Weekly Papers on Quantum Foundations (2)

 上午10:07 | Johanna Erdmenger, Kevin T. Grosvenor, Ro Jefferson | quant-ph updates on arXiv.org

Motivated by the increasing connections between information theory and high-energy physics, particularly in the context of the AdS/CFT correspondence, we explore the information geometry associated to a variety of simple systems. By studying their Fisher metrics, we derive some general lessons that may have important implications for the application of information geometry in holography. We begin by demonstrating that the symmetries of the physical theory under study play a strong role in the resulting geometry, and that the appearance of an AdS metric is a relatively general feature. We then investigate what information the Fisher metric retains about the physics of the underlying theory by studying the geometry for both the classical 2d Ising model and the corresponding 1d free fermion theory, and find that the curvature diverges precisely at the phase transition on both sides. We discuss the differences that result from placing a metric on the space of theories vs. states, using the example of coherent free fermion states. We also clarify some misconceptions in the literature pertaining to different notions of flatness associated to metric and non-metric connections, with implications for how one interprets the curvature of the geometry. Our results indicate that in general, caution is needed when connecting the AdS geometry arising from certain models with the AdS/CFT correspondence, and seek to provide a useful collection of guidelines for future progress in this exciting area.

 上午10:07 | Chiara Marletto, Vlatko Vedral | quant-ph updates on arXiv.org

We use a quantum variant of the Sagnac interferometer to argue for the quantum nature of gravity as well as to formulate a quantum version of the equivalence principle. We first present an original derivation of the phase acquired in the conventional Sagnac matter-wave interferometer, within the Hamiltonian formalism. Then we modify the interferometer in two crucial respects. The interfering matter wave is interfered along two different distances from the centre and the interferometer is prepared in a superposition of two different angular velocities. We argue that if the radial and angular degrees of freedom of the matter wave become entangled through this experiment, then, via the equivalence principle, the gravitational field must be non-classical.

In the early 2000s, the study of time operators advanced as one of the methods to understand the problem of time as mathematical science. However, the starting point for the time operator is to understand time as a problem of observation (the survival probabilityof particles), and today, even after the issue of representation on time operator has concluded, the question of philosophical interpretation still exists. Furthermore, when it comes to the question of how time generation (emergence), the method of time operators has its limitations. Regarding the generation of time, symmetry breaking in particle physics seems to be closely related.

 上午10:07 | DaeKil Park, Eylee Jung | quant-ph updates on arXiv.org

The non-relativistic quantum mechanics with the generalized uncertainty principle (GUP) is examined when the potential is one-dimensional $\delta-$function. It is shown that unlike usual quantum mechanics, the Schr\”{o}dinger and Feynman’s path-integral approaches are inequivalent at the first order of GUP parameter.

 上午10:07 | physics.hist-ph updates on arXiv.org

Authors: Kavan Modi

These are my recollections of working with George Sudarshan from 2002 to 2008 when I was a PhD student in his group. During these years I learnt a lot of physics and also witness to some remarkable occurrences.

 上午10:07 | physics.hist-ph updates on arXiv.org

Authors: Andrei Khrennikov

This paper is a new step towards getting rid of nonlocality from quantum physics. This is an attempt to structure the nonlocality mess. “Quantum nonlocality” is Janus faced. One its face is projection (Einstein-L\”uders) nonlocality and another Bell nonlocality. The first one is genuine quantum nonlocality, the second one is subquantum nonlocality. Recently it was shown that Bell “nonlocality” is a simple consequence of the complementarity principle. We now show that projection nonlocality has no connection with physical space. Projection state update is generalization of the well known operation of probability update used in classical inference. We elevate the role of interpretations of a quantum state. By using the individual (physical) interpretation, one can really get the illusion of a spooky action at a distance resulting from L\”uders’ state update. The statistical interpretation combined with treating the quantum formalism as machinery for update of probability is known as the V\”axj\”o interpretation. Here one follows the standard scheme of probability update adjusted to the quantum calculus of probability. The latter is based on operating with states represented by vectors (or density operators). We present in parallel classical and quantum probability updates. From this presentation, it is clear that both classical and quantum “faster-than-light change of statistical correlation” take place in mental and not physical space.

