# On a Quantum Theory of Relativity

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## Latest Results for International Journal of Theoretical Physics

on 2017-9-01 5:00am GMT

### Abstract

As expressed in terms of classical coordinates, the inertial spacetime metric that contains quantum corrections deriving from a quantum potential defined from the quantum probability amplitude is obtained to be given as an elliptic integral of the second kind that does not satisfy Lorentz transformations but a generalised invariance quantum group. Based on this result, we introduce a new, alternative procedure to quantise Einstein general relativity where the metric is also given in terms of elliptic integrals and is free from the customary problems of the current quantum models. We apply the procedure to Schwarzschild black holes and briefly analyse the results.

# No smooth beginning for spacetime. (arXiv:1705.00192v2 [hep-th] UPDATED)

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on 2017-8-19 8:40am GMT

Authors: Job Feldbrugge, Jean-Luc Lehners, Neil Turok

We identify a fundamental obstruction to any theory of the beginning of the universe, formulated as a semiclassical path integral. Hartle and Hawking's no boundary proposal and Vilenkin's tunneling proposal are examples of such theories. Each may be formulated as the quantum amplitude for obtaining a final 3-geometry by integrating over 4-geometries. We introduce a new mathematical tool - Picard-Lefschetz theory - for defining the semiclassical path integral for gravity. The Lorentzian path integral for quantum cosmology with a positive cosmological constant is meaningful in this approach, but the Euclidean version is not. Framed in this way, the resulting framework and predictions are unique. Unfortunately, the outcome is that primordial tensor (gravitational wave) fluctuations are unsuppressed. We prove a general theorem to this effect, in a wide class of theories.

# Are black holes about information?

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## Philsci-Archive: No conditions. Results ordered -Date Deposited.

on 2017-8-18 8:02pm GMT
Wuthrich, Christian (2017) Are black holes about information? [Preprint]

# The Algebra of the Pseudo-Observables II: The Measurement Problem. (arXiv:1708.01170v1 [quant-ph] CROSS LISTED)

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on 2017-8-18 9:17am GMT

Authors: Edoardo Piparo

In this second paper, we develop the full mathematical structure of the algebra of the pseudo-observables, in order to solve the quantum measurement problem. Quantum state vectors are recovered but as auxiliary pseudo-observables storing the information acquired in a set of observations. The whole process of measurement is deeply reanalyzed in the conclusive section, evidencing original aspects. The relation of the theory with some popular interpretations of Quantum Mechanics is also discussed, showing that both Relational Quantum Mechanics and Quantum Bayesianism may be regarded as compatible interpretations of the theory. A final discussion on reality, tries to bring a new insight on it.

# The Algebra of the Pseudo-Observables I: Why Quantum Mechanics is the ultimate description of Reality. (arXiv:1707.05633v3 [quant-ph] CROSS LISTED)

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on 2017-8-18 9:17am GMT

Authors: Edoardo Piparo (Ministero dell'Istruzione dell'Università e della Ricerca)

This paper is the first of several parts introducing a new powerful algebra: the algebra of the pseudo-observables. This is a C*-algebra whose set is formed by formal expressions involving observables. The algebra is constructed by applying the Occam's razor principle, in order to obtain the minimal description of physical reality. Proceeding in such a manner, every aspect of quantum mechanics acquires a clear physical interpretation or a logical explanation, providing, for instance, in a natural way the reason for the structure of complex algebra and the matrix structure of Werner Heisenberg's formulation of quantum mechanics. Last but not least, the very general hypotheses assumed, allow one to state that quantum mechanics is the unique minimal description of physical reality.

