This is a list of this week’s papers on quantum foundations published in the various journals or uploaded to the preprint servers such as arxiv.org and PhilSci Archive.
Latest Results for Foundations of Physics
on 2015-6-06 12:00am GMT
Abstract
We construct a world model consisting of a matter field living in 4 dimensional spacetime and a gravitational field living in 11 dimensional spacetime. The seven hidden dimensions are compactified within a radius estimated by reproducing the particle–wave characteristics of diffraction experiments. In the presence of matter fields the gravitational field develops localized modes with elementary excitations called gravonons which are induced by the sources (massive particles). The final world model treated here contains only gravonons and a scalar matter field. The gravonons are localized in the environment of the massive particles which generate them. The solution of the Schrödinger equation for the world model yields matter fields which are localized in the 4 dimensional subspace. The localization has the following properties: (i) There is a chooser mechanism for the selection of the localization site. (ii) The chooser selects one site on the basis of minor energy differences and differences in the gravonon structure between the sites, which at present cannot be controlled experimentally and therefore let the choice appear statistical. (iii) The changes from one localization site to a neighbouring one take place in a telegraph-signal like manner. (iv) The times at which telegraph like jumps occur depend on subtleties of the gravonon structure which at present cannot be controlled experimentally and therefore let the telegraph-like jumps appear statistical. (v) The fact that the dynamical law acts in the configuration space of fields living in 11 dimensional spacetime lets the events observed in 4 dimensional spacetime appear non-local. In this way the phenomenology of CQM is obtained without the need of introducing the process of collapse and a probabilistic interpretation of the wave function. Operators defining observables need not be introduced. All experimental findings are explained in a deterministic way as a consequence of the time development of the wave function in configuration space according to Schrödinger’s equation without the need of introducing a probabilistic interpretation.adult water slides for sale
Cosmological matter-antimatter asymmetry as a quantum fluctuation. (arXiv:1506.01511v1 [hep-ph])
on 2015-6-05 1:44am GMT
Authors: Archil Kobakhidze, Adrian Manning
We entertain a new paradigm according to which the observed matter-antimatter asymmetry is generated as a large-scale quantum fluctuation over the baryon-symmetric state that occurred during the cosmic inflation.
Exploring the limits of quantum nonlocality with entangled photons. (arXiv:1506.01649v1 [quant-ph])
on 2015-6-05 1:44am GMT
Authors: Bradley G. Christensen, Yeong-Cherng Liang, Nicolas Brunner, Nicolas Gisin, Paul G. Kwiat
Quantum nonlocality is arguably among the most counter-intuitive phenomena predicted by quantum theory. In recent years, the development of an abstract theory of nonlocality has brought a much deeper understanding of the subject. In parallel, experimental progress allowed for the demonstration of quantum nonlocality in a wide range of physical systems, and brings us close to a final loophole-free Bell test. Here we combine these theoretical and experimental developments in order to explore the limits of quantum nonlocality. This approach represents a thorough test of quantum theory, and could provide evidence of new physics beyond the quantum model. Using a versatile and high-fidelity source of pairs of polarization entangled photons, we explore the boundary of quantum correlations, present the most nonlocal correlations ever reported, and demonstrate the phenomenon of more nonlocality with less entanglement. Our results are in remarkable agreement with quantum predictions.
Bounding Quantum Contextuality with Lack of Third-Order Interference
PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
on 2015-6-04 2:00pm GMT
Author(s): Joe Henson
Recently, many simple principles have been proposed that can explain quantum limitations on possible sets of experimental probabilities in nonlocality and contextuality experiments. However, few implications between these principles are known. Here it is shown that the lack of irreducible third-orde…
[Phys. Rev. Lett. 114, 220403] Published Thu Jun 04, 2015
Simple Explanation of the Quantum Limits of Genuine n-Body Nonlocality
PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
on 2015-6-04 2:00pm GMT
Author(s): Adán Cabello
Quantum n-body correlations cannot be explained with (n−1)-body nonlocality. However, this genuine n-body nonlocality cannot surpass certain bounds. Here we address the problem of identifying the principles responsible for these bounds. We show that, for any n≥2, the exclusivity principle, as derive…
[Phys. Rev. Lett. 114, 220402] Published Thu Jun 04, 2015
Necessary and sufficient conditions for macroscopic realism from quantum mechanics
on 2015-6-04 2:00pm GMT
Author(s): Lucas Clemente and Johannes Kofler
Macroscopic realism, the classical world view that macroscopic objects exist independently of and are not influenced by measurements, is usually tested using Leggett-Garg inequalities. Recently, another necessary condition called no-signaling in time (NSIT) has been proposed as a witness for nonclas…
[Phys. Rev. A 91, 062103] Published Thu Jun 04, 2015
Demonstration of Quantum Nonlocality in the Presence of Measurement Dependence
PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
on 2015-6-04 2:00pm GMT
Author(s): Djeylan Aktas, Sébastien Tanzilli, Anthony Martin, Gilles Pütz, Rob Thew, and Nicolas Gisin
Quantum nonlocality stands as a resource for device independent quantum information processing (DIQIP), such as, for instance, device independent quantum key distribution. We investigate, experimentally, the assumption of limited measurement dependence, i.e., that the measurement settings used in Be…
[Phys. Rev. Lett. 114, 220404] Published Thu Jun 04, 2015
Locality of Gravitational Systems from Entanglement of Conformal Field Theories
on 2015-6-02 2:00pm GMT
Author(s): Jennifer Lin, Matilde Marcolli, Hirosi Ooguri, and Bogdan Stoica
AdS/CFT correspondence has uncovered a relationship between the quantum entanglement of non-gravitating systems and the equations of general relativity in the presence of matter sources.
