Weekly Papers on Quantum Foundations (2)

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.

Why are Casimir energy differences so often finite?. (arXiv:1601.01374v1 [quant-ph])

hep-th updates on arXiv.org

on 2016-1-08 8:58am GMT

Authors: Matt Visser (Victoria University of Wellington)

One of the very first applications of the quantum field theoretic vacuum state was in the development of the notion of Casimir energy. Now field theoretic Casimir energies, considered individually, are always infinite. But differences in Casimir energies are quite often finite — a fortunate circumstance which luckily made some of the early calculations, (for instance, for parallel plates and hollow spheres), tolerably tractable. We shall explore the extent to which this observation can be systematised. For instance: What are necessary and sufficient conditions for Casimir energy differences to be finite? When the Casimir energy differences are not finite, can anything useful be said? We shall see that it is the difference in the first few Seeley-DeWitt coefficients that is central to answering these questions. In particular, for any collection of conductors (perfect or imperfect) and/or dielectrics, as long as one merely moves them around without changing shape or volume, then the Casimir energy difference (and so the Casimir forces) are guaranteed finite.

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Measurement-induced macroscopic superposition states in cavity optomechanics. (arXiv:1601.01663v1 [quant-ph])

quant-ph updates on arXiv.org

on 2016-1-08 8:58am GMT

Authors: Ulrich B. HoffJohann Kollath-BönigJonas S. Neergaard-NielsenUlrik L. Andersen

We present a novel proposal for generating quantum superpositions of macroscopically distinct states of a bulk mechanical oscillator, compatible with existing optomechanical devices operating in the readily achievable bad-cavity limit. The scheme is based on a pulsed cavity optomechanical quantum non-demolition (QND) interaction, driven by displaced non-Gaussian states, and measurement-induced feedback, avoiding the need for strong single-photon optomechanical coupling. Furthermore, we show that single-quadrature cooling of the mechanical oscillator is sufficient for efficient state preparation, and we outline a three-pulse protocol comprising a sequence of QND interactions for squeezing-enhanced cooling, state preparation, and tomography.

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Quantum mechanics: The lone traveller

Nature Physics – Issue – nature.com science feeds

on 2016-1-07 12:00am GMT

Nature Physics 12, 20 (2016). doi:10.1038/nphys3635

Author: Abigail Klopper

Strongly enhanced effects of Lorentz symmetry violation in entangled Yb+ ions

Nature Physics – AOP – nature.com science feeds

on 2016-1-04 12:00am GMT

Nature Physics. doi:10.1038/nphys3610

Authors: V. A. Dzuba, V. V. Flambaum, M. S. Safronova, S. G. Porsev, T. Pruttivarasin, M. A. Hohensee & H. Häffner

A number of theories aiming at unifying gravity with other fundamental interactions, including field theory, suggest the violation of Lorentz symmetry. Whereas the energy scale of such strongly Lorentz-symmetry-violating physics is much higher than that attainable at present by particle accelerators, Lorentz violation may nevertheless be detectable via precision measurements at low energies. Here, we carry out a systematic theoretical investigation to identify which atom shows the greatest promise for detecting a Lorentz symmetry violation in the electron–photon sector. We found that the ytterbium ion (Yb+) is an ideal system with high sensitivity, as well as excellent experimental controllability. By applying quantum-information-inspired technology to Yb+, we expect tests of local Lorentz invariance (LLI) violating physics in the electron–photon sector to reach levels of 10−23—five orders of magnitude more sensitive than the current best bounds.

Quantum States as Informational Bridges

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

on 2016-1-03 6:36pm GMT

Healey, Richard A. (2015) Quantum States as Informational Bridges. [Preprint]

 

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