# Weekly Papers on Quantum Foundations (21)

This is a list of this week’s papers on quantum foundations published in various journals or uploaded to preprint servers such as arxiv.org and PhilSci Archive.

Running vacuum in the Universe and the time variation of the fundamental constants of Nature. (arXiv:1605.06104v1 [hep-ph])

on 2016-5-21 8:37am GMT

Authors: Harald FritzschRafael C. NunesJoan Sola

We compute the time variation of the fundamental constants (such as the ratio of the proton mass to the electron mass, the strong coupling constant, the fine structure constant and Newton’s constant) within the context of the so-called running vacuum models (RVM’s) of the cosmic evolution. Recently, compelling evidence has been provided showing that these models are able to fit the main cosmological data (SNIa+BAO+H(z)+LSS+BBN+CMB) significantly better than the concordance $\Lambda$CDM model. Specifically, the vacuum parameters of the RVM (i.e. those responsible for the dynamics of the vacuum energy) prove to be nonzero at a confidence level of $\gtrsim3\sigma$. Here we use such remarkable status of the RVM’s to make definite predictions on the cosmic time variation of the fundamental constants. It turns out that the predicted variations are close to the present observational limits. Furthermore, we find that the time variation of the dark matter particles should be necessarily involved in the total mass variation of our Universe. A positive measurement of this kind of effects could be interpreted as strong support to the “micro and macro connection” (viz. the dynamical feedback between the evolution of the cosmological parameters and the time variation of the fundamental constants of the microscopic world), previously proposed by two of us (HF and JS).

Quantum nonlocality, and the end of classical space-time. (arXiv:1605.06022v1 [gr-qc])

on 2016-5-21 8:37am GMT

Authors: Shreya BanerjeeSayantani BeraT. P. Singh

Quantum non-local correlations and the acausal, spooky action at a distance suggest a discord between quantum theory and special relativity. We propose a resolution for this discord by first observing that there is a problem of time in quantum theory. There should exist a reformulation of quantum theory which does not refer to classical time. Such a reformulation is obtained by suggesting that space-time is fundamentally non-commutative. Quantum theory without classical time is the equilibrium statistical thermodynamics of the underlying non-commutative relativity. Stochastic fluctuations about equilibrium give rise to the classical limit and ordinary space-time geometry. However, measurement on an entangled state can be correctly described only in the underlying non-commutative space-time, where there is no causality violation, nor a spooky action at a distance.

Observational strong gravity and quantum black hole structure. (arXiv:1605.05341v1 [gr-qc] CROSS LISTED)

on 2016-5-21 8:37am GMT

Authors: Steven B. Giddings

Quantum considerations have led many theorists to believe that classical black hole physics is modified not just deep inside black holes but at horizon scales, or even further outward. The near-horizon regime has just begun to be observationally probed for astrophysical black holes — both by LIGO, and by the Event Horizon Telescope. This suggests exciting prospects for observational constraints on or discovery of new quantum black hole structure.

Emergent dark energy via decoherence in quantum interactions. (arXiv:1605.05980v1 [gr-qc])

on 2016-5-21 8:37am GMT

Much effort has been devoted into understanding the quantum mechanical properties of gravitational interactions. Here we explore the recent suggestion that gravitational interactions are a fundamental classical channel that is described by continuous quantum measurements and feedforward (CQMF). Specifically, we investigate the possibility that some properties of our universe, modeled using a Friedman-Robertson-Walker metric, can emerge from CQMF by introducing an underlying quantum system for the dynamical variables, avoiding well known difficulties in trying to quantize the spacetime itself. We show that the quantum decoherence necessary in such a measurement model manifests itself as a dark energy fluid that fills the spacetime and whose equation of state asymptotically oscillates around the value $w=-1/3$, regardless of the spatial curvature, which provides the bound between accelerating and decelerating expanding FRW cosmologies.