Authors: Igor Salom

The “measurement problem” of quantum mechanics, and the “hard problem” of cognitive science are the most profound open problems of the two research fields, and certainly among the deepest of all unsettled conundrums in contemporary science in general. Occasionally, scientists from both fields have suggested some sort of interconnectedness of the two problems. Here we revisit the main motives behind such expectations and try to put them on more formal grounds. We argue not only that such a relation exists, but that it also bears strong implications both for the interpretations of quantum mechanics and for our understanding of consciousness. The paper consists of three parts. In the first part, we formulate a “no-go-theorem” stating that a brain, functioning solely on the principles of classical physics, cannot have any greater ability to induce subjective experience than a process of writing (printing) a certain sequence of digits. The goal is to show, with an attempt to mathematical rigor, why the physicalist standpoint based on classical physics is not likely to ever explain the phenomenon of consciousness — justifying the tendency to look beyond the physics of the 19th century. In the second part, we aim to establish a clear relation, with a sort of correspondence mapping, between attitudes towards the hard problem and interpretations of quantum mechanics. Then we discuss these connections in the light of the no-go theorem, pointing out that the existence of subjective experience might differentiate between otherwise experimentally indistinguishable interpretations. Finally, the third part is an attempt to illustrate how quantum mechanics could take us closer to the solution of the hard problem and break the constraints set by the no-go theorem.

Authors: Rodolfo GambiniEsteban MatoJorge Pullin

In a previous paper we formulated axisymmetric general relativity in terms of real Ashtekar–Barbero variables. Here we proceed to quantize the theory. We are able to implement Thiemann’s version of the Hamiltonian constraint. We discuss its action including the matrix elements and its solutions. This provides a 2+1 dimensional arena to test ideas for the dynamics of quantum gravity and opens the possibility of quantum studies of rotating black hole spacetimes.

 上午10:07 | gr-qc updates on arXiv.org

Authors: Koji AzumaGo Kato

If simple entropy in the Bekenstein-Hawking area law for a black hole is replaced with ‘negative’ quantum conditional entropy, which quantifies quantum entanglement, of positive-energy particles of the black hole relative to its outside, a paradox with the original pair-creation picture of Hawking radiation, the first law for black hole mechanics and quantum mechanics is resolved. However, there was no way to judge experimentally which area law is indeed adopted by black holes. Here, with the no-hair conjecture, we derive the perfect picture of a second law of black hole thermodynamics from the modified area law, rather than Bekenstein’s generalized one from the original area law. The second law is testable with an event horizon telescope, in contrast to Bekenstein’s. If this is confirmed, the modified area law is exalted to the first example of fundamental equations in physics which cannot be described without the concept of quantum information.

 2020年1月10日 星期五 上午8:51 | C.-F. Li, G.-C. Guo, J. Piilo | quant-ph updates on arXiv.org

Recent developments in practical quantum engineering and control techniques have allowed significant developments for experimental studies of open quantum systems and decoherence engineering. Indeed, it has become possible to test experimentally various theoretical, mathematical, and physical concepts related to non-Markovian quantum dynamics. This includes experimental characterization and quantification of non-Markovian memory effects and proof-of-principle demonstrations how to use them for certain quantum communication and information tasks. We describe here recent experimental advances for open system studies, focussing in particular to non-Markovian dynamics including the applications of memory effects, and discuss the possibilities for ultimate control of decoherence and open system dynamics.

 2020年1月10日 星期五 上午8:51 | C.-F. Li, G.-C. Guo, J. Piilo | quant-ph updates on arXiv.org

During the last ten years, the studies on non-Markovian open system dynamics has become increasingly popular and having contributions from diverse set of research communities. This interest has arisen due to fundamental problematics how to define and quantify memory effects in the quantum domain, how to exploit and develop applications based on them, and also due to the question what are the ultimate limits for controlling open system dynamics. We give here a simple theoretical introduction to the basic approaches to define and quantify quantum non-Markovianity — also highlighting their connections and differences. In addition to the importance of the development for open quantum systems studies, we also discuss the implications of the progress for other fields including, e.g., formal studies of stochastic processes and quantum information science, and conclude with possible future directions the recent developments open.

