reconnection onset are identified. These include signatures of pressure non‐gyrotropy in the velocity distributions, and lemon shaped distributions in the in‐plane velocity directions. Further, we explain how these features form through particle energization by the out‐of‐plane electric field. Identification of these features in the distributions can aid in analysis of data where clear signatures of ongoing reconnection are not yet present. Plain Language Summary: In any environment where magnetic fields and charged particles interact, magnetic reconnection will occur if the conditions are favorable. Magnetic reconnection can be described as magnetic explosions, since it releases stored magnetic energy and converts it into heat and movement of the plasma particles. In this paper, we use numerical simulations to take a closer look at how the reconnection process initiates, a fundamental question still not fully understood. Key Points: Signatures indicating reconnection onset can be identified in the electron distributionsOnset signatures persist over extended spatial and temporal scalesThe particle distributions immediately preceding onset are characterized by features of non‐gyrotropy and acceleration [ABSTRACT FROM AUTHOR]

We first define the coarse-graining of probability measures in terms of stochastic kernels. We define when a probability measure is part of another probability measure and say that two probability measures coexist if they are both parts of a single probability measure. We then show that any two probability measures coexist. We extend these concepts to observables and instruments and mention that two observables need not coexist. We define the discretization of an observable as a special case of coarse-graining and show that these have 0 –1 stochastic kernels. We next consider finite observables and instruments and show that in these cases, stochastic kernels are replaced by stochastic matrices. We also show that coarse-graining is the same as post-processing in this finite case. We then consider sequential products of observables and discuss the sequential product of a post-processed observable with another observable. We briefly discuss SIC observables and the example of qubit observables. [ABSTRACT FROM AUTHOR]

We consider the question as to whether a quantum system is uniquely determined by all values of all its observables. For this, we consider linearly nuclear GB*-algebras over W*-algebras as models of quantum systems.

The problem of observables and their supposed lack of change has been significant in Hamiltonian quantum gravity since the 1950s. This paper considers the unrecognized variety of ideas about observables in the thought of constrained Hamiltonian dynamics co-founder Peter Bergmann, who trained many students at Syracuse and invented observables. Whereas initially Bergmann required a constrained Hamiltonian formalism to be mathematically equivalent to the Lagrangian, in 1953 Bergmann and Schiller introduced a novel postulate, motivated by facilitating quantum gravity. This postulate held that observables were invariant under transformations generated by each individual first-class constraint. While modern works rely on Bergmann's authority and sometimes speak of "Bergmann observables," he had much to say about observables, generally interesting and plausible but not all mutually consistent and much of it neglected. On occasion he required observables to be locally defined (not changeless and global); at times he wanted observables to be independent of the Hamiltonian formalism (implicitly contrary to a definition involving separate first-class constraints). But typically he took observables to have vanishing Poisson bracket with each first-class constraint and took this result to be justified by the example of electrodynamics. He expected observables to be analogous to the transverse true degrees of freedom of electromagnetism. Given these premises, there is no coherent concept of observables which he reliably endorsed, much less established. A revised definition of observables that satisfies the requirement that equivalent theories should have equivalent observables using the Rosenfeld–Anderson–Bergmann–Castellani gauge generator G , a tuned sum of first-class constraints that changes the canonical action ∫ d t (p q ̇ − H) by a boundary term. Bootstrapping from theory formulations with no first-class constraints, one finds that the "external" coordinate gauge symmetry of GR calls for covariance (a transformation rule and hence a 4-dimensional Lie derivative for the Poisson bracket), not invariance (0 Poisson bracket), under G (not each first-class constraint separately). [ABSTRACT FROM AUTHOR]

