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.

Quantum space-time of a charged black hole. (arXiv:1412.6055v1 [gr-qc])

on 2014-12-20 2:26am GMT

Authors: Rodolfo Gambini, Esteban Mato Capurro, Jorge Pullin

We quantize spherically symmetric electrovacuum gravity. The algebra of Hamiltonian constraints can be made Abelian via a rescaling and linear combination with the diffeomorphism constraint. As a result the constraint algebra is a true Lie algebra. We complete the Dirac quantization procedure using loop quantum gravity techniques. We present explicitly the exact solutions of the physical Hilbert space annihilated by all constraints. The resulting quantum space-times resolve the singularity present in the classical theory inside charged black holes and allows to extend the space-time through where the singularity used to be into new regions. We show that quantum discreteness of space-time may also play a role in stabilizing the Cauchy horizons, though back reaction calculations are needed to confirm this point.

Dualities. (arXiv:1412.5704v1 [hep-th])

on 2014-12-20 2:26am GMT

Authors: Joseph Polchinski

Duality, the equivalence between seemingly distinct quantum systems, is a curious property that has been known for at least three quarters of a century. In the past two decades it has played a central role in mapping out the structure of theoretical physics. I discuss the unexpected connections that have been revealed among quantum field theories and string theories.

Colloquium: Quantum root-mean-square error and measurement uncertainty relations

Recent Articles in Rev. Mod. Phys.

on 2014-12-18 3:00pm GMT

Author(s): Paul Busch, Pekka Lahti, and Reinhard F. Werner

Recent years have witnessed a controversy over Heisenberg’s famous error-disturbance relation. Here the conflict is resolved by way of an analysis of the possible conceptualizations of measurement error and disturbance in quantum mechanics. Two approaches to adapting the classic notion of root-mean-...

[Rev. Mod. Phys. 86, 1261] Published Thu Dec 18, 2014

Bloch-sphere colorings and Bell inequalities

on 2014-12-18 3:00pm GMT

Author(s): Adrian Kent and Damián Pitalúa-García

We consider the quantum and local hidden variable (LHV) correlations obtained by measuring a pair of qubits by projections defined by randomly chosen axes separated by an angle θ. Local hidden variables predict binary colorings of the Bloch sphere with antipodal points oppositely colored. We prove B...

[Phys. Rev. A 90, 062124] Published Thu Dec 18, 2014

on 2014-12-18 12:21pm GMT

Authors: Wojciech H. Zurek

Tracing flows of information in our quantum Universe explains why we see the world as classical.

Bohm's Quantum Potential as an Internal Energy. (arXiv:1412.5133v1 [quant-ph])

on 2014-12-17 7:44am GMT

Authors: Glen Dennis, Maurice de Gosson, Basil Hiley

We pursue our discussion of Fermi's surface initiated in Dennis, de Gosson and Hiley and show that Bohm's quantum potential can be viewed as an internal energy of a quantum system. This gives further insight into the role it played by the quantum potential in stationary states. It also allows us to provide a physically motivated derivation of Schr\"odinger's equation for a particle in an external potential.

on 2014-12-17 7:43am GMT

Authors: Diego Blas, Eugene Lim

Theories of gravitation without Lorentz invariance are candidates of low-energy descriptions of quantum gravity. In this review we will describe the phenomenological consequences of the candidates associated to the existence of a preferred time direction

QFT on curved spacetimes: axiomatic framework and examples. (arXiv:1412.5125v1 [math-ph])

on 2014-12-17 7:43am GMT

Authors: Klaus Fredenhagen, Katarzyna Rejzner

In this review article we want to expose a systematic development of quantum field theory on curved spacetimes. The leading principle is the emphasis on local properties. It turns out that this requires a reformulation of the QFT framework which also yields a new perspective for the theories on Minkowski space. The aim of the present work is to provide an almost self contained introduction into the framework, which should be accessible for both physicists and mathematicians.

on 2014-12-16 12:31pm GMT

Authors: Christopher A. Fuchs, Ruediger Schack

In QBism (or Quantum Bayesianism) a quantum state does not represent an element of physical reality but an agent's personal probability assignments, reflecting his subjective degrees of belief about the future content of his experience. In this paper, we contrast QBism with hidden-variable accounts of quantum mechanics and show the sense in which QBism explains quantum correlations. QBism's agent-centered worldview can be seen as a development of ideas expressed in Schr\"odinger's essay "Nature and the Greeks".

Quantum Measurement and the Paulian Idea. (arXiv:1412.4209v1 [quant-ph])

on 2014-12-16 12:31pm GMT

Authors: Christopher Fuchs, Ruediger Schack

In the quantum Bayesian (or QBist) conception of quantum theory, "quantum measurement" is understood not as a comparison of something pre-existent with a standard, but instead indicative of the creation of something new in the universe: Namely, the fresh experience any agent receives upon taking an action on the world. We explore the implications of this for any would-be ontology underlying QBism. The concept that presently stands out as a candidate "material for our universe's composition" is "experience" itself, or what John Wheeler called "observer-participancy".

on 2014-12-16 12:30pm GMT

Authors: Francisco S. N. Lobo, Gonzalo J. Olmo, D. Rubiera-Garcia

We argue that a microscopic structure for space-time such as that expected in a quantum foam scenario, in which microscopic wormholes and other topological structures should play a relevant role, might lead to an effective metric-affine geometry at larger scales. This idea is supported by the role that microscopic defects play in crystalline structures. With an explicit model we show that wormhole formation is possible in a metric-affine scenario, where the wormhole and the matter fields play a role analogous to that of defects in crystals. We also point out that in metric-affine geometries Einstein's equations with an effective cosmological constant appear as an attractor in the vacuum limit for a vast family of theories of gravity. This illustrates how lessons from solid state physics can be useful in unveiling the properties of the microcosmos and defining new avenues for modified theories of gravity.