Quantum epistemology from subquantum ontology: quantum mechanics from theory of classical random fields. (arXiv:1605.05907v1 [quant-ph])

on 2016-5-21 8:37am GMT

Authors: Andrei Khrennikov

The scientific methodology based on two descriptive levels, ontic (reality as it is ) and epistemic (observational), is briefly presented. Following Schr\”odinger, we point to the possible gap between these two descriptions. Our main aim is to show that, although ontic entities may be inaccessible for observations, they can be useful for clarification of the physical nature of operational epistemic entities. We illustrate this thesis by the concrete example: starting with the concrete ontic model preceding quantum mechanics (the latter is treated as an epistemic model), namely, prequantum classical statistical field theory (PCSFT), we propose the natural physical interpretation for the basic quantum mechanical entity – the quantum state (“wave function”). The correspondence PCSFT to QM is not straightforward, it couples the covariance operators of classical (prequantum) random fields with the quantum density operators. We use this correspondence to clarify the physical meaning of the pure quantum state and the superposition principle – by using the formalism of classical field correlations.

A note on superposition of two unknown states using Deutsch CTC model. (arXiv:1605.06005v1 [quant-ph])

on 2016-5-21 8:36am GMT

Authors: Sasha SamiIndranil Chakrabarty

In a recent work, authors prove a yet another no-go theorem that forbids the existence of a universal probabilistic quantum protocol producing a superposition of two unknown quantum states. In this short note, we show that in the presence of closed time like curves, one can indeed create superposition of unknown quantum states and evade the no-go result.

Quantum State Reduction by Matter-Phase-Related Measurements in Optical Lattices. (arXiv:1605.06000v1 [quant-ph])

on 2016-5-21 8:36am GMT

A many-body atomic system coupled to quantized light is subject to weak measurement. Instead of coupling light to the on-site density, we consider the quantum backaction due to the measurement of matter-phase-related variables such as global phase coherence. We show how this unconventional approach opens up new opportunities to affect system evolution and demonstrate how this can lead to a new class of measurement projections, thus extending the measurement postulate for the case of strong competition with the system’s own evolution.

Quantum Horn’s lemma, finite heat baths, and the third law of thermodynamics. (arXiv:1605.06092v1 [quant-ph])

on 2016-5-21 8:36am GMT

Authors: Jakob ScharlauMarkus P. Mueller

Interactions of quantum systems with their environment play a crucial role in resource-theoretic approaches to thermodynamics in the microscopic regime. Here, we analyze the possible state transitions in the presence of “small” heat baths of bounded dimension and energy. We show that for operations on quantum systems with fully degenerate Hamiltonian (noisy operations), all possible state transitions can be realized exactly with a bath that is of the same size as the system or smaller, which proves a quantum version of Horn’s lemma as conjectured by Bengtsson and Zyczkowski. On the other hand, if the system’s Hamiltonian is not fully degenerate (thermal operations), we show that some possible transitions can only be performed with a heat bath that is unbounded in size and energy, which is an instance of the third law of thermodynamics. In both cases, we prove that quantum operations yield an advantage over classical ones for any given finite heat bath, by allowing a larger and more physically realistic set of state transitions.

Quantum enhanced feedback cooling of a mechanical oscillator. (arXiv:1605.05949v1 [quant-ph])

on 2016-5-21 8:36am GMT

Laser cooling is a fundamental technique used in primary atomic frequency standards, quantum computers, quantum condensed matter physics and tests of fundamental physics, among other areas. It has been known since the early 1990s that laser cooling can, in principle, be improved by using squeezed light as an electromagnetic reservoir; while quantum feedback control using a squeezed light probe is also predicted to allow improved cooling. Here, we implement quantum feedback control of a micro-mechanical oscillator for the first time with a squeezed probe field. This allows quantum-enhanced feedback cooling with a measurement rate greater than it is possible with classical light, and a consequent reduction in the final oscillator temperature. Our results have significance for future applications in areas ranging from quantum information networks, to quantum-enhanced force and displacement measurements and fundamental tests of macroscopic quantum mechanics.

Macroscopic quantum measurements: In what direction does a magnet point?. (arXiv:1605.05956v1 [quant-ph])

on 2016-5-21 8:36am GMT

We introduce the concept of macroscopic quantum measurement, that is, a quantum formalism describing the measurements we perform continuously in our everyday life; for example, when looking at a magnet. We idealize the problem by considering parallel spins whose direction has to be estimated. We present a physical measurement model weak enough to almost not disturb the quantum state, but strong enough to provide almost the maximal amount of information in a single shot. Interestingly an intermediate coupling strength between spin system and measurement apparatus achieves better results than a strong coupling.