 2020年1月10日 星期五 上午8:51 | Germain Tobar, Fabio Costa | quant-ph updates on arXiv.org

The theory of general relativity predicts the existence of closed time-like curves (CTCs), which theoretically would allow an observer to travel back in time and interact with their past self. This raises the question of whether this could create a grandfather paradox, in which the observer interacts in such a way to prevent their own time travel. Previous research has proposed a framework for deterministic, reversible, dynamics in the presence of CTCs, where observers in distinct regions of spacetime can perform arbitrary local operations with no contradiction arising. However, only scenarios with up to three regions have been fully characterised, revealing only one type of process where the observers can verify to both be in the past and future of each other. Here we extend this characterisation to an arbitrary number of regions and find that there exist several inequivalent processes that can only arise in the presence of CTCs. This supports the view that complex dynamics is possible in the presence of CTCs, compatible with free choice of local operations and free of inconsistencies.

 2020年1月10日 星期五 上午8:51 | physics.hist-ph updates on arXiv.org

Authors: Mario KrennAnton Zeilinger

The vast and growing number of publications in all disciplines of science cannot be comprehended by a single human researcher. As a consequence, researchers have to specialize in narrow sub-disciplines, which makes it challenging to uncover scientific connections beyond the own field of research. Thus access to structured knowledge from a large corpus of publications could help pushing the frontiers of science. Here we demonstrate a method to build a semantic network from published scientific literature, which we call SemNet. We use SemNet to predict future trends in research and to inspire new, personalized and surprising seeds of ideas in science. We apply it in the discipline of quantum physics, which has seen an unprecedented growth of activity in recent years. In SemNet, scientific knowledge is represented as an evolving network using the content of 750,000 scientific papers published since 1919. The nodes of the network correspond to physical concepts, and links between two nodes are drawn when two physical concepts are concurrently studied in research articles. We identify influential and prize-winning research topics from the past inside SemNet thus confirm that it stores useful semantic knowledge. We train a deep neural network using states of SemNet of the past, to predict future developments in quantum physics research, and confirm high quality predictions using historic data. With the neural network and theoretical network tools we are able to suggest new, personalized, out-of-the-box ideas, by identifying pairs of concepts which have unique and extremal semantic network properties. Finally, we consider possible future developments and implications of our findings.

Authors: J. A. S. LimaR. C. Santos

We are experiencing a period of extreme intellectual effervescence in the area of cosmology. A huge volume of observational data in unprecedented quantity and quality and a more consistent theoretical framework propelled cosmology to an era of precision, turning the discipline into a cutting-edge area of contemporary science. Observations with type Ia Supernovae (SNe Ia), showed that the expanding Universe is accelerating, an unexplained fact in the traditional decelerated model. Identifying the cause of this acceleration is the most fundamental problem in the area. As in the scientific renaissance, the solution will guide the course of the discipline in the near future and the possible answers (whether dark energy, some extension of general relativity or a still unknown mechanism) should also leverage the development of physics. In this context, without giving up a pedagogical approach, we present an overview of both the main theoretical results and the most significant observational discoveries of cosmology in the last 100 years. The saga of cosmology will be presented in a trilogy. In this article (Part I), based on the articles by Einstein, de Sitter, Friedmann, Lema\^itre and Hubble, we will describe the period between the origins of cosmology and the discovery of Universal expansion (1929). In Part II, we will see the period from 1930 to 1997, closing with the old standard decelerated model. The Part III will be entirely devoted to the accelerated model of the universe, the cosmic paradigm of the XXI century.

 2020年1月10日 星期五 上午8:51 | gr-qc updates on arXiv.org

Authors: Murat Özer

We first investigate the form the General Relativity Theory would have taken had the gravitational mass and the inertial mass of material objects been different. We then extend this analysis to electromagnetism and postulate an equivalence principle for the electromagnetic field. We argue that to each particle with a different electric charge-to-mass ratio in superimposed gravitational and electromagnetic fields there corresponds a spacetime manifold whose metric tensor $g_{\mu\nu}$ describes the dynamical actions of gravitation and electromagnetism. The electric field outside a charged sphere asserts itself independently rather than contributing to the gravitational field. The contribution of the electric field to the spacetime metric outside the charged sphere is shown to be similar to the gravitational one in the Schwartzschild metric but with a charge-to-mass ratio dependence of the test particle instead of the Reissner – Nordstr\”om metric, resulting in a unified description of gravitation and electromagnetism. We point out that there are existing experiments whose results can be explained by the equivalence principle for the electromagnetic field presented here. Additional experimental predictions of the theory are mentioned.

