Weekly Papers on Quantum Foundations (13)

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.

A Survey of the ESR Model for an Objective Reinterpretation of Quantum Mechanics

Latest Results for International Journal of Theoretical Physics

on 2015-3-28 12:00am GMT

Abstract

Contextuality and nonlocality (hence nonobjectivity of physical properties) are usually maintained to be unavoidable features of quantum mechanics (QM), following from its mathematical apparatus. Moreover they are considered as basic in quantum information processing. Nevertheless they raise still unsolved problems, as the objectification problem in the quantum theory of measurement. The extended semantic realism (ESRmodel offers a way out from these difficulties by reinterpreting quantum probabilities as conditional rather than absolute and embedding the mathematical formalism of QM into a broader mathematical framework. A noncontextual hidden variables theory can then be constructed which justifies the assumptions introduced in the ESR model and proves its objectivity. Both linear and nonlinear time evolution occur in this model, depending on the physical environment, as in QM. In addition, the ESR model implies modified Bell’s inequalities that do not necessarily conflict with QM, supplies different mathematical representations of proper and improper mixtures, provides a general framework in which the local interpretations of the GHZ experiment obtained by other authors are recovered, and supports an interpretation of quantum logic which avoids the introduction of the problematic notion of quantum truth.

The holographic quantum. (arXiv:1503.07662v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-3-27 12:53am GMT

Authors: P. Fernandez de CordobaJ.M. IsidroJ. Vazquez Molina

We present a holographic-like map of standard quantum mechanics (the bulk theory) onto a dual theory, that of the classical thermodynamics of irreversible processes (the boundary theory).

Quantum mechanics, strong emergence and ontological non-reducibility

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

on 2015-3-26 6:29pm GMT

Gambini, Rodolfo and Lewowicz, Lucia and Pullin, Jorge (2013) Quantum mechanics, strong emergence and ontological non-reducibility. [Preprint]

The Observer Strikes Back. (arXiv:1503.07205v1 [gr-qc])

quant-ph updates on arXiv.org

on 2015-3-26 3:57am GMT

Authors: James Hartle (UCSB), Thomas Hertog (KULeuven)

In the modern quantum mechanics of cosmology observers are physical systems within the universe. They have no preferred role in the formulation of the theory nor in its predictions of third person probabilities of what occurs. However, observers return to importance for the prediction of first person probabilities for what we observe of the universe: What is most probable to be observed is not necessarily what is most probable to occur. This essay reviews the basic framework for the computation of first person probabilities in quantum cosmology starting with an analysis of very simple models. It is shown that anthropic selection is automatic in this framework, because there is no probability for us to observe what is where we cannot exist. First person probabilities generally favor larger universes resulting from inflation where there are more places for us to be. In very large universes it is probable that our observational situation is duplicated elsewhere. The calculation of first person probabilities then requires a specification of whether our particular situation is assumed to be typical of all the others. It is the combination of the model of the observational situation, including this typicality assumption, and the third person theory which is tested by observation. We conclude with a discussion of the first person predictions of cosmological observables such as the cosmological constant and features of the primordial density fluctuations, in the no-boundary quantum state of the universe and a dynamical theory in which these are allowed to vary.

On the quantum corrected gravitational collapse. (arXiv:1503.07407v1 [gr-qc])

gr-qc updates on arXiv.org

on 2015-3-26 3:56am GMT

Authors: Ramon TorresFrancesc Fayos

Based on a previously found general class of quantum improved exact solutions composed of non-interacting (dust) particles, we model the gravitational collapse of stars. As the modeled star collapses a closed apparent 3-horizon is generated due to the consideration of quantum effects. The effect of the subsequent emission of Hawking radiation related to this horizon is taken into consideration. Our computations lead us to argue that a total evaporation could be reached. The inferred global picture of the spacetime corresponding to gravitational collapse is devoid of both event horizons and shell-focusing singularities. As a consequence, there is no information paradox and no need of firewalls.

Correspondence Truth and Quantum Mechanics

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

on 2015-3-25 6:38pm GMT

Karakostas, Vassilios (2014) Correspondence Truth and Quantum Mechanics. [Published Article]

Reply to Norsen’s paper “Are there really two different Bell’s theorems?”. (arXiv:1503.06978v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-3-25 2:37am GMT

Authors: Howard M. WisemanEleanor G. Rieffel

Yes. That is my polemical reply to the titular question in Travis Norsen’s self-styled “polemical response to Howard Wiseman’s recent paper.” Less polemically, I am pleased to see that on two of my positions — that Bell’s 1964 theorem is different from Bell’s 1976 theorem, and that the former does not include Bell’s one-paragraph heuristic presentation of the EPR argument — Norsen has made significant concessions. In his response, Norsen admits that “Bell’s recapitulation of the EPR argument in [the relevant] paragraph leaves something to be desired,” that it “disappoints” and is “problematic”. Moreover, Norsen makes other statements that imply, on the face of it, that he should have no objections to the title of my recent paper (“The Two Bell’s Theorems of John Bell”). My principle aim in writing that paper was to try to bridge the gap between two interpretational camps, whom I call ‘operationalists’ and ‘realists’, by pointing out that they use the phrase “Bell’s theorem” to mean different things: his 1964 theorem (assuming locality and determinism) and his 1976 theorem (assuming local causality), respectively. Thus, it is heartening that at least one person from one side has taken one step on my bridge. That said, there are several issues of contention with Norsen, which we (the two authors) address after discussing the extent of our agreement with Norsen. The most significant issues are: the indefiniteness of the word ‘locality’ prior to 1964; and the assumptions Einstein made in the paper quoted by Bell in 1964 and their relation to Bell’s theorem.