# No Rescue for the No Boundary Proposal. (arXiv:1708.05104v1 [hep-th])

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on 2017-8-18 4:30am GMT

Authors: Job Feldbrugge, Jean-Luc Lehners, Neil Turok

In recent work, we introduced Picard-Lefschetz theory as a tool for defining the Lorentzian path integral for quantum gravity in a systematic semiclassical expansion. This formulation avoids several pitfalls occurring in the Euclidean approach. Our method provides, in particular, a more precise formulation of the Hartle-Hawking no boundary proposal, as a sum over real Lorentzian four-geometries interpolating between an initial three-geometry of zero size, {\it i.e}, a point, and a final three-geometry. With this definition, we calculated the no boundary amplitude for a closed universe with a cosmological constant, assuming cosmological symmetry for the background and including linear perturbations. We found the opposite semiclassical exponent to that obtained by Hartle and Hawking for the creation of a de Sitter spacetime "from nothing". Furthermore, we found the linearized perturbations to be governed by an {\it inverse} Gaussian distribution, meaning they are unsuppressed and out of control. Recently, Diaz Dorronsoro {\it et al.} followed our methods but attempted to rescue the no boundary proposal by integrating the lapse over a different, intrinsically complex contour. Here, we show that, in addition to the desired Hartle-Hawking saddle point contribution, their contour yields extra, non-perturbative corrections which again render the perturbations unsuppressed. We prove there is {\it no} choice of complex contour for the lapse which avoids this problem. We extend our discussion to include backreaction in the leading semiclassical approximation, fully nonlinearly for the lowest tensor harmonic and to second order for all higher modes. Implications for quantum de Sitter spacetime and for cosmic inflation are briefly discussed.

# On the thermodynamic implications of path integral formalism of quantum mechanics. (arXiv:1708.05113v1 [cond-mat.stat-mech])

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on 2017-8-18 4:25am GMT

Authors: Ken Funo, H. T. Quan

By introducing novel concepts of work and heat functionals along individual $"$path$"$, we reformulate quantum Jarzynski equality based on the path integral formulation of quantum mechanics. When applied to an open quantum system described by the quantum Brownian motion model, we establish a consistent framework of quantum thermodynamics in the strong coupling regime. Using the work and heat functionals, we derive a path-integral expression for the work and heat statistics. This formalism provides an effective way to calculate the work and heat in open quantum systems by utilizing various path integral techniques. By performing the $\hbar$ expansion, we analytically prove the quantum-classical correspondence of the work and heat statistics. In addition, we obtain the $n$-th order quantum correction to the classical work.

# Complementarity, wave-particle duality, and domains of applicability

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## ScienceDirect Publication: Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics

on 2017-8-17 5:03pm GMT
Publication date: Available online 14 August 2017
Source:Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics
Author(s): Peter Bokulich
Complementarity has frequently, but mistakenly, been conflated with wave-particle duality, and this conflation has led to pervasive misunderstandings of Bohr's views and several misguided claims of an experimental “disproof” of complementarity. In this paper, I explain what Bohr meant by complementarity, and how this is related to, but distinct from, wave-particle duality. I list a variety of possible meanings of wave-particle duality, and canvass the ways in which they are (or are not) supported by quantum physics and Bohr's interpretation. I also examine the extent to which wave-particle duality should be viewed as an example of the sort of dualities one finds in, e.g., string theory. I argue that the most fruitful way of reading of Bohr's account complementarity is by comparing it to current accounts of effective theories with limited domains of applicability.

# Analysis of the Jun Ishiwara's "The universal meaning of the quantum of action". (arXiv:1708.04676v1 [physics.hist-ph])

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on 2017-8-17 1:04am GMT

Authors: Karla Pelogia, Carlos Alexandre Brasil

Here we present an analysis of the paper "Universelle Bedeutung des Wirkungsquantums" (The universal meaning of the quantum of action), published by Jun Ishiwara in German in the "Proceedings of Tokyo Mathematico-Physical Society 8 (1915) 106-116". In his work, Ishiwara, established in the Sendai University, Japan, proposed - simultaneously with Arnold Sommerfeld, William Wilson and Niels Bohr in Europe - the phase-space-integral quantization, a rule that would be incorporated into the old-quantum-theory formalism. The discussions and analysis render this paper fully accessible to undergraduate students of physics with elementary knowledge of quantum mechanics.

# Non-interferometric test of the Continuous Spontaneous Localization model based on the torsional motion of a cylinder. (arXiv:1708.04812v1 [quant-ph])

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on 2017-8-17 1:04am GMT

The Continuous Spontaneous Localization (CSL) model is the best known and studied among collapse models, which modify quantum mechanics and identify the fundamental reasons behind the unobservability of quantum superpositions at the macroscopic scale. Albeit several tests were performed during the last decade, up to date the CSL parameter space still exhibits a vast unexplored region. Here, we study and propose an unattempted non-interferometric test aimed to fill this gap. We show that the angular momentum diffusion predicted by CSL heavily constrains the parametric values of the model when applied to a macroscopic cylinder, eventually allowing to cover the unexplored region of the parameter space.