[Book Review] Philosophy for physicists

Science: Current Issue

on 2016-5-20 12:00am GMT

The 20th-century philosopher Wilfrid Sellars characterized the aim of philosophy as “to understand how things in the broadest possible sense of the term hang together in the broadest possible sense of the term.” This is also physicist Sean Carroll’s aim in his new book, The Big Picture. He sets out to show how various phenomena, including thought, choice, conscioussness, and value, hang together with the scientific account of reality that has been developed in physics in the past 100 years. He attempts to do all this without relying on specialized jargon from philosophy and physics, and succeeds spectacularly in achieving both aims. Author: Barry Loewer

What is theoretical progress of science?

Latest Results for Synthese

on 2016-5-19 12:00am GMT

Abstract

The epistemic conception of scientific progress equates progress with accumulation of scientific knowledge. I argue that the epistemic conception fails to fully capture scientific progress: theoretical progress, in particular, can transcend scientific knowledge in important ways. Sometimes theoretical progress can be a matter of new theories ‘latching better onto unobservable reality’ in a way that need not be a matter of new knowledge. Recognising this further dimension of theoretical progress is particularly significant for understanding scientific realism, since realism is naturally construed as the claim that science makes theoretical progress. Some prominent realist positions (regarding fundamental physics, in particular) are best understood in terms of commitment to theoretical progress that cannot be equated with accumulation of scientific knowledge.

Axion Experiments to Algebraic Geometry: Testing Quantum Gravity via the Weak Gravity Conjecture. (arXiv:1605.05311v1 [hep-th])

on 2016-5-18 1:40am GMT

Authors: Ben HeidenreichMatthew ReeceTom Rudelius

Common features of known quantum gravity theories may hint at the general nature of quantum gravity. The absence of continuous global symmetries is one such feature. This inspired the Weak Gravity Conjecture, which bounds masses of charged particles. We propose the Lattice Weak Gravity Conjecture, which further requires the existence of an infinite tower of particles of all possible charges under both abelian and nonabelian gauge groups and directly implies a cutoff for quantum field theory. It holds in a wide variety of string theory examples and has testable consequences for the real world and for pure mathematics. We sketch some implications of these ideas for models of inflation, for the QCD axion (and LIGO), for conformal field theory, and for algebraic geometry.

Reconstructing spacetime from the hologram, even in the classical limit, requires physics beyond the Planck scale. (arXiv:1605.05288v1 [hep-th])

on 2016-5-18 1:40am GMT

Authors: David BerensteinAlexandra Miller

We argue in this essay that for classical configurations of gravity in the AdS/CFT setup, it is in general impossible to reconstruct the bulk geometry from the leading asymptotic behavior of the classical fields in gravity alone. This is possible sufficiently near the vacuum, but not more generally. We argue this by using a counter-example that utilizes the supersymmetric geometries constructed by Lin, Lunin, and Maldacena. In the dual quantum field theory, the additional data required to complete the geometry is encoded in modes that near the vacuum geometry lie beyond the Planck scale.

Realistic Observable in Background-Free Quantum Gravity: the Planck-Star Tunnelling-Time. (arXiv:1605.05268v1 [gr-qc])

on 2016-5-18 1:40am GMT

A gravitationally collapsed object can bounce-out from its horizon via a tunnelling process that violates the classical equations in a finite region. Since tunnelling is a non-perturbative phenomenon, it cannot be described in terms of quantum fluctuations around a classical solution and a background-free formulation of quantum gravity is needed to analyze it. Here we use Loop Quantum Gravity to compute the amplitude for this process, in a first approximation. The amplitude determines the tunnelling time as a function of the mass. This is the key information to evaluate the astrophysical relevance of this process. The calculation offers a template and a concrete example of how a background-free quantum theory of gravity can be used to compute a realistical observable quantity.

