Weekly Papers on Quantum Foundations (49)

上午9:42 | Yiheng Lin, David R. Leibrandt, Dietrich Leibfried, Chin-wen Chou | quant-ph updates on arXiv.org

Conventional information processors freely convert information between different physical carriers to process, store, or transmit information. It seems plausible that quantum information will be carried by different physical carriers as well when developing systems for applications such as tests of fundamental physics, quantum-enhanced sensors, and quantum information processing. Quantum-controlled molecules in particular could transduce quantum information across a wide range of quantum-bit (qubit) frequencies, from a few kHz for transitions within the same rotational manifold, a few GHz for hyperfine transitions, up to a few THz for rotational transitions, to hundreds of THz for fundamental and overtone vibrational and electronic transitions, possibly all within the same molecule. Here, we report the first demonstration of entanglement between states of the rotation of a $\rm^{40}CaH^+$ molecular ion and internal states of a $\rm^{40}Ca^+$ atomic ion. The qubit addressed in the molecule has a frequency of either 13.4 kHz or 855 GHz, highlighting the versatility of molecular qubits. This work demonstrates how molecules can transduce quantum information between qubits with different frequencies to enable hybrid quantum systems. We anticipate that quantum control and measurement of molecules as demonstrated here will create opportunities for quantum information science, quantum sensors, fundamental and applied physics, and controlled quantum chemistry.

上午9:42 | Alexey A. Kryukov | quant-ph updates on arXiv.org

Newtonian and Schroedinger dynamics can be formulated in a physically meaningful way within the same Hilbert space framework. This fact was recently used to discover an unexpected relation between classical and quantum motions that goes beyond the results provided by the Ehrenfest theorem. The Newtonian dynamics was shown to be the Schroedinger dynamics of states constrained to a submanifold of the space of states, identified with the classical phase space of the system. Quantum observables are identified with vector fields on the space of states. The commutators of observables are expressed through the curvature of the space. The resulting embedding of the Newtonian and Schroedinger dynamics into a unified geometric framework is rigid in the sense that the Schroedinger dynamics is a unique extension of the Newtonian one. Furthermore, under the embedding, the normal distribution of measurement results associated with a classical measurement implies the Born rule for the probability of transition of quantum states. In this paper, the implications of the obtained theory to the process of measurement in quantum theory are analyzed. The double-slit, EPR and Schroedinger cat type experiments are reviewed anew. It is shown that, despite reproducing the usual results of quantum theory, the framework is not simply a reformulation of the theory. New experiments to discover the predicted effects are proposed.

上午9:42 | Cristian S. Calude, Elena Calude | quant-ph updates on arXiv.org

We present an idiosyncratic view of the race for quantum computational supremacy. Google’s approach and IBM challenge are examined. An unexpected side-effect of the race is the significant progress in designing fast classical algorithms. Quantum supremacy, if achieved, won’t make classical computing obsolete.

Working within the framework of parity-time-symmetric quantum mechanics we look into the possibility of entanglement generation and demonstrate that the feature of non-violation of no-signaling principle may hold for the simplest non-trivial case of bipartite systems. Basically our arguments are based on the computation of the reduced density matrix of one party to justify that the entropy of the other does not change.

Authors: José P. S. Lemos

The eclipse of the Sun of 1919 was fundamental in the development of physics and earns a high place in the history of science. Several players took part in this adventure. The most important are Einstein, Dyson, Eddington, the Sun, the Moon, Sobral, and Principe. Einstein’s theory of gravitation, general relativity, had the prediction that the gravitational field of the Sun deflects an incoming light ray from a background star on its way to Earth. The calculation gave that the shift in the star’s position was 1.75 arcseconds for light rays passing at the Sun’s rim. So to test it definitely it was necessary to be in the right places on May 29, 1919, the day of the eclipse. That indeed happened, with a Royal Greenwich Observatory team composed of Crommelin and Davidson that went to Sobral, and that was led at a distance by the Astronomer Royal Frank Dyson, and with Eddington of Cambridge University that went to Principe with his assistant Cottingham. The adventure is fascinating, from the preparations, to the day of the eclipse, the data analysis, the results, and the history that has been made. It confirmed general relativity, and marked an epoch that helped in delineating science in the post eclipse era up to now and into the future. This year of 2019 we are celebrating this enormous breakthrough