Non-local beables

International Journal of Quantum Foundations » International Journal of Quantum Foundations

on 2015-3-25 2:15am GMT

Volume 1, Issue 2, pages 100-106

Lee Smolin [Show Biography]

Born in New York City, Prof. Lee Smolin was educated at Hampshire College and Harvard University. He was formerly a professor at Yale, Syracuse and Penn State Universities and held postdoctoral positions at the Institute for Advanced Study, Princeton, the Institute for Theoretical Physics, Santa Barbara and the Enrico Fermi Institute, the University of Chicago. He has been a visiting professor at Imperial College London and has held various visiting positions at Oxford and Cambridge Universities and the Universities of Rome and Trento, and SISSA, in Italy. Since 2001, he has been a founding and senior faculty member at Perimeter Institute for Theoretical Physics. Prof. Smolin works mainly on the problem of quantum gravity. He also has contributed to cosmology, the foundations of quantum mechanics, astrophysics, theoretical biology, philosophy of science and, recently, economics.

I discuss the idea that the beables underlying quantum physics are non-local and relational, and give an example of a dynamical theory of such beables based on a matrix model, which is the bosonic sector of the BFSS model. Given that the same model has been proposed as a description of M theory, this shows that quantum mechanics may be emergent from a theory of gravity from which space is also emergent.

Full Text Download (201k) | View Submission Post

Local Hidden Variable Models for Entangled Quantum States Using Finite Shared Randomness

PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

on 2015-3-24 2:00pm GMT

Author(s): Joseph Bowles, Flavien Hirsch, Marco Túlio Quintino, and Nicolas Brunner

The statistics of local measurements performed on certain entangled states can be reproduced using a local hidden variable (LHV) model. While all known models make use of an infinite amount of shared randomness, we show that essentially all entangled states admitting a LHV model can be simulated wit…

[Phys. Rev. Lett. 114, 120401] Published Tue Mar 24, 2015

Reply to Norsen’s paper “Are there really two different Bell’s theorems?”

International Journal of Quantum Foundations » International Journal of Quantum Foundations

on 2015-3-24 3:28am GMT

Volume 1, Issue 2, pages 85-99

Howard M. Wiseman [Show Biography] and Eleanor G. Rieffel [Show Biography]

Howard Wiseman is a theoretical physicist known for his work in quantum foundations, quantum information, and quantum measurement and control. He did his BSc Hons (1991) and PhD (1992-4) with Gerard Milburn at the University of Queensland, and a postdoc (1994-6) with Dan Walls FRS at the University of Auckland. He has published over 200 refereed papers, and a 2010 Cambridge textbook (with Milburn). He has won the Bragg Medal (AIP), the Pawsey Medal (AAS), and the Malcolm Macintosh Medal (PM’s science prizes). He is a Fellow of the AAS, and of the American Physical Society. He has been Director of the Centre for Quantum Dynamics at Griffith University since 2007.

Eleanor G. Rieffel explores algorithm design and fundamental questions in quantum computation as a leader of NASA’s QuAIL team. After receiving her Ph.D. in mathematics from UCLA, and serving as a mathematics post-doc at USC, she joined FXPAL where she performed research in diverse fields including quantum computation, applied cryptography, bioinformatics, and robotics. She joined NASA Ames Research Center in 2012 to work on their expanding quantum computing effort. Her book, Quantum Computing: A Gentle Introduction, with coauthor Wolfgang Polak was published by MIT press in the spring of 2011, and has received stellar reviews.

Yes. That is my polemical reply to the titular question in Travis Norsen’s self-styled “polemical response to Howard Wiseman’s recent paper.” Less polemically, I am pleased to see that on two of my positions — that Bell’s 1964 theorem is different from Bell’s 1976 theorem, and that the former does not include Bell’s one-paragraph heuristic presentation of the EPR argument — Norsen has made significant concessions. In his response, Norsen admits that “Bell’s recapitulation of the EPR argument in [the relevant] paragraph leaves something to be desired,” that it “disappoints” and is “problematic”. Moreover, Norsen makes other statements that imply, on the face of it, that he should have no objections to the title of my recent paper (“The Two Bell’s Theorems of John Bell”). My principle aim in writing that paper was to try to bridge the gap between two interpretational camps, whom I call ‘operationalists’ and ‘realists’, by pointing out that they use the phrase “Bell’s theorem” to mean different things: his 1964 theorem (assuming locality and determinism) and his 1976 theorem (assuming local causality), respectively. Thus, it is heartening that at least one person from one side has taken one step on my bridge. That said, there are several issues of contention with Norsen, which we (the two authors) address after discussing the extent of our agreement with Norsen. The most significant issues are: the indefiniteness of the word ‘locality’ prior to 1964; and the assumptions Einstein made in the paper quoted by Bell in 1964 and their relation to Bell’s theorem.