# Quantum bit commitment and the reality of the quantum state. (arXiv:1708.04964v1 [quant-ph])

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on 2017-8-17 1:04am GMT

Authors: R. Srikanth

Quantum bit commitment (QBC) is insecure in the standard non-relativistic quantum cryptographic framework, essentially because Alice can exploit quantum steering to defer making her commitment. Two assumptions implicit in this framework are that: (a) the same system $E$ would be used for submitting the evidence for either commitment (That is, only the commitment-encoding states are different-- but not the submitted system itself-- for different commitments); and (b) system $E$ is quantum rather than classical. Here, we show how relaxing assumption (a) or (b) can render her malicious steering operation indeterminable or inexistent, respectively. Finally, we present a secure protocol that relaxes both assumptions in a quantum teleportation setting. Without appeal to an ontological framework, we argue that the protocol's security entails the reality of the quantum state, provided retrocausality is excluded.

# From statistical proofs of the Kochen-Specker theorem to noise-robust noncontextuality inequalities. (arXiv:1708.04793v1 [quant-ph])

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on 2017-8-17 1:04am GMT

Authors: Ravi Kunjwal, Robert W. Spekkens

The Kochen-Specker theorem rules out models of quantum theory wherein sharp measurements are assigned outcomes deterministically and independently of context. This notion of noncontextuality is not applicable to experimental measurements because these are never free of noise and thus never truly sharp. For unsharp measurements, therefore, one must drop the requirement that an outcome is assigned deterministically in the model and merely require that the distribution over outcomes that is assigned in the model is context-independent. By demanding context-independence in the representation of preparations as well, one obtains a generalized principle of noncontextuality that also supports a quantum no-go theorem. Several recent works have shown how to derive inequalities on experimental data which, if violated, demonstrate the impossibility of finding a generalized-noncontextual model of this data. That is, these inequalities do not presume quantum theory and, in particular, they make sense without requiring a notion of "sharpness" of measurements in any operational theory describing the experiment. We here describe a technique for deriving such inequalities starting from arbitrary proofs of the Kochen-Specker theorem. It extends significantly previous techniques, which worked only for logical proofs (based on uncolourable orthogonality graphs), to the case of statistical proofs (where the graphs are colourable, but the colourings cannot explain the quantum statistics). The derived inequalities are robust to noise.

# Analysis of the Jun Ishiwara's "The universal meaning of the quantum of action". (arXiv:1708.04676v1 [physics.hist-ph])

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on 2017-8-17 1:04am GMT

Authors: Karla Pelogia, Carlos Alexandre Brasil

Here we present an analysis of the paper "Universelle Bedeutung des Wirkungsquantums" (The universal meaning of the quantum of action), published by Jun Ishiwara in German in the "Proceedings of Tokyo Mathematico-Physical Society 8 (1915) 106-116". In his work, Ishiwara, established in the Sendai University, Japan, proposed - simultaneously with Arnold Sommerfeld, William Wilson and Niels Bohr in Europe - the phase-space-integral quantization, a rule that would be incorporated into the old-quantum-theory formalism. The discussions and analysis render this paper fully accessible to undergraduate students of physics with elementary knowledge of quantum mechanics.

# Quantum mechanics with space-time noncommutativity. (arXiv:1708.04769v1 [quant-ph])

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on 2017-8-17 1:04am GMT

We construct an effective commutative Schr\"odinger equation in Moyal space-time in $(1+1)$-dimension where both $t$ and $x$ are operator-valued and satisfy $\left[ \hat{t}, \hat{x} \right] = i \theta$. Beginning with a time-reparametrised form of an action we identify the actions of various space-time coordinates and their conjugate momenta on quantum states, represented by Hilbert-Schmidt operators. Since time is also regarded as a configuration space variable, we show how an induced' inner product can be extracted, so that an appropriate quantum mechanical interpretation is obtained. We then discuss several other applications of the formalism developed so far.