On weak interactions as short-distance manifestations of gravity. (arXiv:1412.4513v1 [hep-ph])

on 2014-12-16 12:30pm GMT

Authors: Roberto Onofrio

We conjecture that weak interactions are peculiar manifestations of quantum gravity at the Fermi scale, and that the Fermi constant is related to the Newtonian constant of gravitation.In this framework one may understand the violations of fundamental symmetries by the weak interactions, in particular parity violations, as due to fluctuations of the spacetime geometry at a Planck scale coinciding with the Fermi scale. As a consequence, gravitational phenomena should play a more important role in the microworld, and experimental settings are suggested to test this hypothesis.

Heisenberg uncertainty relation for three canonical observables

on 2014-12-15 3:00pm GMT

Author(s): Spiros Kechrimparis and Stefan Weigert

Uncertainty relations provide fundamental limits on what can be said about the properties of quantum systems. For a quantum particle, the commutation relation of position and momentum observables entails Heisenberg's uncertainty relation. A third observable is presented which satisfies canonical com...

[Phys. Rev. A 90, 062118] Published Mon Dec 15, 2014

Quantum models of classical systems. (arXiv:1412.3971v1 [quant-ph])

on 2014-12-15 7:51am GMT

Authors: Petr Hajicek

Quantum statistical methods that are commonly used for the derivation of classical thermodynamic properties are extended to classical mechanical properties. The usual assumption that every real motion of a classical mechanical system is represented by a sharp trajectory is not testable and is replaced by a class of fuzzy models, the so-called maximum entropy (ME) packets. The fuzzier are the compared classical and quantum ME packets, the better seems to be the match between their dynamical trajectories. Classical and quantum models of a stiff rod will be constructed to illustrate the resulting unified quantum theory of thermodynamic and mechanical properties.

The Standard Model of Particle Physics. (arXiv:1412.4094v1 [physics.hist-ph])

on 2014-12-15 7:50am GMT

Authors: Tom W.B. Kibble

This is a historical account from my personal perspective of the development over the last few decades of the standard model of particle physics. The model is based on gauge theories, of which the first was quantum electrodynamics, describing the interactions of electrons with light. This was later incorporated into the electroweak theory, describing electromagnetic and weak nuclear interactions. The standard model also includes quantum chromodynamics, the theory of the strong nuclear interactions. The final capstone of the model was the Higgs particle discovered in 2012 at CERN. But the model is very far from being the last word; there are still many gaps in our understanding.

Maximum Tension: with and without a cosmological constant. (arXiv:1408.1820v3 [gr-qc] UPDATED)

on 2014-12-14 1:30am GMT

Authors: John D. Barrow, G. W. Gibbons

We discuss various examples and ramifications of the conjecture that there exists a maximum force (or tension) in general relativistic systems. We contrast this situation with that in Newtonian gravity, where no maximum force exists, and relate it to the existence of natural units defined by constants of Nature and the fact that the Planck units of force and power do not depend on Planck's constant. We discuss how these results change in higher dimensions where the Planck units of force are no longer non-quantum. We discuss the changes that might occur to the conjecture if a positive cosmological constant exists and derive a maximum force bound using the Kottler-Schwarzschild-de Sitter black hole.

on 2014-12-14 1:30am GMT

Authors: Amir Etemadi, Kourosh Nozari

We study some fundamental issues related to the Hilbert space representation of quantum mechanics in the presence of a minimal length and maximal momentum. In this framework, the maximally localized states and quasi-position representation introduced by Kempf et al. are reconsidered and modified. We show that all studies in recent years, including [15] and [16] need serious modification in order to be a consistent framework for quantum mechanics in Planck scale.

Bohr’s Philosophy in the Light of Peircean Pragmatism

Latest Results for Journal for General Philosophy of Science

on 2014-12-14 12:00am GMT

Abstract

Adopting Murdoch’s pragmatist reading of Bohr’s theory of meaning with regard to Bohr’s notion of complementarity, in this paper I try to see Bohr’s post-Como and, in particular, post-EPR philosophy of quantum mechanics in the light of Peircean pragmatism with the hope that such a construal can shed more light to Bohr’s philosophy. I supplement Murdoch’s position on Bohr’s pragmatism by showing that in addition to his complementarity, Bohr’s correspondence principle, instrumentalism and realism can be read on the basis of Peirce’s pragmatic maxim and his notion of indeterminism has commonalities with Peirce’s tychism. Also, Bohr’s practice of applying the correspondence principle can be interpreted in the light of Peirce’s fallibilism. However, when it comes to Bohr’s understanding of the symbolic character of quantum mechanics, Bohr’s philosophy deviates from Peircean pragmatism. Bohr’s philosophy distinguishes between the symbolic language of quantum formalism, which counts as a tool practically useful for prediction, and observation sentences which are visualizable in space and time and refer to the so-called individual phenomena. Such an epistemologically significant distinction is not recognized by Peircean pragmatism.

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