Testing quantum theory with thought experiments. (arXiv:2106.05314v1 [quant-ph])

上午9:49 | | | Nuriya Nurgalieva, Renato Renner | | | quant-ph updates on arXiv.org |

Quantum mechanics is one of our most successful physical theories; its predictions agree with experimental observations to an extremely high accuracy. However, the bare formalism of quantum theory does not provide straightforward answers to seemingly simple questions: for example, how should one model systems that include agents who are themselves using quantum theory? These foundational questions may be investigated with a theorist’s tool — the thought experiment. Its purpose is to turn debates about the interpretation of quantum theory into actual physics questions. In this article, we give a state-of-the-art overview on quantum thought experiments involving observers, from the basic Wigner’s friend to the recent Frauchiger-Renner setup, clarifying their interpretational significance and responding to objections and criticism on the way.

上午9:49 | | | Giulio Gasbarri, Alessio Belenchia, Matteo Carlesso, Sandro Donadi, Angelo Bassi, Rainer Kaltenbaek, Mauro Paternostro, Hendrik Ulbricht | | | quant-ph updates on arXiv.org |

Quantum technologies are opening novel avenues for applied and fundamental science at an impressive pace. In this perspective article, we focus on the promises coming from the combination of quantum technologies and space science to test the very foundations of quantum physics and, possibly, new physics. In particular, we survey the field of mesoscopic superpositions of nanoparticles and the potential of interferometric and non-interferometric experiments in space for the investigation of the superposition principle of quantum mechanics and the quantum-to-classical transition. We delve into the possibilities offered by the state-of-the-art of nanoparticle physics projected in the space environment and discuss the numerous challenges, and the corresponding potential advancements, that the space environment presents. In doing this, we also offer an ab-initio estimate of the potential of space-based interferometry with some of the largest systems ever considered and show that there is room for tests of quantum mechanics at an unprecedented level of detail.

Bohmian Zitterbewegung. (arXiv:2106.05827v1 [quant-ph])

上午9:49 | | | Giuseppe Raguni | | | quant-ph updates on arXiv.org |

A new bohmian quantum-relativistic model, in which arises a generalization of the classic Zitterbewegung discovered by Schr\”odinger, is proposed. It is obtained by introducing a new independent time parameter, whose relative motions are not directly observable but cause the uncertainties of the quantum observables. Unlike Bohm’s original theory, the quantum potential does not affect the observable motion, as for a normal external potential, but it only determines that one relative to the new time variable, of which the Zitterbewegung of a free particle is an example. The model also involves a relativistic revision of the uncertainty principle for particles with non-zero rest mass.

上午9:49 | | | Ricardo Gallego Torromé | | | quant-ph updates on arXiv.org |

Quantum systems are viewed as emergent systems from the fundamental degrees of freedom. The laws and rules of quantum mechanics are understood as an effective description, valid for the emergent systems and specially useful to handle probabilistic predictions of observables. After introducing the geometric theory of Hamilton-Randers spaces and reformulating it using Hilbert space theory, a Hilbert space structure is constructed from the Hilbert space formulation of the underlying Hamilton-Randers model and associated with the space of wave functions of quantum mechanical systems. We can prove the emergence of the Born rule from ergodic considerations. A geometric mechanism for a natural spontaneous collapse of the quantum states based on the concentration of measure phenomena as it appears in metric geometry is discussed.We show the existence of stable vacua states for the quantized matter Hamiltonian. Another consequence of the concentration of measure is the emergence of a weak equivalence principle for one of the dynamics of the fundamental degrees of freedom. We suggest that the reduction of the quantum state is driven by a gravitational type interaction.

Such interaction appears only in the dynamical domain when localization of quantum observables happens, it must be a classical interaction. We discuss the double slit experiment in the context of the framework proposed, the interference phenomena associated with a quantum system in an external gravitational potential, a mechanism explaining non-quantum locality and also provide an argument in favour of an emergent interpretation of every macroscopic time parameter. Entanglement is partially described in the context of Hamilton-Randers theory and how naturally Bell’s inequalities should be violated.

上午9:49 | | | Thomas D. Galley, Flaminia Giacomini, John H. Selby | | | quant-ph updates on arXiv.org |

Recently, table-top experiments involving massive quantum systems have been proposed to test the interface of quantum theory and gravity. In particular, the crucial point of the debate is whether it is possible to conclude anything on the quantum nature of the gravitational field, provided that two quantum systems become entangled due to solely the gravitational interaction. Typically, this question has been addressed by assuming an underlying physical theory to describe the gravitational interaction, but no systematic approach to characterise the set of possible gravitational theories which are compatible with the observation of entanglement has been proposed. Here, we introduce the framework of Generalised Probabilistic Theories (GPTs) to the study of the nature of the gravitational field. This framework has the advantage that it only relies on the set of operationally accessible states, transformations, and measurements, without presupposing an underlying theory. Hence, it provides a framework to systematically study all theories compatible with the detection of entanglement generated via the gravitational interaction between two non-classical systems. Assuming that such entanglement is observed we prove a no-go theorem stating that the following statements are incompatible: i) the two non-classical systems are independent subsystems, ii) the gravitational field is a physical degree of freedom which mediates the interaction and iii) the gravitational field is classical. Moreover we argue that conditions i) and ii) should be met, and hence that the gravitational field is non-classical. Non-classicality does not imply that the gravitational field is quantum, and to illustrate this we provide examples of non-classical and non-quantum theories which are logically consistent with the other conditions.