The Quantum Black Hole as a Hydrogen Atom: Microstates Without Strings Attached. (arXiv:1605.05119v1 [gr-qc])

on 2016-5-18 1:40am GMT

Authors: Gerard t Hooft

Applying an expansion in spherical harmonics, turns the black hole with its microstates into something about as transparent as the hydrogen atom was in the early days of quantum mechanics. It enables us to present a concise description of the evolution laws of these microstates, linking them to perturbative quantum field theory, in the background of the Schwarzschild metric. Three pieces of insight are obtained: One, we learn how the gravitational back reaction, whose dominant component can be calculated exactly, turns particles entering the hole, into particles leaving it, by exchanging the momentum- and position operators; two, we find out how this effect removes firewalls, both on the future and the past event horizon, and three, we discover that the presence of region II in the Penrose diagram forces a topological twist in the background metric, culminating in antipodal identification. Although a cut-off is required that effectively replaces the transverse coordinates by a lattice, the effect of such a cut-off minimizes when the spherical wave expansion is applied. This expansion then reveals exactly how antipodal identification restores unitarity – for each partial wave separately. We expect that these ideas will provide new insights in some highly non-trivial topological space-time features at the Planck scale.

An informationally-complete unification of quantum spacetime and matter. (arXiv:1412.3662v4 [gr-qc] CROSS LISTED)

on 2016-5-18 1:40am GMT

Authors: Zeng-Bing Chen

It was known long ago that quantum theory and general relativity, two pillars of modern physics, are in sharp conflict in their foundations. Their fundamental inconsistencies render a consistent theory of quantum gravity the most challenging problem in physics. Here we propose an informationally-complete quantum field theory (ICQFT), which describes elementary particles, their gauge fields and gravity as a trinity without the Hilbert-space inconsistency of Einstein’s equation. We then argue that the ICQFT provides a coherent picture and conceptual framework of unifying matter and spacetime (gravity) and gives a compelling solution to the problem of time and time’s arrow. The trinary field is characterized by dual entanglement and dual dynamics. Spacetime-matter entanglement allows us to give a correct classical limit (i.e., classical Einstein equation) and a natural explanation of the holographic principle. We predict the interior quantum state of a Schwarzschild black hole and, based on the state, conjecture a possible candidate to dark matter/energy.

Quantum Mechanical Inclusion of the Source in the Aharonov-Bohm Effects. (arXiv:1507.00068v2 [quant-ph] UPDATED)

on 2016-5-18 1:40am GMT

Authors: Philip PearleAnthony Rizzi

We consider charged particles with well-localized positions and momenta moving in arbitrary potentials (due to the other particles) on pre-determined one-dimensional paths (e.g, within frictionless tubes of predetermined shape). Using suitable approximations, we calculate the phase associated to each particle in the system. We show, in an interference experiment involving many such particles,that the phase shift is given by the sum for each particle of Aharonov-Bohm (A-B)-type integrals over vector and scalar potentials. We then apply our expression to Vaidman’s recent demonstration, by a semi-classical calculation, that the particles in the solenoid moving under the electric field of the electron generate the usual A-B phase shift. This is mathematically and conceptually different from the usual calculation, where the phase shift is due to the electron moving in the nonfield-producing vector potential of the solenoid. We verify Vaidman’s result using our completely quantum calculation, first by a general theorem, followed by a direct calculation. We take the point of view of Vaidman, that this is an alternative way to calculate the A-B phase shift (a position we bolster in a second paper). We also apply our expression to the electric A-B phase shift, emphasizing that a similar dichotomy exists here, of two different ways of calculating (and conceptualizing) the same thing. One way treats the electron as moving in the nonfield-producing scalar potential outside charged capacitor plates. The other way treats the plates as moving in the electric field of the electron. Thus, unlike what is often thought, we argue it is possible to view both the electric and magnetic A-B effects as arising from forces.