[Phys. Rev. Lett. 114, 221601] Published Tue Jun 02, 2015
on 2015-6-02 9:06am GMT
Authors: Marek Czachor
Arithmetic operations can be defined in various ways, even if one assumes commutativity and associativity of addition and multiplication, and distributivity of multiplication with respect to addition. In consequence, whenever one encounters `plus’ or `times’ one has certain freedom of interpreting this operation. This leads to some freedom in definitions of derivatives, integrals and, thus, practically all equations occurring in natural sciences. A change of realization of arithmetics, without altering the remaining structures of a given equation, plays the same role as a symmetry transformation. An appropriate construction of arithmetics turns out to be particularly important for dynamical systems in fractal space-times. Simple examples from classical and quantum, relativistic and nonrelativistic physics are discussed.
A Note on Black Hole Entropy in Loop Quantum Gravity. (arXiv:1410.5763v4 [gr-qc] UPDATED)
on 2015-6-02 9:06am GMT
Authors: S. Carlip
Several recent results have hinted that black hole thermodynamics in loop quantum gravity simplifies if one chooses an imaginary Barbero-Immirzi parameter $\gamma=i$. This suggests a connection with $\mathrm{SL}(2,\mathbb{C})$ or $\mathrm{SL}(2,\mathbb{R})$ conformal field theories at the “boundaries” formed by spin network edges intersecting the horizon. I present a bit of background regarding the relevant conformal field theories, along with some speculations about how they might be used to count black hole states. I show, in particular, that a set of unproven but plausible assumptions can lead to a boundary conformal field theory whose density of states matches the Bekenstein-Hawking entropy.
Crystallization of space: Space-time fractals from fractal arithmetics. (arXiv:1506.00487v1 [gr-qc])
on 2015-6-02 9:06am GMT
Authors: Diederik Aerts, Marek Czachor, Maciej Kuna
Fractals such as the Cantor set can be equipped with intrinsic arithmetic operations (addition, subtraction, multiplication, division) that map the fractal into itself. The arithmetics allows one to define calculus and algebra intrinsic to the fractal in question, and one can formulate classical and quantum physics within the fractal set. In particular, fractals in space-time can be generated by means of homogeneous spaces associated with appropriate Lie groups. The construction is illustrated by explicit examples.
on 2015-6-02 9:06am GMT
Authors: Stefan Teufel, Roderich Tumulka
We propose a novel type of Hamiltonians for quantum field theories. They are mathematically well-defined (and in particular, ultraviolet finite) without any ultraviolet cut-off such as smearing out the particles over a nonzero radius; rather, the particles are assigned radius zero. We describe explicit examples of such Hamiltonians. Their definition, which is best expressed in the particle-position representation of the wave function, involves a novel type of boundary condition on the wave function, which we call an interior-boundary condition. The relevant configuration space is one of a variable number of particles, and the relevant boundary consists of the configurations with two or more particles at the same location. The interior-boundary condition relates the value (or derivative) of the wave function at a boundary point to the value of the wave function at an interior point (here, in a sector of configuration space corresponding to a lesser number of particles).
Quantum from principles. (arXiv:1506.00398v1 [quant-ph])
on 2015-6-02 9:06am GMT
Authors: Giulio Chiribella, Giacomo Mauro D’Ariano, Paolo Perinotti
Quantum theory was discovered in an adventurous way, under the urge to solve puzzles-like the spectrum of the blackbody radiation-that haunted the physics community at the beginning of the 20th century. It soon became clear, though, that quantum theory was not just a theory of specific physical systems, but rather a new language of universal applicability. Can this language be reconstructed from first principles? Can we arrive at it from logical reasoning, instead of ad hoc guesswork? A positive answer was provided in Refs. [1, 2], where we put forward six principles that identify quantum theory uniquely in a broad class of theories. We first defined a class of “theories of information”, constructed as extensions of probability theory in which events can be connected into networks. In this framework, we formulated the six principles as rules governing the control and the accessibility of information. Directly from these rules, we reconstructed a number of quantum information features, and eventually, the whole Hilbert space framework. In short, our principles characterize quantum theory as the theory of information that allows for maximal control of randomness.