The existence of incompatible measurements, i.e. measurements which cannot be performed simultaneously on a single copy of a quantum state, constitutes an important distinction between quantum mechanics and classical theories. While incompatibility might at first glance seem like an obstacle, it turns to be a necessary ingredient to achieve the so-called quantum advantage in various operational tasks like random access codes or key distribution. To improve our understanding of how to quantify incompatibility of quantum measurements, we define and explore a family of incompatibility measures based on non-commutativity. We investigate some basic properties of these measures, we show that they satisfy some natural information-processing requirements and we fully characterize the pairs which achieve the highest incompatibility (in a fixed dimension). We also consider the behavior of our measures under different types of compositions. Finally, to link our new measures to existing results, we relate them to a robustness-based incompatibility measure and two operational scenarios: random access codes and entropic uncertainty relations. [ABSTRACT FROM AUTHOR]

This paper discusses the role of unobservable entities in scientific theories. The science used as example is linguistics. It is not one of the hard sciences and those in them may state that the problem of unobservables does not affect it. I think, however, that the use of linguistics is justified as there are fields in it that are natural sciences or at least closely approach them. I begin by discussing the positivists’ strict distinction between theory and observation and what happens if a theory never goes beyond observation terms and generalizations over them. Then I turn to difficulties raised by this theory/observation distinction. It turns out that a) unobservables are necessary for construction of possible worlds that generate explanations and predictions, b) the distinction between observables and unobservables should be made. I adhere to M W Wartofsky’s and R.Torretti’s view of this distinction with the idea of possible worlds added. The paper ends with an appendix on the generative syntax entity PRO used as example in illustrating the adopted point of view. [ABSTRACT FROM AUTHOR]

Dans la perspective théorique de la Sémantique des Possibles Argumentatifs, l’article s’interroge sur la nature sémantique et le statut épistémologique des observables dans la matérialité du texte, tels qu’ils sont proposés par son traitement informatique : mots, associations de mots, environnements sémantique et syntaxique. La thèse défendue est que l’analyse de ces observables n’épuise pas le sens discursif et qu’elle doit s’appuyer sur une démarche de prise en compte dans l’interprétation du sens non seulement du contexte, mais aussi et surtout de la complexité du potentiel argumentatif des mots. Le corollaire de ce point de vue est une triangulation des méthodologies dans laquelle l’analyse qualitative sémantico-discursive des conceptualisations sémantiques offre un modèle conceptuel au traitement textométrique qu’elle précède.

If a is a quantum effect and ρ is a state, we define the ρ-entropy Sa(ρ) which gives the amount of uncertainty that a measurement of a provides about ρ. The smaller Sa(ρ) is, the more information a measurement of a gives about ρ. In Entropy for Effects, we provide bounds on Sa(ρ) and show that if a+b is an effect, then Sa+b(ρ)≥Sa(ρ)+Sb(ρ). We then prove a result concerning convex mixtures of effects. We also consider sequential products of effects and their ρ-entropies. In Entropy of Observables and Instruments, we employ Sa(ρ) to define the ρ-entropy SA(ρ) for an observable A. We show that SA(ρ) directly provides the ρ-entropy SI(ρ) for an instrument I. We establish bounds for SA(ρ) and prove characterizations for when these bounds are obtained. These give simplified proofs of results given in the literature. We also consider ρ-entropies for measurement models, sequential products of observables and coarse-graining of observables. Various examples that illustrate the theory are provided.

In his 1916 review paper on general relativity, Einstein made the often-quoted oracular remark that all physical measurements amount to a determination of coincidences, like the coincidence of a pointer with a mark on a scale. This argument, which was meant to express the requirement of general covariance, immediately gained great resonance. Philosophers such as Schlick found that it expressed the novelty of general relativity, but the mathematician Kretschmann deemed it as trivial and valid in all spacetime theories. With the relevant exception of the physicists of Leiden (Ehrenfest, Lorentz, de Sitter, and Nordström), who were in epistolary contact with Einstein, the motivations behind the point-coincidence remark were not fully understood. Only at the turn of the 1960s did Bergmann (Einstein's former assistant in Princeton) start to use the term 'coincidence' in a way that was much closer to Einstein's intentions. In the 1980s, Stachel, projecting Bergmann's analysis onto his historical work on Einstein's correspondence, was able to show that what he started to call 'the point-coincidence argument' was nothing but Einstein's answer to the infamous 'hole argument'. The latter has enjoyed enormous popularity in the following decades, reshaping the philosophical debate on spacetime theories. The point-coincidence argument did not receive comparable attention. By reconstructing the history of the argument and its reception, this paper argues that this disparity of treatment is not justified. This paper will also show that the notion that only coincidences are observable in physics marks every critical step of Einstein's struggle with the meaning of coordinates in physics. [ABSTRACT FROM AUTHOR]

