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Determining the Quantum Expectation Value by Measuring a Single Photon: The first realisation of quantum protective measurements

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F. Piacentini, A. Avella, E. Rebufello, R. Lussana, F. Villa, A. Tosi, M. Gramegna, G. Brida, E. Cohen, L. Vaidman, I. P. Degiovanni, M. Genovese Quantum mechanics, one of the keystones of modern physics, exhibits several peculiar properties, differentiating it from classical mechanics. One of the most intriguing is that variables might not have definite values. A complete quantum description provides only probabilities for obtaining various eigenvalues of a quantum variable…. Read more →

Weekly Papers on Quantum Foundations (33)

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No smooth beginning for spacetime. (arXiv:1705.00192v2 [hep-th] UPDATED)  gr-qc updates on arXiv.org on 2017-8-19 8:40am GMT Authors: Job Feldbrugge, Jean-Luc Lehners, Neil Turok We identify a fundamental obstruction to any theory of the beginning of the universe, formulated as a semiclassical path integral. Hartle and Hawking’s no boundary proposal and Vilenkin’s tunneling proposal are examples of such theories. Each may be formulated as… Read more →

Weekly Papers on Quantum Foundations (32)

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Adiabatic Theorem for Quantum Spin Systems  PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. on 2017-8-11 2:00pm GMT Author(s): S. Bachmann, W. De Roeck, and M. Fraas The first proof of the quantum adiabatic theorem was given as early as 1928. Today, this theorem is increasingly applied in a many-body context, e.g., in quantum annealing and in studies… Read more →

Weekly Papers on Quantum Foundations (31)

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Imaging Uncertainty  Philsci-Archive: No conditions. Results ordered -Date Deposited. on 2017-8-04 7:15pm GMT Eva, Benjamin and Hartmann, Stephan (2017) Imaging Uncertainty. [Preprint] The Chances of Propensities  Philsci-Archive: No conditions. Results ordered -Date Deposited. on 2017-8-04 7:14pm GMT Suárez, Mauricio (2016) The Chances of Propensities. [Preprint] The Relativistic Einstein-Podolsky-Rosen Argument  Philsci-Archive: No conditions. Results ordered -Date Deposited. on 2017-8-04 7:11pm GMT… Read more →

Weekly Papers on Quantum Foundations (30)

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What can (mathematical) categories tell us about space-time?  Philsci-Archive: No conditions. Results ordered -Date Deposited. on 2017-7-28 8:23pm GMT Sanders, Ko (2015) What can (mathematical) categories tell us about space-time? In: UNSPECIFIED. Time Symmetric Quantum Theory Without Retrocausality. (arXiv:1707.08641v1 [quant-ph])  quant-ph updates on arXiv.org on 2017-7-28 2:25am GMT Authors: Tim Maudlin In their recent paper “Is a Time Symmetric Interpretation of… Read more →

Weekly Papers on Quantum Foundations (29)

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Spacetime and Physical Equivalence   Fundamental limits on quantum dynamics based on entropy change. (arXiv:1707.06584v1 [quant-ph])  quant-ph updates on arXiv.org on 2017-7-21 2:13am GMT Authors: Siddhartha Das, Sumeet Khatri, George Siopsis, Mark M. Wilde It is well known in the realm of quantum mechanics and information theory that the entropy is non-decreasing for the class of unital physical processes. However, in general, the entropy… Read more →

Weekly Papers on Quantum Foundations (28)

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Resolving the observer reference class problem in cosmology  Philsci-Archive: No conditions. Results ordered -Date Deposited. on 2017-7-14 7:20pm GMT Friederich, Simon (2017) Resolving the observer reference class problem in cosmology. Physical Review D, 95 (12). p. 123520. Symmetries and the identity of physical states  Philsci-Archive: No conditions. Results ordered -Date Deposited. on 2017-7-14 7:14pm GMT Friederich, Simon (2016) Symmetries and… Read more →

Weekly Papers on Quantum Foundations (27)

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Thermodynamics as a Consequence of Information Conservation. (arXiv:1707.01750v1 [quant-ph])  quant-ph updates on arXiv.org on 2017-7-07 8:21am GMT Authors: Manabendra Nath Bera, Arnau Riera, Maciej Lewenstein, Andreas Winter In this work we formulate thermodynamics as an exclusive consequence of information conservation. The framework can be applied to most general situations, beyond the traditional assumptions in thermodynamics, where systems and thermal-baths could be quantum, of arbitrary… Read more →

Duration and its relation to the structure of space-time II

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Andreas Schlatter We assign to the radiation vacuum the role of a universal observer with a corresponding universal clock. By demanding that the thermal clock of a gravitationally accelerated observer in its local rest frame marches in step with the universal one, we derive relations between energy content and geometry of space-time. Full text

Quantum jumps and electrodynamical description

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Leonardo Chiatti (ASL VT Medical Physics Laboratory) The customary description of radiation processes provided by Quantum Electrodynamics (QED) allows the quantitative derivation of many physical observables, in line with experiments. This extraordinary empirical success, however, leaves open the problem of the ontology of these processes. We identify these with the discontinuities of the evolution of the quantum state of the… Read more →

Weekly Papers on Quantum Foundations (26)

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Simple derivation of the Weyl and Dirac quantum cellular automata  PRA: Quantum information on 2017-6-30 2:00pm GMT Author(s): Philippe Raynal We consider quantum cellular automata on a body-centered cubic lattice and provide a simple derivation of the only two homogenous, local, isotropic, and unitary two-dimensional automata [G. M. D’Ariano and P. Perinotti,Phys. Rev. A 90, 062106 (2014)]. Our derivation relies on… Read more →