Causality and gravity. (arXiv:2106.05912v1 [hep-th])

上午9:49 | | | gr-qc updates on arXiv.org |

Authors: John F. Donoghue, Gabriel Menezes

We show how uncertainty in the causal structure of field theory is essentially inevitable when one includes quantum gravity. This includes the fact that lightcones are ill-defined in such a theory – independent of the UV completion of the theory. We include details of the causality uncertainty which arises in theories of quadratic gravity.

Testing the black-hole area law with GW150914. (arXiv:2012.04486v2 [gr-qc] UPDATED)

上午9:49 | | | gr-qc updates on arXiv.org |

Authors: Maximiliano Isi, Will M. Farr, Matthew Giesler, Mark A. Scheel, Saul A. Teukolsky

We present observational confirmation of Hawking’s black-hole area theorem based on data from GW150914, finding agreement with the prediction with 97% (95%) probability when we model the ringdown including (excluding) overtones of the quadrupolar mode. We obtain this result from a new time-domain analysis of the pre- and postmerger data. We also confirm that the inspiral and ringdown portions of the signal are consistent with the same remnant mass and spin, in agreement with general relativity.

A closer glance at black hole pair creation. (arXiv:2103.05782v2 [hep-th] UPDATED)

上午9:49 | | | gr-qc updates on arXiv.org |

Authors: Anrés Anabalón, Sasha Brenner, Gaston Giribet, Luciano Montecchio

We consider accelerated black hole horizons with and without defects. These horizons appear in the $C$-metric solution to Einstein equations and in its generalization to the case where external fields are present. These solutions realize a variety of physical processes, from the decay of a cosmic string by a black hole pair nucleation to the creation of a black hole pair by an external electromagnetic field. Here, we show that such geometries exhibit an infinite set of symmetries in their near horizon region, generalizing in this way previous results for smooth isolated horizons. By considering the limit close to both the black hole and the acceleration horizons, we show that a sensible set of asymptotic boundary conditions gets preserved by supertranslation and superrotation transformations. By acting on the geometry with such transformations, we derive the superrotated, supertranslated version of the $C$-metric and compute the associated conserved charges.

Black hole remnants are not too fast to be dark matter. (arXiv:2105.01627v2 [gr-qc] UPDATED)

上午9:49 | | | gr-qc updates on arXiv.org |

Authors: Benjamin V. Lehmann, Stefano Profumo

We comment on recent claims that recoil in the final stages of Hawking evaporation gives black hole remnants large velocities, rendering them inviable as a dark matter candidate. We point out that due to cosmic expansion, such large velocities at the final stages of evaporation are not in tension with the cold dark matter paradigm so long as they are attained at sufficiently early times. In particular, the predicted recoil velocities are robustly compatible with observations if the remnants form before the epoch of big bang nucleosynthesis, a requirement which is already imposed by the physics of nucleosynthesis itself.

Machines will think: structure and interpretation of Alan Turing’s imitation game

上午7:30 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gonçalves, Bernardo (2021) Machines will think: structure and interpretation of Alan Turing’s imitation game. The Digital Library of Theses and Dissertations of the University of São Paulo. pp. 1-291.

Relativistic Bell Test within Quantum Reference Frames

2021年6月11日 星期五 下午6:00 | | | Lucas F. Streiter, Flaminia Giacomini, and Časlav Brukner | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Lucas F. Streiter, Flaminia Giacomini, and Časlav Brukner

A still widely debated question in the field of relativistic quantum information is whether entanglement and the degree of violation of Bell’s inequalities for massive relativistic particles are frame independent or not. At the core of this question is the effect that spin gets entangled with the mo…

[Phys. Rev. Lett. 126, 230403] Published Fri Jun 11, 2021

Energy Requirements Undermine Substrate Independence and Mind-Body Functionalism

2021年6月10日 星期四 下午3:43 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Thagard, Paul (2021) Energy Requirements Undermine Substrate Independence and Mind-Body Functionalism. [Preprint]

2021年6月9日 星期三 上午8:00 | | | Romain Fleury | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 09 June 2021; doi:10.1038/s41567-021-01281-5

Introducing non-local effects to metamaterials increases the complexity of their dispersion relation, which allows carefully designed elastic structures to mimic the peculiar roton behaviour of correlated quantum superfluids.

Absolute Space as a Necessary Idea: Reading Kant’s Phenomenology through Perspectival Lenses

2021年6月8日 星期二 上午6:01 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Massimi, Michela (2021) Absolute Space as a Necessary Idea: Reading Kant’s Phenomenology through Perspectival Lenses. [Preprint]

“Reverse Engineering” the de Broglie Wave

2021年6月8日 星期二 上午5:57 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Shanahan, Daniel “Reverse Engineering” the de Broglie Wave. UNSPECIFIED.

A response to the Mucino-Okon-Sudarsky’s Assessment of Relational Quantum Mechanics

2021年6月8日 星期二 上午5:54 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

ROVELLI, Carlo (2021) A response to the Mucino-Okon-Sudarsky’s Assessment of Relational Quantum Mechanics. [Preprint]