Weekly Papers on Quantum Foundations (52)

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.

Quantum Gravitational Force Between Polarizable Objects. (arXiv:1512.07632v1 [hep-th])

gr-qc updates on arXiv.org

on 2015-12-26 6:43am GMT

Authors: L. H. FordMark P. HertzbergJ. Karouby

Since general relativity is a consistent low energy effective field theory, it is possible to compute quantum corrections to classical forces. Here we compute a quantum correction to the gravitational potential between a pair of polarizable objects. We study two distant bodies and compute a quantum force from their induced quadrupole moments due to two graviton exchange. The effect is in close analogy to the Casimir-Polder and London-van der Waals forces between a pair of atoms from their induced dipole moments due to two photon exchange. The new effect is computed from the shift in vacuum energy of metric fluctuations due to the polarizability of the objects. We compute the potential energy at arbitrary distances compared to the wavelengths in the system, including the far and near regimes. In the far distance, or retarded, regime, the potential energy takes on a particularly simple form: $V(r)=-3987\,\hbar\,c\,G^2\alpha_{1S}\,\alpha_{2S}/(4\,\pi\,r^{11})$, where $\alpha_{1S},\,\alpha_{2S}$ are the static gravitational quadrupole polarizabilities of each object. We provide estimates of this effect.

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Matters of Gravity, The Newsletter of the Topical Group on Gravitation of the American Physical Society, Volume 46, December 2015. (arXiv:1512.07646v1 [gr-qc])

gr-qc updates on arXiv.org

on 2015-12-26 6:43am GMT

Authors: David Garfinkle

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Quantum Information in Quantum Gravity

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Quantum superposition at the half-metre scale

Nature Latest Research

on 2015-12-23 12:00am GMT

The quantum superposition principle allows massive particles to be delocalized over distant positions. Though quantum mechanics has proved adept at describing the microscopic world, quantum superposition runs counter to intuitive conceptions of reality and locality when extended to the macroscopic scale, as exemplified by the thought experiment of Schrödinger’s cat. Matter-wave interferometers, which split and recombine wave packets in order to observe interference, provide a way to probe the superposition principle on macroscopic scales and explore the transition to classical physics. In such experiments, large wave-packet separation is impeded by the need for long interaction times and large momentum beam splitters, which cause susceptibility to dephasing and decoherence. Here we use light-pulse atom interferometry to realize quantum interference with wave packets separated by up to 54 centimetres on a timescale of 1 second. These results push quantum superposition into a new macroscopic regime, demonstrating that quantum superposition remains possible at the distances and timescales of everyday life. The sub-nanokelvin temperatures of the atoms and a compensation of transverse optical forces enable a large separation while maintaining an interference contrast of 28 per cent. In addition to testing the superposition principle in a new regime, large quantum superposition states are vital to exploring gravity with atom interferometers in greater detail. We anticipate that these states could be used to increase sensitivity in tests of the equivalence principle, measure the gravitational Aharonov–Bohm effect, and eventually detect gravitational waves and phase shifts associated with general relativity.

Nature 528 530 doi: 10.1038/nature16155

Outline of a Generalization and a Reinterpretation of Quantum Mechanics Recovering Objectivity

Latest Results for International Journal of Theoretical Physics

on 2015-12-21 12:00am GMT

Abstract

The ESR model has been recently proposed in several papers to offer a possible solution to the problems raising from the nonobjectivity of physical properties in quantum mechanics (QM) (mainly the objectification problem of the quantum theory of measurement). This solution is obtained by embodying the mathematical formalism of QM into a broader mathematical framework and reinterpreting quantum probabilities as conditional on detection rather than absolute. We provide a new and more general formulation of the ESR model and discuss time evolution according to it, pointing out in particular that both linear and nonlinear evolution may occur, depending on the physical environment.

 

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