上午9:42 | 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 12 December 2019

Source: Physics Reports

Author(s): Giorgio Arcadi, Abdelhak Djouadi, Martti Raidal

Abstract

We review scenarios in which the particles that account for the Dark Matter (DM) in the Universe interact only through their couplings with the Higgs sector of the theory, the so-called Higgs-portal models. In a first step, we use a general and model-independent approach in which the DM particles are singlets with spin 0,12 or 1, and assume a minimal Higgs sector with the presence of only the Standard Model (SM) Higgs particle observed at the LHC. In a second step, we discuss non-minimal scenarios in which the spin-12 DM particle is accompanied by additional lepton partners and consider several possibilities like sequential, singlet-doublet and vector-like leptons. In a third step, we examine the case in which it is the Higgs sector of the theory which is enlarged either by a singlet scalar or pseudoscalar field, an additional two Higgs doublet field or by both; in this case, the matter content is also extended in several ways. Finally, we investigate the case of supersymmetric extensions of the SM with neutralino DM, focusing on the possibility that the latter couples mainly to the neutral Higgs particles of the model which then serve as the main portals for DM phenomenology. In all these scenarios, we summarize and update the present constraints and future prospects from the collider physics perspective, namely from the determination of the SM Higgs properties at the LHC and the search for its invisible decays into DM, and the search for heavier Higgs bosons and the DM companion particles at high-energy colliders. We then compare these results with the constraints and prospects obtained from the cosmological relic abundance as well as from direct and indirect DM searches in astroparticle physics experiments. The complementarity between collider and astroparticle searches is investigated in all considered models.

上午9:42 | 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 11 December 2019

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

Author(s): Sebastian De Haro, Jeroen van Dongen, Manus Visser, Jeremy Butterfield

Abstract

The microscopic state counting of the extremal Reissner-Nordström black hole performed by Andrew Strominger and Cumrun Vafa in 1996 has proven to be a central result in string theory. Here, with a philosophical readership in mind, the argument is presented in its contemporary context and its rather complex conceptual structure is analysed. In particular, we will identify the various inter-theoretic relations, such as duality and linkage relations, on which it depends. We further aim to make clear why the argument was immediately recognised as a successful accounting for the entropy of this black hole and how it engendered subsequent work that intended to strengthen the string theoretic analysis of black holes. Its relation to the formulation of the AdS/CFT conjecture will be briefly discussed, and the familiar reinterpretation of the entropy calculation in the context of the AdS/CFT correspondence is given. Finally, we discuss the heuristic role that Strominger and Vafa’s microscopic account of black hole entropy played for the black hole information paradox. A companion paper analyses the ontology of the Strominger-Vafa black hole states, the question of emergence of the black hole from a collection of D-branes, and the role of the correspondence principle in the context of string theory black holes.

上午9:42 | 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 11 December 2019

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

Author(s): Jeroen van Dongen, Sebastian De Haro, Manus Visser, Jeremy Butterfield

Abstract

This is one of a pair of papers that give a historical-cum-philosophical analysis of the endeavour to understand black hole entropy as a statistical mechanical entropy obtained by counting string-theoretic microstates. Both papers focus on Andrew Strominger and Cumrun Vafa’s ground-breaking 1996 calculation, which analysed the black hole in terms of D-branes. The first paper gives a conceptual analysis of the Strominger-Vafa argument, and of several research efforts that it engendered. In this paper, we assess whether the black hole should be considered as emergent from the d-brane system, particularly in light of the role that duality plays in the argument. We further identify uses of the quantum-to-classical correspondence principle in string theory discussions of black holes, and compare these to the heuristics of earlier efforts in theory construction, in particular those of the old quantum theory.