After obtaining an exact solution, we study gravitational lensing in strong-field limit by a static spherically symmetric charged black hole immersed in the perfect fluid dark matter (PFDM) having additional parameters β and l , respectively, because of PFDM and nonlinear electrodynamics. We observe a decrease in the deflection angle α D , photon sphere radius x p s , and angular position θ ∞ with parameters l and β , meanwhile the ratio of the flux of the first image to all other images r m a g increases (decreases) with an increasing magnitude of parameter β (l). For Sgr A*, the angular position θ ∞ is ∈ (20. 65 , 51. 52) μ as , while for M87* ∈ (15. 5 , 38. 7) μ as. The angular separation s , for SMBHs Sgr A* ranging ∈ (0. 033 − 6. 93) μ as and for M87* as ∈ (0. 025 − 5. 21) μ as. We observe that the deviation Δ θ ∞ of charged-PFDM black holes from their general relativity (GR) counterpart, for supermassive black holes Sgr A* and M87* (at β = − 0. 01 and l = 0. 1), can reach as much as 1. 28 μ as and 0. 96 μ as , respectively. In comparison, Δ s is about 6.22 nas for Sgr A* and 4.67 nas for M87*. EHT bounds on the θ s h of Sgr A* and M87* within the 1 σ region, bound the parameters β and l , our analysis concludes that the charged-PFDM black holes agree with the EHT results in the finite space. Our results may contribute to a better understanding of dark matter and help find its signature. [ABSTRACT FROM AUTHOR]

In constrained Hamiltonian dynamics there are two views regarding how first-class constraints generate gauge transformations: individually or only in a certain combination, the Rosenfeld–Anderson–Bergmann–Castellani gauge generator. This gauge generator G preserves Hamilton's equations and changes the canonical action at most by a boundary term; Hamiltonian's equations are the Euler–Lagrange equations for the canonical action. Hence the canonical formalism is equivalent to the Lagrangian formalism, and indeed subsumed within it (in important examples) with many canonical momenta serving as auxiliary fields. G generates transformations basically equivalent to the usual 4-dimensional Lagrangian expressions, such as a 4-gradient in electromagnetism or a space–time coordinate transformation (on-shell) in General Relativity. It has been shown recently that separate first-class constraints lead to inequivalent observables between Proca non-gauge and Stueckelberg gauge massive electromagnetism. There is, however, widespread agreement that second-class constraints do not generate gauge transformations. Here it is shown that in such a sense as the first-class primary constraint in Maxwell's theory generates a gauge transformation, the second-class primary constraint in Proca's massive electromagnetism also generates a gauge transformation. Likewise the second-class primary constraints in various massive spin 2 relatives of General Relativity generate as much of a gauge transformation as do the corresponding first-class primary constraints in GR. Hence the view that first-class constraints typically generate gauge transformations individually faces a puzzle not faced by the gauge generator view. [ABSTRACT FROM AUTHOR]

Synaptic algebras, introduced by D. Foulis, generalize different algebraic structures used so far as mathematical models of quantum mechanics: the traditional Hilbert space approach, order unit spaces, Jordan algebras, effect algebras, MV-algebras, orthomodular lattices. We study sharp and fuzzy observables on two special classes of synaptic algebras: on the so called generalized Hermitian algebras and on synaptic algebras which are Banach space duals. Relations between fuzzy and sharp observables on these two types of synaptic algebras are shown. [ABSTRACT FROM AUTHOR]

Asymptotic safety is a theoretical proposal for the ultraviolet completion of quantum field theories, in particular for quantum gravity. Significant progress on this program has led to a first characterization of the Reuter fixed point. Further advancement in our understanding of the nature of quantum spacetime requires addressing a number of open questions and challenges. Here, we aim at providing a critical reflection on the state of the art in the asymptotic safety program, specifying and elaborating on open questions of both technical and conceptual nature. We also point out systematic pathways, in various stages of practical implementation, toward answering them. Finally, we also take the opportunity to clarify some common misunderstandings regarding the program.