Irrelevance of Bell’s Theorem for experiments involving correlations in space and time: a specific loophole-free computer-example. (arXiv:1605.05237v1 [physics.gen-ph])

on 2016-5-18 1:40am GMT

Authors: Hans De RaedtKristel MichielsenKarl Hess

John Bell is generally credited to have accomplished the remarkable “proof” that any theory of physics, which is both Einstein-local and “realistic” (counterfactually definite), results in a strong upper bound to the correlations that are measured in space and time. He thus predicts that Einstein-Podolsky-Rosen experiments cannot violate Bell- type inequalities. We present a counterexample to this claim, based on discrete-event computer simulations. Our model-results fully agree with the predictions of quantum theory for Einstein-Podolsky-Rosen-Bohm experiments and are free of the detection- or a coincidence-loophole.

How the instant collapse of a spatially-extended quantum state is consistent with relativity of simultaneity. (arXiv:1605.05242v1 [physics.gen-ph])

on 2016-5-18 1:40am GMT

Authors: Moses Fayngold

A thought experiment is considered on observation of instantaneous collapse of an extended wave packet. According to relativity of simultaneity, such a collapse being instantaneous in some reference frame must be a lasting process in other frames. But according to quantum mechanics, collapse is instantaneous in any frame. Mathematical structure of quantum mechanics eliminates any contradictions between these two apparently conflicting statements. Here the invariance of quantum-mechanical collapse is shown to follow directly from the Born postulate, without any use of mathematical properties of quantum operators. The consistency of quantum mechanics with Relativity is also shown for instant disentanglement of a composite system.

New Insights into Quantum Gravity from Gauge/gravity Duality. (arXiv:1605.04335v1 [hep-th])

on 2016-5-17 12:16pm GMT

Authors: Netta EngelhardtGary T. Horowitz

Using gauge/gravity duality, we deduce several nontrivial consequences of quantum gravity from simple properties of the dual field theory. These include: (1) a version of cosmic censorship, (2) restrictions on evolution through black hole singularities, and (3) the exclusion of certain cosmological bounces. In the classical limit, the latter implies a new singularity theorem.

Do spikes persist in a quantum treatment of spacetime singularities?. (arXiv:1605.04648v1 [gr-qc])

on 2016-5-17 12:16pm GMT

The classical approach to spacetime singularities leads to a simplified dynamics in which spatial derivatives become unimportant compared to time derivatives, and thus each spatial point essentially becomes uncoupled from its neighbors. This uncoupled dynamics leads to sharp features (called “spikes”) as follows: particular spatial points follow an exceptional dynamical path that differs from that of their neighbors, with the consequence that in the neighborhood of these exceptional points the spatial profile becomes ever more sharp. Spikes are consequences of the BKL-type oscillatory evolution towards generic singularities of spacetime. Do spikes persist when the spacetime dynamics are treated using quantum mechanics? To address this question, we treat a Hamiltonian system that describes the dynamics of the approach to the singularity and consider how to quantize that system. We argue that this particular system is best treated using an affine quantization approach (rather than the more familiar methods of cannonical quantization) and we set up the formalism needed for this treatment.

Are Most Particles Gravitons?. (arXiv:1605.04351v1 [hep-th])

on 2016-5-17 12:16pm GMT

Authors: Don N. Page

The number of baryons in the observable universe is of the order of $10^{80}$, as is the number of electrons. The number of photons is about nine orders of magnitude greater, $10^{89}$, as is the estimated number of neutrinos. However, the number of gravitons could be more than twenty orders of magnitude larger yet, of the order of $10^{113} r$, where $r$ is the tensor-to-scalar ratio for quantum fluctuations produced by inflation, which could be as high as $0.1$.

Observable Effects of Quantum Gravity. (arXiv:1605.04361v1 [gr-qc])

on 2016-5-17 12:16pm GMT

We discuss the generic phenomenology of quantum gravity and, in particular, argue that the observable effects of quantum gravity, associated with new, extended, non-local, non-particle-like quanta, and accompanied by a dynamical energy-momentum space, are not necessarily Planckian and that they could be observed at much lower and experimentally accessible energy scales.

From Boole to Leggett-Garg: Epistemology of Bell-type Inequalities. (arXiv:1605.04887v1 [quant-ph])

on 2016-5-17 12:15pm GMT

Authors: Karl HessHans De RaedtKristel Michielsen

In 1862, George Boole derived an inequality for variables, now known as Boolean variables, that in his opinion represents a demarcation line between possible and impossible experience. This inequality forms an important milestone in the epistemology of probability theory and probability measures.