# Conservation, Inertia, and Spacetime Geometry

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## Philsci-Archive: No conditions. Results ordered -Date Deposited.

on 2017-8-16 6:45pm GMT
Weatherall, James Owen (2017) Conservation, Inertia, and Spacetime Geometry. [Preprint]

# Notes on microstates, Tsallis statistics and entropic gravity formalism. (arXiv:1708.04596v1 [hep-th])

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on 2017-8-16 9:04am GMT

It is an old idea to realize Einstein's equations as a thermodynamical equation of state. Since then, there has been new conjectures to understand gravity from another point of view. In this way we can accept that the gravitational field is not an underlying one like an emergent force from other approaches based on the knowledge of relativity, quantum and black holes thermodynamics, and different statistical formalisms. One important question concerning this gravity/thermostatistics correspondence is whether the holographic screen could be well defined for a nonrelativistic case of a source mass. Hence, to understand the actual role of the holographic screen is a very relevant issue. In this letter we have analyzed the entropy as a function of the holographic screen in some different scenarios. We have disclosed modified Newtonian dynamics (MOND) from Verlinde's ideas. Besides, we have calculated some cosmological elements using the same ideas. The results obtained using MOND will guide us to obtain other cosmological results.

# A conjecture concerning determinism, reduction, and measurement in quantum mechanics. (arXiv:1204.0614v6 [quant-ph] UPDATED)

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on 2017-8-16 2:56am GMT

Authors: Arthur Jabs

Determinism is established in quantum mechanics by tracing the probabilities in the Born rules back to the absolute (overall) phase constants of the wave functions and recognizing these phase constants as pseudorandom numbers. The reduction process (collapse) is independent of measurement. It occurs when two wavepackets overlap in ordinary space and satisfy a certain criterion, which depends on the phase constants of both wavepackets. Reduction means contraction of the wavepackets to the place of overlap. A measurement apparatus always fans out the incoming wavepacket into spatially separated eigenpackets of the chosen observable. When one of these eigenpackets together with a wavepacket in the apparatus satisfy the criterion, the reduction associates the place of contraction with an eigenvalue of the observable. The theory is nonlocal and contextual.

# The Quantum Revolution in Philosophy

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## Physics

on 2017-8-15 12:00am GMT
Author: Richard Healey
ISBN: 9780198714057
Binding: Hardcover
Publication Date: 15 August 2017

# Time Symmetric Quantum Theory Without Retrocausality. (arXiv:1707.08641v1 [quant-ph])

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on 2017-7-28 2:25am GMT

Authors: Tim Maudlin

In their recent paper "Is a Time Symmetric Interpretation of Quantum Theory Possible Without Retrocausality?", Matthew Leifer and Matthew Pusey argue that the answer to their title question is "no". Unfortunately, the central proof offered in the paper contains a fatal error, and the conclusion cannot be established. Interpretations of quantum theory without retrocausalty can be time symmetric not only in the traditional sense but also in Leifer and Pusey's supposedly stricter sense. There appear to be no prospects for proving any analogous theorem.

# Curve-Fitting for Bayesians?

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## Philsci-Archive: No conditions. Results ordered -Date Deposited.

on 2017-7-27 8:03pm GMT
Belot, Gordon (2015) Curve-Fitting for Bayesians? [Preprint]

# The state of Hawking radiation is non-classical. (arXiv:1707.08427v1 [hep-th])

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on 2017-7-27 9:35am GMT

Authors: Ram Brustein, A.J.M. Medved, Yoav Zigdon

We show that the state of the Hawking radiation emitted from a large Schwarzschild black hole (BH) deviates significantly from a classical state, in spite of its apparent thermality. For this state, the occupation numbers of single modes of massless asymptotic fields, such as photons, gravitons and possibly neutrinos, are small and, as a result, their relative fluctuations are large. The occupation numbers of massive fields are much smaller and suppressed beyond even the expected Boltzmann suppression. It follows that this type of thermal state cannot be viewed as classical or even semiclassical. We substantiate this claim by showing that, in a state with low occupation numbers, physical observables have large quantum fluctuations and, as such, cannot be faithfully described by a mean-field or by a WKB-like semiclassical state. Since the evolution of the BH is unitary, our results imply that the state of the BH interior must also be non-classical when described in terms of the asymptotic fields. We show that such a non-classical interior cannot be described in terms of a semiclassical geometry, even though the average curvature is sub-Planckian.