2019年12月13日 星期五 下午6:00 | G. Condon, M. Rabault, B. Barrett, L. Chichet, R. Arguel, H. Eneriz-Imaz, D. Naik, A. Bertoldi, B. Battelier, P. Bouyer, and A. Landragin | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Author(s): G. Condon, M. Rabault, B. Barrett, L. Chichet, R. Arguel, H. Eneriz-Imaz, D. Naik, A. Bertoldi, B. Battelier, P. Bouyer, and A. Landragin

We report on the all-optical production of Bose-Einstein condensates in microgravity using a combination of grey molasses cooling, light-shift engineering and optical trapping in a painted potential. Forced evaporative cooling in a 3-m high Einstein elevator results in 4×104 condensed atoms every 13…

[Phys. Rev. Lett. 123, 240402] Published Fri Dec 13, 2019

2019年12月13日 星期五 上午1:15 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Brown, Harvey R. and Ben Porath, Gal (2020) Everettian probabilities, the Deutsch-Wallace theorem and the Principal Principle. Springer International Publishing.
2019年12月12日 星期四 下午1:31 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Crowther, Karen (2019) As Below, So Before: `Synchronic’ and `Diachronic’ Conceptions of Spacetime Emergence. [Preprint]
2019年12月12日 星期四 下午1:28 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
Viger, Christopher and Hoefer, Carl and Viger, Daniel (2019) The philosopher’s paradox: How to make a coherent decision in the Newcomb Problem. THEORIA. An International Journal for Theory, History and Foundations of Science, 34 (3). pp. 407-421. ISSN 2171-679X
2019年12月11日 星期三 下午8:56 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
ROVELLI, Carlo and Rovelli, Carlo and Rovelli, Carlo and Rovelli, Carlo (2019) Can we travel to the past? Irreversible physics along closed timelike curves. [Preprint]
2019年12月11日 星期三 下午8:42 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
LE BIHAN, Baptiste (2016) Super-Relationism: Combining Eliminativism about Objects and Relationism about Spacetime. Philosophical Studies, 173 (8). pp. 2151-2172. ISSN 0031-8116
2019年12月11日 星期三 下午8:41 | Philsci-Archive: No conditions. Results ordered -Date Deposited.
LE BIHAN, Baptiste (2019) From Spacetime to Space and Time: A Reply to Markosian. [Preprint]

Abstract

The present paper revisits the debate between realists about gravitational energy in GR (who opine that gravitational energy can be said to meaningfully exist in GR) and anti-realists/eliminativists (who deny this). I re-assess the arguments underpinning Hoefer’s seminal eliminativist stance, and those of their realist detractors’ responses. A more circumspect reading of the former is proffered that discloses where the so far not fully appreciated, real challenges lie for realism about gravitational energy. I subsequently turn to Lam and Read’s recent proposals for such a realism. Their arguments are critically examined. Special attention is devoted to the adequacy of Read’s appeals to functionalism, imported from the philosophy of mind.

2019年12月9日 星期一 上午8:00 | Latest Results for Foundations of Physics

Abstract

We consider a stochastic process which is (a) described by a continuous-time Markov chain on only short time-scales and (b) constrained to conserve a number of hidden quantities on long time-scales. We assume that the transition matrix of the Markov chain is given and the conserved quantities are known to exist, but not explicitly given. To study the stochastic dynamics we propose to use the principle of stationary entropy production. Then the problem can be transformed into a variational problem for a suitably defined “action” and with time-dependent Lagrange multipliers. We show that the stochastic dynamics can be described by a Schrödinger equation, with Lagrange multipliers playing the role of phases, whenever (a) the transition matrix is symmetric or the detailed balance condition is satisfied, (b) the system is not too far from the equilibrium and (c) the number of the conserved quantities is large.

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