Weekly Papers on Quantum Foundations (37)

Underground test of gravity-related wave function collapse

2020年9月7日星期一上午8:00

Angelo Bassi

Nature Physics – Issue – nature.com science feeds

Nature Physics, Published online: 07 September 2020; doi:10.1038/s41567-020-1008-4The radiation emission rate from gravity-related wave function collapse is calculated and the results of a dedicated experiment at the Gran Sasso laboratory are reported, ruling out the natural parameter-free version of the Diósi–Penrose model.

A Local-Realistic Quantum Mechanical Model of Spin and Spin Entanglement. (arXiv:1901.00369v5 [quant-ph] UPDATED)

上午10:17

Antonio Sciarretta

quant-ph updates on arXiv.org

This paper aims at reproducing quantum mechanical (QM) spin and spin entanglement results using a realist, stochastic, and local approach, without the standard QM mathematical formulation. The concrete model proposed includes the description of Stern-Gerlach apparatuses and of Bell test experiments. Single particle trajectories are explicitly evaluated as a function of a few stochastic variables that they assumedly carry on. QM predictions re retrieved as probability distributions of similarly-prepared ensembles of particles. Notably, it is shown that the proposed model, despite being both local and realist, is able to violate the Bell–CHSH inequalities by exploiting the coincidence loophole and thus intrinsically renouncing to one of the Bell’s assumptions.Leggett-Garg tests for macrorealism: interference experiments and the simple harmonic oscillator. (arXiv:2009.03856v2 [quant-ph] UPDATED)

上午10:17

J.J.Halliwell, A.Bhatnagar, E.Ireland, H.Nadeem, V.Wimalaweera

quant-ph updates on arXiv.org

Leggett-Garg (LG) tests for macrorealism were originally designed to explore quantum coherence on the macroscopic scale. Interference experiments and systems modelled by harmonic oscillators provide useful examples of situations in which macroscopicity has been approached experimentally and may be turned into LG tests with a dichotomic variable Q by simple partitionings of a continuous variable such as position. Applying this approach to the double-slit experiment in which a measurement at the slits and screen are considered, we find that LG violations are always accompanied by destructive interference. The converse is not true in general and we find that there are non-trivial regimes in which there is destructive interference but the two-time LG inequalities are satisfied which implies that it is in fact often possible to assign (indirectly determined) probabilities for the interferometer paths. Similar features have been observed in recent work involving a LG analysis of a Mach-Zehnder interferometer and we compare with those results. We also compare with the related problem in which a more direct determination of the paths is carried out using a variable-strength measurement at the slits and the resulting deterioration of the interference pattern is examined. We extend the analysis to the triple-slit experiment. We find examples of some surprising relationships between LG inequalities and NSIT conditions that do not exist for dichotomic variables, including a violation of the Luders bound. We analyse a two-time LG inequality for the simple harmonic oscillator. We find an analytically tractable example showing a two-time LG violation with a gaussian initial state, echoing recent results of Bose et al (Phys. Rev. Lett. 120, 210402 (2018)).The Beginning of the Nuclear Age. (arXiv:2009.05001v1 [physics.hist-ph])

上午10:17

physics.hist-ph updates on arXiv.org

Authors: M. Shifman

The article below is based on lectures delivered to new students remotely in the course of orientation. It presents the quantum theory tree from its inception a century ago till today. The main focus is on the nuclear physics – HEP branch.The philosophical underpinning of the absorber theory of radiation

上午10:17

ScienceDirect Publication: Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern PhysicsScienceDirect RSShttps://www.sciencedirect.com/journal/studies-in-history-and-philosophy-of-science-part-b-studies-in-history-and-philosophy-of-modern-physicsRSS for NodeWed, 24 Jul 2019 09:46:42 GMTCopyright © 2019 Elsevier Ltd. All rights reservedImprints of the underlying structure of physical theoriesPublication date: Available online 12 July 2019Source: Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern PhysicsAuthor(s): Jorge ManeroAbstractIn the context of scientific realism, this paper intends to provide a formal and accurate description of the structural-based ontology posited by classical mechanics, quantum mechanics and special relativity, which is preserved across the empirical domains of these theories and explain their successful predictions. Along the lines of ontic structural realism, such a description is undertaken by