# Fritz London and the scale of quantum mechanisms

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## ScienceDirect Publication: Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics

on 2017-7-27 8:47am GMT
Publication date: Available online 26 July 2017
Source:Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics
Author(s): Daniela Monaldi
Fritz London's seminal idea of “quantum mechanisms of macroscopic scale”, first articulated in 1946, was the unanticipated result of two decades of research, during which London pursued quantum-mechanical explanations of various kinds of systems of particles at different scales. He started at the microphysical scale with the hydrogen molecule, generalized his approach to chemical bonds and intermolecular forces, then turned to macrophysical systems like superconductors and superfluid helium. Along this path, he formulated a set of concepts—the quantum mechanism of exchange, the rigidity of the wave function, the role of quantum statistics in multi-particle systems, the possibility of order in momentum space—that eventually coalesced into a new conception of systems of equal particles. In particular, it was London's clarification of Bose-Einstein condensation that enabled him to formulate the notion of superfluids, and led him to the recognition that quantum mechanics was not, as it was commonly assumed, relevant exclusively as a micromechanics.

# Hydrodynamics of Superfluid Quantum Space: de Broglie interpretation of the quantum mechanics. (arXiv:1707.08508v1 [quant-ph])

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on 2017-7-27 2:50am GMT

Authors: Valeriy I. Sbitnev

The ubiquitous ether coming from the ancient times up to middle of the twenty century is replaced by a superfluid quantum space. It represents by itself a Bose-Einstein condensate consisting of enormous amount of virtual particle-antiparticle pairs emerging and disappearing in an infinitely ongoing dance. Flowing of this medium in the non-relativistic limit is described by the modified Navier-Stokes equation along with the continuity equation. The first equation admits the splitting on to two coupled equations. They are the quantum Hamilton-Jacobi equation and the equation for vorticity. The quantum Hamilton-Jacoby equation paired with the continuity equation can be reduced to the \Schrodinger equation. These two equations representing the kernel of the Bohmian mechanics give finding bundle of the Bohmian trajectories. Whereas the vorticity equation gives solutions for vortices moving along such trajectories. As the result we come to the de Broglie's interpretation of quantum mechanics according to which there is a pilot-wave guiding the particle (in our case it is a vortex clot) from a source up to its detection along an optimal path that is the Bohmian trajectory.

# Simultaneous weak measurement of non-commuting observables. (arXiv:1707.08276v1 [quant-ph])

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on 2017-7-27 2:50am GMT

In contrast to a projective quantum measurement in which the system is projected onto an eigenstate of the measured operator, in a weak measurement the system is only weakly perturbed while only partial information on the measured observable is obtained. A full description of such measurement should describe the measurement protocol and provide an explicit form of the measurement operator that transform the quantum state to its post measurement form. A simultaneous measurement of non-commuting observables cannot be projective, however the strongest possible such measurement can be defined as providing their values at the smallest uncertainty limit. Starting with the Arthurs and Kelly (AK) protocol for such measurement of position and momentum, we derive a systematic extension to a corresponding weak measurement along three steps: First, a plausible form of the weak measurement operator analogous to the Gaussian Kraus operator often used to model a weak measurement of a single observable is obtained by projecting a na\"ive extension (valid for commuting observable) onto the corresponding Gabor space. Second, we show that the so obtained set of measurement operators satisfies the normalization condition for the probability to obtain given values of the position and momentum in the weak measurement operation, namely that this set constitutes a positive operator valued measure (POVM) in the position-momentum space. Finally, we show that the so-obtained measurement operator corresponds to a generalization of the AK measurement protocol in which the initial detector wavefunctions is suitable broadened.

# The photon identification loophole in EPRB experiments: computer models with single-wing selection. (arXiv:1707.08307v1 [quant-ph])

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on 2017-7-27 2:50am GMT

Authors: H. De Raedt, K. Michielsen, K. Hess

Recent Einstein-Podolsky-Rosen-Bohm experiments [M. Giustina et al. Phys. Rev. Lett. 115, 250401 (2015); L. K. Shalm et al. Phys. Rev. Lett. 115, 250402 (2015)] that claim to be loophole free are scrutinized and are shown to suffer a photon identification loophole. The combination of a digital computer and discrete-event simulation is used to construct a minimal but faithful model of the most perfected realization of these laboratory experiments. In contrast to prior simulations, all photon selections are strictly made, as they are in the actual experiments, at the local station and no other "post-selection" is involved. The simulation results demonstrate that a manifestly non-quantum model that identifies photons in the same local manner as in these experiments can produce correlations that are in excellent agreement with those of the quantum theoretical description of the corresponding thought experiment, in conflict with Bell's theorem. The failure of Bell's theorem is possible because of our recognition of the photon identification loophole. Such identification measurement-procedures are necessarily included in all actual experiments but are not included in the theory of Bell and his followers.

