Gravity entanglement, quantum reference systems, degrees of freedom. (arXiv:2207.03138v1 [quant-ph])

上午9:51 | | | Marios Christodoulou, Andrea Di Biagio, Richard Howl, Carlo Rovelli | | | quant-ph updates on arXiv.org |

We discuss the physical interpretation of the gravity mediated entanglement effect. We show how to read it in terms of quantum reference systems. We pinpoint the single gravitational degree of freedom mediating the entanglement. We clarify why the distinction between longitudinal and transverse degrees of freedom is irrelevant for the interpretation of the results. We discuss the relation between the LOCC theorem and the interpretation of the effect, its different relevance for, respectively, the quantum gravity and quantum information communities, and the reason for the excitement raised by the prospect of detection.

A model of Non-Relativistic Quantum Spacetime. (arXiv:2207.01005v2 [quant-ph] UPDATED)

上午9:51 | | | Tommaso Favalli, Augusto Smerzi | | | quant-ph updates on arXiv.org |

We consider a global quantum system (the “Universe”) satisfying a double constraint, both on total energy and total momentum. Generalizing the Page and Wootters quantum clock formalism, we provide a model of 3+1 dimensional, non-relativistic, quantum spacetime emerging from entanglement among different subsystems in a globally “timeless” and “positionless” Universe.

上午9:51 | | | physics.hist-ph updates on arXiv.org |

Authors: Zeki Can Seskir, Jacob Biamonte

We argue that quantum computing underwent an inflection point circa 2017. Long promised funding materialised which prompted public and private investments around the world. Techniques from machine learning suddenly influenced central aspects of the field. On one hand, machine learning was used to emulate quantum systems. On the other hand, quantum algorithms became viewed as a new type of machine learning model (creating the new model of {\it variational} quantum computation). Here we sketch some milestones which have lead to this inflection point. We argue that the next inflection point would occur around when practical problems will be first solved by quantum computers. We anticipate that by 2050 this would have become commonplace, were the world would still be adjusting to the possibilities brought by quantum computers.

The physics of heart rhythm disorders

上午9:51 | | | ScienceDirect Publication: Physics ReportsScienceDirect RSShttps://www.sciencedirect.com/journal/physics-reportsRSS for NodeTue, 23 Jul 2019 10:02:48 GMTCopyright © 2019 Elsevier B.V. All rights reservedRapid solidification as non-ergodic phenomenonPublication date: 20 July 2019Source: Physics Reports, Volume 818Author(s): P.K. Galenko, D. JouAbstractRapid solidification is a relevant physical phenomenon in material sciences, whose theoretical analysis requires going beyond the limits of local equilibrium statistical physics and thermodynamics and, in particular, taking account of ergodicity breaking and of generalized formulation of thermodynamics. The ergodicity breaking is related to the time symmetry breaking and to the presence of some kinds of fluxes and gradient flows making that an average of microscopic variables along time is different than an average over some chosen statistical ensemble. In fast processes, this is due, for instance, to the fact that the system has no time enough to explore the who |

Publication date: 19 September 2022

**Source:** Physics Reports, Volume 978

Author(s): Wouter-Jan Rappel

Corrigendum to “The landscape of QCD axion models” [Phys. Rep. 870 (2020) 1-117]

上午9:51 | | | ScienceDirect Publication: Physics ReportsScienceDirect RSShttps://www.sciencedirect.com/journal/physics-reportsRSS for NodeTue, 23 Jul 2019 10:02:48 GMTCopyright © 2019 Elsevier B.V. All rights reservedRapid solidification as non-ergodic phenomenonPublication date: 20 July 2019Source: Physics Reports, Volume 818Author(s): P.K. Galenko, D. JouAbstractRapid solidification is a relevant physical phenomenon in material sciences, whose theoretical analysis requires going beyond the limits of local equilibrium statistical physics and thermodynamics and, in particular, taking account of ergodicity breaking and of generalized formulation of thermodynamics. The ergodicity breaking is related to the time symmetry breaking and to the presence of some kinds of fluxes and gradient flows making that an average of microscopic variables along time is different than an average over some chosen statistical ensemble. In fast processes, this is due, for instance, to the fact that the system has no time enough to explore the who |

Publication date: Available online 7 July 2022

**Source:** Physics Reports

Author(s): Luca Di Luzio, Maurizio Giannotti, Enrico Nardi, Luca Visinelli

Observables In Cosmology: Three Astronomical Perspectives. (arXiv:2207.03296v1 [gr-qc])

上午9:51 | | | gr-qc updates on arXiv.org |

Authors: Jérémie Francfort

In this thesis, I present three projects I carried out during m PhD. In the first project, I introduce Conformal Transformations and the Galaxy Number County. I explicitly show that the Galaxy Number Counts is invariant under Conformal Transformations, which makes it a good physical observable. In the second project, I study how weak lensing, and in particular cosmic shear, affects the shape of the galaxy images. I show that, if the light polarisation is also measured, the rotation of the main axes of the elliptical galaxy shape becomes a cosmological observable. I show how this can be used to estimate cosmic shear and its correlation functions. In the third project, I define a higher order (Riemann-squared and -cubed) Lagrangian Effective Theory of Gravity. I compute the linear correction to the speed and the quasinormal frequencies of the gravitational waves in this theory around a Schwarzschild-like background.