In 1985 Leggett and Garg derived a physics related inequality, mathematically identical to Boole’s, that according to them represents a demarcation between macroscopic realism and quantum mechanics. Their formalism, constructed for the magnetic flux of SQUIDS, includes general features and applies also to many other quantum experiments.

We show that a wide gulf, a wide divide, separates the “sense impressions” and corresponding data, as well as the postulates of macroscopic realism, from the mathematical abstractions that are used to derive the inequality of Leggett-Garg. If the gulf can be bridged, one may indeed derive the said inequality, which is then clearly a demarcation between possible and impossible experience: it cannot be violated and is not violated by quantum theory. We deduce from this fact that a violation of the Leggett-Garg inequality does not mean that the SQUID-flux is not there when nobody looks, as Leggett-Garg suggest, but instead that the probability measures may not be what Leggett-Garg have assumed them to be, when no data can be secured that directly relate to them. We show that similar considerations apply to other well known quantum interpretation-puzzles including that of the two-slit experiment.

On the Measurement in Quantum Mechanics: the Consistent Measurement Apparatus. (arXiv:1602.08818v2 [quant-ph] UPDATED)

on 2016-5-17 12:15pm GMT

Authors: Fabio L. TraversaGuillermo Albareda

Measurement in quantum mechanics is generally described as an irreversible process that perturbs the wavefunction describing a quantum system. In this work we establish a formal connection between the measurement description within the Copenhagen interpretation (i.e., through the collapse of the wavefunction) compared versus a picture in which the system and the measurement apparatus are considered as a whole. We first consider a projective measurement. In this limiting case, the natural requirements of consistency and equivalence between the two pictures lead to the rigorous definition of consistent measuring apparatus: the orthonormal wavefunctions from the Schmidt decomposition of the system plus apparatus must have non-overlapping supports. This result arises from the comparison of the two pictures (otherwise hidden), and while it seems to be an obvious conclusion in the limit of projective measurements, it has some nontrivial implications as one extends its validity to the domain of weak measurements. In this respect, we argue on the existence of two alternative approaches to mathematically constructing a weak measurement protocol. While the two approaches are equivalent from the system’s perspective, they do strongly differ from the apparatus point of view, and hence can be only distinguished one from each other in the picture where system and apparatus are considered as a whole. We show that only one of the two mathematical formulations of the weak measurement fulfills the consistent apparatus condition, while the combination of the two gives rise to a generalized weak measurements framework.

Infinite-dimensional Categorical Quantum Mechanics. (arXiv:1605.04305v1 [quant-ph])

on 2016-5-17 12:15pm GMT

Authors: Stefano GogiosoFabrizio Genovese

We use non-standard analysis to define a category $^\star\!\operatorname{Hilb}$ suitable for categorical quantum mechanics in arbitrary separable Hilbert spaces, and we show that standard bounded operators can be suitably embedded in it. We show the existence of unital special commutative $\dagger$-Frobenius algebras, and we conclude $^\star\!\operatorname{Hilb}$ to be compact closed, with partial traces and a Hilbert-Schmidt inner product on morphisms. We exemplify our techniques on the textbook case of 1-dimensional wavefunctions with periodic boundary conditions: we show the momentum and position observables to be well defined, and to give rise to a strongly complementary pair of unital commutative $\dagger$-Frobenius algebras.

Counterfactual Definiteness and Bell’s Inequality. (arXiv:1605.04889v1 [quant-ph])

on 2016-5-17 12:15pm GMT

Authors: Karl HessHans De RaedtKristel Michielsen

Counterfactual definiteness must be used as at least one of the postulates or axioms that are necessary to derive Bell-type inequalities. It is considered by many to be a postulate that is not only commensurate with classical physics (as for example Einstein’s special relativity), but also separates and distinguishes classical physics from quantum mechanics. It is the purpose of this paper to show that Bell’s choice of mathematical functions and independent variables implicitly includes counterfactual definiteness and reduces the generality of the physics of Bell-type theories so significantly that no meaningful comparison of these theories with actual Einstein-Podolsky-Rosen experiments can be made.