# Finding causal structure

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## Philsci-Archive: No conditions. Results ordered -Date Deposited.

on 2017-7-26 5:24pm GMT
Ross, Lauren N. (2017) Finding causal structure. [Preprint]

# Quantum to classical transition induced by gravitational time dilation

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## PRA: Fundamental concepts

on 2017-7-26 2:00pm GMT

Author(s): Boris Sokolov, Iiro Vilja, and Sabrina Maniscalco

We study the loss of quantumness caused by time dilation [I. Pikovski, M. Zych, F. Costa, and Č. Brukner, Nat. Phys. 11, 668 (2015)] for a Schrödinger cat state. We give a holistic view of the quantum to classical transition by comparing the dynamics of several nonclassicality indicators, such as th...

[Phys. Rev. A 96, 012126] Published Wed Jul 26, 2017

# Interpretation miniatures. (arXiv:1703.08341v2 [quant-ph] UPDATED)

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on 2017-7-26 4:46am GMT

Authors: H. Nikolic

Most physicists do not have patience for reading long and obscure interpretation arguments and disputes. Hence, to attract attention of a wider physics community, in this paper various old and new aspects of quantum interpretations are explained in a concise and simple (almost trivial) form. About the "Copenhagen" interpretation, we note that there are several different versions of it and explain how to make sense of "local non-reality" interpretation. About the many-world interpretation, we explain that it is neither local nor non-local, that it cannot explain the Born rule, that it suffers from the preferred basis problem, and that quantum suicide cannot be used to test it. About the Bohmian interpretation, we explain that it is analogous to dark matter, use it to explain that there is no big difference between non-local correlation and non-local causation, and use some condensed-matter ideas to outline how non-relativistic Bohmian theory could be a theory of everything. We also explain how different interpretations can be used to demystify the delayed choice experiment, to resolve the problem of time in quantum gravity, and to provide alternatives to quantum non-locality. Finally, we explain why is life compatible with the 2nd law.

# On two recent proposals for witnessing nonclassical gravity. (arXiv:1707.07974v1 [quant-ph])

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on 2017-7-26 4:46am GMT

Authors: Michael J. W. Hall, Marcel Reginatto

Two very similar proposals have been made recently for witnessing nonclassical features of gravity, by Marletto and Vedral (arxiv.org/abs/1707.06036) and by Bose et al. (arXiv:1707.06050). However, while these proposals are asserted to be very general, they are in fact based on a very strong claim: that quantum systems cannot become entangled via a classical intermediary. We point out that the support provided for this claim is only applicable to a very limited class of quantum-classical interaction models, such as the Koopman model. We show that the claim is also valid for mean-field models, but that it is contradicted by explicit counterexamples based on the configuration-ensemble model. Thus, neither proposal provides a definitive test of nonclassical gravity.

# Velocity-dependent forces, Maxwell's demon, and the quantum theory. (arXiv:1707.08059v1 [quant-ph])

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on 2017-7-26 2:18am GMT

Authors: J.D. Franson

An atom moving in a focused laser beam will experience a velocity-dependent dipole force due to the Doppler effect, which allows the operation of a Maxwell's demon. Photon scattering and other forms of dissipation can be negligibly small, which appears to contradict quantum information proofs that a Maxwell's demon must dissipate a minimum amount of energy. We resolve this 'paradox' by showing that Schrodinger's equation does not predict a velocity-dependent dipole force. Forces of that kind have been observed experimentally, however, and we show that Heisenberg's equation does predict a velocity-dependent dipole force in agreement with experiment, provided that the total time derivative of an operator is evaluated along the trajectory of an atom.