Non-commutative Geometry from Perturbative Quantum Gravity. (arXiv:2207.03345v1 [gr-qc])

上午9:51 | | | gr-qc updates on arXiv.org |

Authors: Markus Fröb, Albert Much, Kyriakos Papadopoulos

Trying to connect a fundamentally non-commutative spacetime with the conservative perturbative approach to quantum gravity, we are led to the natural question: are non-commutative geometrical effects already present in the regime where perturbative quantum gravity provides a predictive framework? Moreover, is it necessary to introduce non-commutativity by hand, or does it arise through quantum-gravitational effects? We show that the first question can be answered in the affirmative, and the second one in the negative: perturbative quantum gravity predicts non-commutativity at the Planck scale, once one clarifies the structure of observables in the quantum theory.

A Dynamical Perspective on the Arrow of Time

2022年7月8日 星期五 下午4:14 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Salimkhani, Kian (2022) A Dynamical Perspective on the Arrow of Time. [Preprint]

Two Forms of Functional Reductionism in Physics

2022年7月8日 星期五 下午4:14 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Lorenzetti, Lorenzo (2022) Two Forms of Functional Reductionism in Physics. [Preprint]

The open past in an indeterministic physics

2022年7月8日 星期五 下午4:11 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Del Santo, Flavio and Gisin, Nicolas (2022) The open past in an indeterministic physics. [Preprint]

Theoretical Virtues and Theorizing in Physics: Against the Instrumentalist View of Simplicity

2022年7月8日 星期五 下午4:11 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Mohammadian, Mousa (2021) Theoretical Virtues and Theorizing in Physics: Against the Instrumentalist View of Simplicity. Synthese, 199 (1). pp. 4819-4828. ISSN 1573-0964

Securing the Objectivity of Relative Facts in the Quantum World

2022年7月6日 星期三 下午4:08 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Healey, Richard (2022) Securing the Objectivity of Relative Facts in the Quantum World. [Preprint]

2022年7月5日 星期二 下午6:00 | | | Naoto Shiraishi | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Naoto Shiraishi

We propose a time-symmetric counterpart of the current in stochastic thermodynamics named the time-symmetric current. This quantity is defined with empirical measures and thus is symmetric under time reversal, while its ensemble average reproduces the amount of the average current. We prove that thi…

[Phys. Rev. Lett. 129, 020602] Published Tue Jul 05, 2022

Mysteries of Actual Causation: It’s Complicated

2022年7月5日 星期二 下午4:08 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Woodward, James (2022) Mysteries of Actual Causation: It’s Complicated. [Preprint]

A new EPR-Bohm experiment with reversible measurements

2022年7月5日 星期二 下午4:06 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gao, Shan (2022) A new EPR-Bohm experiment with reversible measurements. [Preprint]

Meaning in time: on temporal externalism and Kripkenstein’s skeptical challenge

2022年7月5日 星期二 上午8:00 | | | Latest Results for Synthese |

**Abstract**

The main question of metasemantics, or foundational semantics, is why an expression token has the meaning (semantic value) that it in fact has. In his reading of Ludwig Wittgenstein’s later work, Saul Kripke presented a skeptical challenge that threatened to make the foundational question unanswerable. My first contention in this paper is that the skeptical challenge indeed poses an insoluble paradox, but only for a certain kind of metasemantic theory, against which the challenge effectively works as a reductio ad absurdum argument. My second contention is that as a result of rejecting the theory which entails a paradoxical outcome, we will see that the foundational question essentially involves a temporal dimension. After arguing that the skeptical challenge gives us a strong reason to adopt a historical view of meaning, I shall further argue against certain authors who claim that meanings not only have histories but futures as well, or that the meaning of a word may change retroactively in time as a consequence of counterfactual change in its future use. The major aim of the paper is thus to bring together the arguably interrelated debates about the skeptical challenge and temporal externalism in philosophy of language.

Superconducting quantum interference at the atomic scale

2022年7月4日 星期一 上午8:00 | | | Christian R. Ast | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 04 July 2022; doi:10.1038/s41567-022-01644-6

Continuously changing the coupling between a magnetic impurity and a superconductor allows the observation of the reversal of supercurrent flow at the atomic scale.

Robustness and dark matter observation

2022年7月3日 星期日 下午3:51 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Antoniou, Antonis (2022) Robustness and dark matter observation. [Preprint]