Publication date: Available online 9 September 2020

Source: Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics

Author(s): Marco ForgioneJump ship, shift gears, or just keep on chugging: Assessing the responses to tensions between theory and evidence in contemporary cosmology

上午10:17

Publication date: Available online 8 September 2020

Source: Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics

Author(s): Siska De Baerdemaeker, Nora Mills BoydJosephson AC effect induced by weak gravitational field. (arXiv:2009.04967v1 [gr-qc])

上午10:17

gr-qc updates on arXiv.org

Authors: Giovanni Alberto Ummarino, Antonio Gallerati

In this paper we examine the possibility of a Josephson AC effect between two superconductors induced by the Earth’s gravitational field, making use of the gravito-Maxwell formalism. The theoretical framework exploits the symmetry between the weak field expansion of the gravitational field and the standard Maxwell formulation, combined with the Josephson junction physics. We also suggest a suitable experimental setup, analysing also the related possible difficulties in measurements.Quantum entanglement and the non-orientability of spacetime. (arXiv:2009.04990v1 [hep-th])

上午10:17

gr-qc updates on arXiv.org

Authors: Ovidiu Racorean

We argue, in the context of Ads/CFT correspondence, that the degree of entanglement on the CFTs side determines the orientation of space and time on the dual global spacetime. That is, the global spacetime dual to entangled copies of field theory is non-orientable, while the product state of the CFTs results in an orientable spacetime. As a result, disentangling the degrees of freedom between two copies of CFT implies, on the gravity side, the transition from a non-orientable spacetime to a spacetime having a definite orientation of space and time, thus an orientable spacetime. We conclude showing that topology change induced by decreasing the entanglement between two sets of degrees of freedom corresponds to a topological blow down operation.The End of a Black Hole’s Evaporation — Part I. (arXiv:2009.05016v1 [gr-qc])

上午10:17

gr-qc updates on arXiv.org

Authors: Fabio D’Ambrosio, Marios Christodoulou, Pierre Martin-Dussaud, Carlo Rovelli, Farshid Soltani

At the end of Hawking evaporation, the horizon of a black hole enters a physical region where quantum gravity cannot be neglected. The physics of this region has not been much explored. We characterise its physics and introduce a technique to study it.Generalized uncertainty principle in resonant detectors of gravitational waves. (arXiv:2005.09454v2 [gr-qc] UPDATED)

上午10:17

gr-qc updates on arXiv.org

Authors: Sukanta Bhattacharyya, Sunandan Gangopadhyay, Anirban Saha

With the direct detection of gravitational waves by advanced LIGO detector, a new “window” to quantum gravity phenomenology has been opened. At present, these detectors achieve the sensitivity to detect the length variation ($\delta L$), $\mathcal{O} \approx 10^{-17}-10^{-21}$ meter. Recently a more stringent upperbound on the dimensionless parameter $\beta_0$, bearing the effect of generalized uncertainty principle has been given which corresponds to the intermediate length scale $l_{im}= \sqrt{\beta_0} l_{pl} \sim 10^{-23} m$. Hence the flavour of the generalized uncertainty principle can be realised by observing the response of the vibrations of phonon modes in such resonant detectors in the near future. In this paper, therefore, we calculate the resonant frequencies and transition rates induced by the incoming gravitational waves on these detectors in the generalized uncertainty principle framework. It is observed that the effects of the generalized uncertainty principle bears its signature in both the time independent and dependent part of the gravitational wave-harmonic oscillator Hamiltonian. We also make an upper bound estimate of the GUP parameter.What Have Google’s Random Quantum Circuit Simulation Experiments Demonstrated about Quantum Supremacy?

上午2:26