on 2015-6-02 9:06am GMT
Authors: Kim Joris Boström
A non-relativistic quantum mechanical theory is proposed that describes the universe as a continuum of worlds whose mutual interference gives rise to quantum phenomena. A logical framework is introduced to properly deal with propositions about objects in a multiplicity of worlds. In this logical framework, the continuum of worlds is treated similarly to the continuum of time points; both “time” and “world” are considered as mutually independent modes of existence. The theory combines elements of Bohmian mechanics and of Everett’s many-worlds interpretation; it has a clear ontology and a set of precisely defined postulates from where the predictions of standard quantum mechanics can be derived. Probability as given by the Born rule emerges as a consequence of insufficient knowledge of observers about which world it is that they live in. The theory describes a continuum of worlds rather than a single world or a discrete set of worlds, so it is similar in spirit to many-worlds interpretations based on Everett’s approach, without being actually reducible to these. In particular, there is no splitting of worlds, which is a typical feature of Everett-type theories. Altogether, the theory explains 1) the subjective occurrence of probabilities, 2) their quantitative value as given by the Born rule, and 3) the apparently random “collapse of the wavefunction” caused by the measurement, while still being an objectively deterministic theory.
Short-Time Propagators and the Born–Jordan Quantization Rule. (arXiv:1506.00111v1 [quant-ph])
on 2015-6-02 9:06am GMT
Authors: Maurice A. de Gosson
In the present paper we give a physical motivation for Born–Jordan quantization for arbitrary observables; it corrects previous unsuccessful attempts involving path integral arguments, and justifies earlier work by Garrod and Kerner and Sutcliffe, which was rebuked by Cohen. For this purpose we use correct short-time approximations to the solutions of Schr\”odinger’s equation, extending previous constructions of Makri and Miller, and the present author. Our constructions make clear that the formula proposed (but not justified) by Kerner and Sutcliffe coincides with the modern pseudo-differential form of Born and Jordan operators, as used in quantum mechanics and time-frequency analysis.
Comments On: A Universe From Nothing. (arXiv:1405.6091v4 [physics.gen-ph] UPDATED)
physics.hist-ph updates on arXiv.org
on 2015-6-02 9:06am GMT
Authors: Ikjyot Singh Kohli
We study some claims in Krauss’ recent book, \emph{A Universe from Nothing: Why there is something rather than nothing}, that are employed to show that a universe can come from “nothing”. In this brief paper, we show that many of the claims are not supported in full by modern general relativity theory or quantum field theory in curved spacetime.
Latest Results for Foundations of Physics
on 2015-6-02 12:00am GMT
Abstract
In a recent paper the authors studied numerically the hydrogen ground state in stochastic electrodynamics (SED) within the the non-relativistic approximation. In quantum theory the leading non-relativistic corrections to the ground state energy dominate the Lamb shift related to the photon cloud that should cause the quantum-like behaviour of SED. The present work takes these corrections into account in the numerical modelling. It is found that they have little effect; the self-ionisation that occurs without them remains present. It is speculated that the point-charge approximation for the electron is the cause of the failure.
Lagrangian Description for Particle Interpretations of Quantum Mechanics: Single-Particle Case
Latest Results for Foundations of Physics
on 2015-6-02 12:00am GMT
Abstract
A Lagrangian description is presented which can be used in conjunction with particle interpretations of quantum mechanics. A special example of such an interpretation is the well-known Bohm model. The Lagrangian density introduced here also contains a potential for guiding the particle. The advantages of this description are that the field equations and the particle equations of motion can both be deduced from a single Lagrangian density expression and that conservation of energy and momentum are assured. After being developed in a general form, this Lagrangian formulation is then applied to the special case of the Bohm model as an example. It is thereby demonstrated that such a Lagrangian description is compatible with the predictions of quantum mechanics.
Classical and Quantum Gravity – latest papers
on 2015-6-01 12:00am GMT
We give a brief review of the AdS/CFT correspondence, which posits the equivalence between a certain gravitational theory and a lower-dimensional non-gravitational one. This remarkable duality, formulated in 1997, has sparked a vigorous research program that has gained in breadth over the years, with applications to many aspects of theoretical (and even experimental) physics, not least to general relativity and quantum gravity. To put the AdS/CFT correspondence into historical context, we start by reviewing the relevant aspects of string theory (of which no prior knowledge is assumed). We then develop the statement of the correspondence, and explain how the two sides of the duality map into each other. Finally, we discuss the implications and applications of the correspondence, and indicate some of the current trends in this subject. The presentation attempts to convey the main concepts in a simple and self-contained manner, relegating supplementary remarks to footnotes.
The ADM papers and part of their modern legacy: loop quantum gravity
Classical and Quantum Gravity – latest papers
on 2015-6-01 12:00am GMT
We present a summary for non-specialists of loop quantum gravity as part of the modern legacy of the series of papers by Arnowitt, Deser and Misner circa 1960.
The strange equation of quantum gravity
Classical and Quantum Gravity – latest papers
on 2015-6-01 12:00am GMT
Disavowed by one of its fathers, ill-defined, never empirically tested, the Wheeler–DeWitt equation has nevertheless had a powerful influence on fundamental physics. A well-deserved one.