We are focused on the idea that observables in quantum physics are a bit more then just hermitian operators and that this is, in general, a “tricky business”. The origin of this idea comes from the fact that there is a subtle difference between symmetric, hermitian, and self-adjoint operators which are of immense importance in formulating Quantum Mechanics. The theory of self-adjoint extensions is presented through several physical examples and some emphasis is given on the physical implications and applications.

We introduce a mathematical formulation of feature-informed data assimilation (FIDA). In FIDA, the information about feature events, such as shock waves, level curves, wavefronts and peak value, in dynamical systems are used for the estimation of state variables and unknown parameters. The observation operator in FIDA is a set-valued functional that involves a search process over a function of state variables, which is fundamentally different from the observation operators in conventional data assimilation. We present three numerical experiments, in which shocks and expanding waves are observed features. These examples serve to demonstrate FIDA's ability to estimate model parameters from such noisy observations. • We introduce a class of inverse problems, referred to as feature-informed data assimilation (FIDA). • Observational data in FIDA are associated with discontinuities or extreme values of a state variable. • Observation operator in FIDA is a nonlinear functional that results in set-valued outputs. • Our experiments show that feature observations carry sufficient information to estimate model parameters. [ABSTRACT FROM AUTHOR]

The exact, non perturbative, response theory developed within the field of non-equilibrium molecular dynamics, also known as TTCF (transient time correlation function), applies to quite general dynamical systems. Its key element is called the dissipation function because it represents the power dissipated by external fields acting on the particle system of interest, whose coupling with the environment is given by deterministic thermostats. This theory has been initially developed for time-independent external perturbations, and then it has been extended to time-dependent perturbations. It has also been applied to dynamical systems of different nature, and to oscillator models undergoing phase transitions, which cannot be treated with, e.g., linear response theory. The present work includes time-dependent stochastic perturbations in the theory using the Karhunen-Loève theorem. This leads to three different investigations of a given process. In the first, a single realization of the stochastic coefficients is fixed, and averages are taken only over the initial conditions, as in a deterministic process. In the second, the initial condition is fixed, and averages are taken with respect to the distribution of stochastic coefficients. In the last investigation, one averages over both initial conditions and stochastic coefficients. We conclude by illustrating the applicability of the resulting exact response theory with simple examples.

Surrealism holds that observables behave as if T were true, whereas scientific realism holds that T is true. Surrealism and scientific realism give different explanations of why T is empirically adequate. According to surrealism, T is empirically adequate because observables behave as if it were true. According to scientific realism, T is empirically adequate because it is true. I argue that the surrealist explanation merely clarifies the concept of empirical adequacy, whereas the realist explanation makes an inductive inference about T. Therefore, the surrealist explanation is a conceptual one, whereas the realist explanation is an empirical one, and the former is not an alternative to the latter. [ABSTRACT FROM AUTHOR]

The kinematical foundations of Schwinger's algebra of selective measurements were discussed in [F. M. Ciaglia, A. Ibort and G. Marmo, Schwinger's picture of quantum mechanics I: Groupoids, To appear in IJGMMP (2019)] and, as a consequence of this, a new picture of quantum mechanics based on groupoids was proposed. In this paper, the dynamical aspects of the theory are analyzed. For that, the algebra generated by the observables, as well as the notion of state, are discussed, and the structure of the transition functions, that plays an instrumental role in Schwinger's picture, is elucidated. A Hamiltonian picture of dynamical evolution emerges naturally, and the formalism offers a simple way to discuss the quantum-to-classical transition. Some basic examples, the qubit and the harmonic oscillator, are examined, and the relation with the standard Dirac–Schrödinger and Born–Jordan–Heisenberg pictures is discussed. [ABSTRACT FROM AUTHOR]