 2020年1月10日 星期五 上午8:00 | Latest Results for Synthese

Abstract

Weyl’s tile argument purports to show that there are no natural distance functions in atomistic space that approximate Euclidean geometry. I advance a response to this argument that relies on a new account of distance in atomistic space, called the mixed account, according to which local distances are primitive and other distances are derived from them. Under this account, atomistic space can approximate Euclidean space (and continuous space in general) very well. To motivate this account as a genuine solution to Weyl’s tile argument, I argue that this account is no less natural than the standard account of distance in continuous space. I also argue that the mixed account has distinctive advantages over Forrest’s (Synthese 103:327–354, 1995) account in response to Weyl’s tile argument, which can be considered as a restricted version of the mixed account.

 2020年1月8日 星期三 下午6:00 | Naoto Kura and Masahito Ueda | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Author(s): Naoto Kura and Masahito Ueda

Unlike well-established parameter estimation, function estimation faces conceptual and mathematical difficulties despite its enormous potential utility. We establish the fundamental error bounds on function estimation in quantum metrology for a spatially varying phase operator, where various degrees…

[Phys. Rev. Lett. 124, 010507] Published Wed Jan 08, 2020

 2020年1月8日 星期三 下午6:00 | Raban Iten, Tony Metger, Henrik Wilming, Lídia del Rio, and Renato Renner | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Author(s): Raban Iten, Tony Metger, Henrik Wilming, Lídia del Rio, and Renato Renner

Researchers probe a machine-learning model as it solves physics problems in order to understand how such models “think.”

[Phys. Rev. Lett. 124, 010508] Published Wed Jan 08, 2020

 2020年1月8日 星期三 下午4:26 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Drummond, Brian (2019) Understanding quantum mechanics: a review and synthesis in precise language. Open Physics, 17 (1). pp. 390-437. ISSN (Online) 2391-5471
 2020年1月8日 星期三 下午4:20 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Gomez-Marin, Alex and Arnau, Juan (2019) When the part mirrors the whole: interactions beyond simple location. [Preprint]
 2020年1月8日 星期三 上午8:00 | Yun Li | Nature Physics – Issue – nature.com science feeds

Nature Physics, Published online: 08 January 2020; doi:10.1038/s41567-019-0779-y

From classical to quantum

 2020年1月7日 星期二 上午10:17 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Vervoort, Louis (2020) The hypothesis of “hidden variables” as a unifying principle in physics. [Preprint]
 2020年1月6日 星期一 下午6:00 | D. A. Ivanov, T. Yu. Ivanova, S. F. Caballero-Benitez, and I. B. Mekhov | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Author(s): D. A. Ivanov, T. Yu. Ivanova, S. F. Caballero-Benitez, and I. B. Mekhov

We show that applying feedback and weak measurements to a quantum system induces phase transitions beyond the dissipative ones. Feedback enables controlling essentially quantum properties of the transition, i.e., its critical exponent, as it is driven by the fundamental quantum fluctuations due to m…

[Phys. Rev. Lett. 124, 010603] Published Mon Jan 06, 2020

 2020年1月5日 星期日 下午11:53 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Friederich, Simon (2019) A new fine-tuning argument for the multiverse. Foundations of Physics, 49. pp. 1011-1021. ISSN 0015-9018
 2020年1月5日 星期日 下午11:52 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Friederich, Simon (2019) Fine-Tuning as old evidence, double-counting, and the multiverse. International Studies in the Philosophy of Science, 31. pp. 363-377. ISSN 0269-8595
 2020年1月5日 星期日 下午11:51 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Friederich, Simon (2018) Reconsidering the inverse gambler’s fallacy charge against the fine-tuning argument for the multiverse. Journal for General Philosophy of Science, 50. pp. 29-41. ISSN 0925-4560
 2020年1月5日 星期日 下午11:24 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Friederich, Simon (2018) The asymptotic safety scenario for quantum gravity—an appraisal. Studies in History and Philosophy of Modern Physics, 63. pp. 65-73. ISSN 1355-2198
 2020年1月5日 星期日 下午11:22 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Dawid, Richard and Friederich, Simon (2019) Epistemic separability and Everettian branches—a critique of Sebens and Carroll. [Preprint]
 2020年1月5日 星期日 下午11:21 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
de Ronde, Christian (2020) The (Quantum) Measurement Problem in Classical Mechanics. [Preprint]