# Taming the Delayed Choice Quantum Eraser. (arXiv:1707.07884v1 [quant-ph])

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on 2017-7-26 2:18am GMT

Authors: Johannes Fankhauser

In this paper I discuss the delayed choice quantum eraser experiment by giving a straightforward account in standard quantum mechanics. At first glance, the experiment suggests that measurements on one part of an entangled photon pair (the idler) can be employed to control whether the measurement outcome of the other part of the photon pair (the signal) produces interference fringes at a screen after being sent through a double slit. Significantly, the choice whether there is interference or not can be made long after the signal photon encounters the screen. The results of the experiment have been alleged to invoke some sort of 'backwards in time influences'. I argue that in the standard collapse interpretation the issue can be eliminated by taking into account the collapse of the overall entangled state due to the signal photon. Likewise, in the de Broglie-Bohm picture the particle's trajectories can be given a well-defined description at any instant of time during the experiment. Thus, there is no need to resort to any kind of 'backwards in time influence'. As a matter of fact, the delayed choice quantum eraser experiment turns out to resemble a Bell-type measurement, and so there really is no mystery.

# Nonlinear, nonequilibrium and collective dynamics in a periodically modulated cold atom system

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## ScienceDirect Publication: Physics Reports

on 2017-7-26 12:12am GMT
Publication date: Available online 22 July 2017
Source:Physics Reports
Author(s): Geol Moon, Myoung-Sun Heo, Yonghee Kim, Heung-Ryoul Noh, Wonho Jhe
The physics of critical phenomena in a many-body system far from thermal equilibrium is an interesting and important issue to be addressed both experimentally and theoretically. The trapped cold atoms have been actively used as a clean and versatile simulator for classical and quantum-mechanical systems, deepening understanding of the many-body physics behind. Here we review the nonlinear and collective dynamics in a periodically modulated magneto-optically trapped cold atoms. By temporally modulating the intensity of the trapping lasers with the controlled phases, one can realize two kinds of nonlinear oscillators, the parametrically driven oscillator and the resonantly driven Duffing oscillator, which exhibit the dynamical bistable states. Cold atoms behave not only as the single-particle nonlinear oscillators, but also as the coupled oscillators by the light-induced inter-atomic interaction, which leads to the phase transitions far from equilibrium in a way similar to the phase transition in equilibrium. The parametrically driven cold atoms show the ideal mean-field symmetry-breaking transition, and the symmetry is broken with respect to time translation by the modulation period. Such a phase transition results from the cooperation and competition between the inter-particle interaction and the fluctuations, which lead to the nonlinear switching of atoms between the vibrational states, and the experimentally measured critical characteristics prove it as the ideal mean-field transition class. On the other hand, the resonantly driven cold atoms that possess the coexisting periodic attractors exhibit the kinetic phase transition analogous to the discontinuous gas-liquid phase transition in equilibrium, and interestingly the global interaction between atoms causes the shift of the phase-transition boundary. We demonstrate that the temporally driven cold atom system serves as a unique and controllable platform suitable for investigating the nonlinear dynamics of many-body cold atoms far from equilibrium and for relating the relevant dynamics to other domains of physics. The results presented in this article may be useful for better understanding of the fundamentals of critical phenomena occurring in a many-body system far from thermal equilibrium, which still demands further studies both experimental and theoretical.

# Geometry and non-adiabatic response in quantum and classical systems

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## ScienceDirect Publication: Physics Reports

on 2017-7-26 12:12am GMT
Publication date: Available online 21 July 2017
Source:Physics Reports
Author(s): Michael Kolodrubetz, Dries Sels, Pankaj Mehta, Anatoli Polkovnikov
In these lecture notes, partly based on a course taught at the Karpacz Winter School in March 2014, we discuss the close connections between non-adiabatic response of a system with respect to macroscopic parameters and the geometry of quantum and classical states. We center our discussion around adiabatic gauge potentials, which are the generators of unitary basis transformations in quantum systems and generators of special canonical transformations in classical systems. In quantum systems, expectation values of these potentials in the eigenstates are the Berry connections and the covariance matrix of these gauge potentials is the geometric tensor, whose antisymmetric part defines the Berry curvature and whose symmetric part is the Fubini-Study metric tensor. In classical systems one simply replaces the eigenstate expectation value by an average over the micro-canonical shell. We express the non-adiabatic response of the physical observables of the system through these gauge potentials. We also demonstrate the close connection of the geometric tensor to the notions of Lorentz force and renormalized mass. We show how one can use this formalism to derive equations of motion for slow macroscopic parameters coupled to fast microscopic degrees of freedom to reproduce and even go beyond macroscopic Hamiltonian dynamics. Finally, we illustrate these ideas with a number of simple examples and highlight a few more complicated ones drawn from recent literature.