Full Text Download (176k) | View Submission Post

T violation and the Unidirectionality of Time: further details of the interference. (arXiv:1503.06523v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-3-24 1:56am GMT

Authors: Joan A. Vaccaro

T violation has previously been shown to induce destructive interference between different paths that the universe can take through time and leads to a new quantum equation of motion called bievolution. Here we examine further details of the interference and clarify the conditions needed for the bievolution equation.

Causarum Investigatio and the Two Bell’s Theorems of John Bell. (arXiv:1503.06413v1 [quant-ph])

quant-ph updates on arXiv.org

on 2015-3-24 1:56am GMT

Authors: Howard M. WisemanEric G. Cavalcanti

“Bell’s theorem” can refer to two different theorems that John Bell proved, the first in 1964 and the second in 1976. His 1964 theorem is the incompatibility of quantum phenomena with the joint assumptions of Locality and Predetermination. His 1976 theorem is their incompatibility with the single property of Local Causality. This is contrary to Bell’s own later assertions, that his 1964 theorem began with the assumption of Local Causality, even if not by that name. Although the two Bell’s theorems are logically equivalent, their assumptions are not. Hence, the earlier and later theorems suggest quite different conclusions, embraced by operationalists and realists, respectively. The key issue is whether Locality or Local Causality is the appropriate notion emanating from Relativistic Causality, and this rests on one’s basic notion of causation. For operationalists the appropriate notion is what is here called the Principle of Agent-Causation, while for realists it is Reichenbach’s Principle of common cause. By breaking down the latter into even more basic Postulates, it is possible to obtain a version of Bell’s theorem in which each camp could reject one assumption, happy that the remaining assumptions reflect its weltanschauung. Formulating Bell’s theorem in terms of causation is fruitful not just for attempting to reconcile the two camps, but also for better describing the ontology of different quantum interpretations and for more deeply understanding the implications of Bell’s marvellous work.

Holographic quantum error-correcting codes: Toy models for the bulk/boundary correspondence. (arXiv:1503.06237v1 [hep-th])

quant-ph updates on arXiv.org

on 2015-3-24 1:56am GMT

Authors: Fernando PastawskiBeni YoshidaDaniel HarlowJohn Preskill

We propose a family of exactly solvable toy models for the AdS/CFT correspondence based on a novel construction of quantum error-correcting codes with a tensor network structure. Our building block is a special type of tensor with maximal entanglement along any bipartition, which gives rise to an exact isometry from bulk operators to boundary operators. The entire tensor network is a quantum error-correcting code, where the bulk and boundary degrees of freedom may be identified as logical and physical degrees of freedom respectively. These models capture key features of entanglement in the AdS/CFT correspondence; in particular, the Ryu-Takayanagi formula and the negativity of tripartite information are obeyed exactly in many cases. That bulk logical operators can be represented on multiple boundary regions mimics the Rindler-wedge reconstruction of boundary operators from bulk operators, realizing explicitly the quantum error-correcting features of AdS/CFT recently proposed by Almheiri et. al in arXiv:1411.7041.

Laws of nature and the reality of the wave function

Latest Results for Synthese

on 2015-3-24 12:00am GMT

Abstract

In this paper I review three different positions on the wave function, namely: nomological realism, dispositionalism, and configuration space realism by regarding as essential their capacity to account for the world of our experience. I conclude that the first two positions are committed to regard the wave function as an abstract entity. The third position will be shown to be a merely speculative attempt to derive a primitive ontology from a reified mathematical space. Without entering any discussion about nominalism, I conclude that the elimination of abstract entities from one’s ontology commits one to instrumentalism about the wave function, a position that therefore is not as unmotivated as it has seemed to be to many philosophers.

A quantum advantage for inferring causal structure

Nature Physics – AOP – nature.com science feeds

on 2015-3-23 12:00am GMT

Nature Physics. doi:10.1038/nphys3266

Authors: Katja Ried, Megan Agnew, Lydia Vermeyden, Dominik Janzing, Robert W. Spekkens & Kevin J. Resch

Space and Time in a Quantized World

Latest Results for International Journal of Theoretical Physics

on 2015-3-22 12:00am GMT

Abstract

Rather than consider space-time as an a priori arena in which events take place, it is a construction of our mind making possible a particular kind of ordering of events. As quantum entanglement is a property of states independent of classical distances, the notion of space and time has to be revised to represent the holistic interconnectedness of quanta. We also speculate about various forms of reprogramming, or reconfiguring, the propagation of information for multipartite statistics and in quantum field theory.

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