Does Bohm’s Quantum Force Have a Classical Origin?. (arXiv:1409.8271v12 [physics.class-ph] UPDATED)

on 2016-5-17 12:15pm GMT

Authors: David C. Lush

In the de Broglie – Bohm formulation of quantum mechanics, the electron is stationary in the ground state of hydrogenic atoms, because the quantum force exactly cancels the Coulomb attraction of the electron to the nucleus. In this paper it is shown that classical electrodynamics similarly predicts the Coulomb force can be effectively canceled by part of the magnetic force that occurs between two similar particles each consisting of a point charge moving with circulatory motion at the speed of light. Supposition of such motion is the basis of the {\em Zitterbewegung} interpretation of quantum mechanics. The magnetic force between two luminally-circulating charges for separation large compared to their circulatory motions contains a radial inverse square law part with magnitude equal to the Coulomb force, sinusoidally modulated by the phase difference between the circulatory motions. When the particles have equal mass and their circulatory motions are aligned but out of phase, part of the magnetic force is equal but opposite the Coulomb force. This raises a possibility that the quantum force of Bohmian mechanics may be attributable to the magnetic force of classical electrodynamics. It is further shown that non-relativistic relative motion between the particles leads to modulation of the magnetic force with spatial period equal to the de Broglie wavelength. Relativistic relative motion leads to modulation with spatial period equal to one-half the de Broglie wavelength. The factor of one-half is due to the zitterbewegung frequency of a spin-half particle being twice that of a spin-one particle of the same rest energy.

Quantizing the Vector Potential Reveals Alternative Views of the Magnetic Aharonov-Bohm Phase Shift. (arXiv:1605.04324v1 [quant-ph])

on 2016-5-17 12:15pm GMT

Authors: Philip PearleAnthony Rizzi

A complete quantum analysis of Aharonov-Bohm (A-B) magnetic phase shift involves three entities, the electron, the charges constituting the solenoid current, and the vector potential. The usual calculation supposes that the solenoid’s vector potential may be well-approximated as classical. The A-B shift is then acquired by the quantized electron moving in this vector potential. Recently, Vaidman presented a semi-classical calculation, later confirmed by a fully quantum calculation of Pearle and Rizzi, where it is supposed that the electron’s vector potential may be well-approximated as classical. The A-B shift is then acquired by the quantized solenoid charges moving in this vector potential. Here we present a third calculation, which supposes that the electron and solenoid currents may be well-approximated as classical sources. The A-B phase shift is then shown to be acquired by the quantized vector potential. We regard these as three equivalent alternative ways of calculating the A-B shift. To show this, consider the exact problem where all three entities are quantized. But, as in the first two cases above, make the supposition that it is a good approximation to take the vector potential as classical. With both the electron phase shift and the solenoid phase shift mechanisms operating, this gives twice the A-B phase shift. Thus, this is a faulty supposition. We make a better approximation. We take the wave function for the exact problem as the product of a vector potential wave function and an electron/solenoid wave function, and apply a variational principle. This leads to a Schr\”odinger equation for the electron/solenoid wave function with an additional term. The additional term can be written so as to cancel the electron phase shift mechanism, or to cancel the solenoid phase shift mechanism. This leads to three alternative views.

New assessment on the nonlocality of correlation boxes. (arXiv:1605.04577v1 [quant-ph])

on 2016-5-17 12:15pm GMT

Authors: A. P. CostaFernando Parisio

Correlation boxes are hypothetical systems capable of producing the maximal algebraic violation of Bell inequalities, beyond the quantum bound and without superluminal signaling. The fact that these systems show stronger correlations than those presented by maximally entangled quantum states has been regarded as a demonstration that the former are more nonlocal than the latter. By employing an alternative, consistent measure of nonlocality, we show that this conclusion is not necessarily true. In addition, we find a class of correlation boxes that are less nonlocal than the quantum singlet with respect to the Clauser-Horne-Shimony-Holt inequality, being, at the same time, more nonlocal with respect to the 3322 inequality.

Quantum Mechanics and Narratability

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

on 2016-5-15 10:06am GMT

Myrvold, Wayne C. (2016) Quantum Mechanics and Narratability. [Preprint]