# Digital Quantum Simulation of Minimal AdS/CFT

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## PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

on 2017-7-25 2:00pm GMT

Author(s): L. García-Álvarez, I. L. Egusquiza, L. Lamata, A. del Campo, J. Sonner, and E. Solano

We propose the digital quantum simulation of a minimal $\mathrm{AdS}/\mathrm{CFT}$ model in controllable quantum platforms. We consider the Sachdev-Ye-Kitaev model describing interacting Majorana fermions with randomly distributed all-to-all couplings, encoding nonlocal fermionic operators onto qubits to efficiently im...

[Phys. Rev. Lett. 119, 040501] Published Tue Jul 25, 2017

# Quantum sensing

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## Recent Articles in Rev. Mod. Phys.

on 2017-7-25 2:00pm GMT

Author(s): C. L. Degen, F. Reinhard, and P. Cappellaro

Quantum technologies are increasingly driving the field of precision metrology. While current techniques for sensing and recording time rely on classical devices, quantum sensors exploit quantum systems to reach unprecedented levels of precision. The working part of the sensor contains one or a few qubits, and resources like quantum entanglement are chosen and tailored to maximize sensitivity. This review introduces quantum sensing from the perspective of working experimentalists, with specific sensor implementations, concepts and methods, and recent developments.

[Rev. Mod. Phys. 89, 035002] Published Tue Jul 25, 2017

# Incompatible multiple consistent sets of histories and measures of quantumness

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## PRA: Fundamental concepts

on 2017-7-25 2:00pm GMT

Author(s): J. J. Halliwell

In the consistent histories approach to quantum theory probabilities are assigned to histories subject to a consistency condition of negligible interference. The approach has the feature that a given physical situation admits multiple sets of consistent histories that cannot in general be united int...

[Phys. Rev. A 96, 012123] Published Tue Jul 25, 2017

# Effects of the generalized uncertainty principle on the thermal properties of Kemmer oscillator. (arXiv:1707.07238v1 [hep-th])

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on 2017-7-25 2:05am GMT

A series of aspects of the quantum gravity predict a modification in the Heisenberg uncertainty principle to the generalized uncertainty principle (GUP). In the present work, using the momentum space representation, we study the behavior of the Kemmer oscillator in the context of the GUP. The wave function, the probability densities, and the energy spectrum are obtained analytically. Furthermore, the thermodynamic properties of the system are investigated via numerical method and the influence of GUP on thermodynamic functions is also discussed.

# Measurement and Macroscopicity: Overcoming Conceptual Imprecision in Quantum Measurement Theory. (arXiv:1707.07561v1 [quant-ph])

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on 2017-7-25 2:05am GMT

Authors: Gregg Jaeger

John S. Bell is well known for the result now referred to simply as "Bell's theorem," which removed from serious consideration by physics of local hidden-variable theories. Under these circumstances, if quantum theory is to serve as a truly {\em fundamental} theory, conceptual precision in its interpretation is not only even more desirable but paramount. John Bell was accordingly concerned about what he viewed as conceptual imprecision, from the physical point of view, in the standard approaches to the theory. He saw this as most acute in the case of their treatment of {\em measurement at the level of principle}. Bell pointed out that conceptual imprecision is reflected in the terminology of the theory, a great deal of which he deemed worthy of banishment from discussions of principle. For him, it corresponded to a set of what he saw as vague and, in some instances, outright destructive concepts. Here, I consider this critique of standard quantum measurement theory and some alternative treatments wherein he saw greater conceptual precision, and make further suggestions as to how to proceed along the lines he advocated.

# Decision Theory with a Hilbert Space as Possibility Space. (arXiv:1707.07556v1 [quant-ph])

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on 2017-7-25 2:05am GMT

In this paper, we propose an interpretation of the Hilbert space method used in quantum theory in the context of decision making under uncertainty. For a clear comparison we will stay as close as possible to the framework of SEU suggested by Savage. We will use the Ellsberg-paradox to illustrate the potential of our approach to deal with well-known paradoxa of decision theory.

# The curious case of the double-slit experiment and a black hole. (arXiv:1707.06995v1 [quant-ph])

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on 2017-7-25 2:04am GMT

Authors: Satish Ramakrishna, Onuttom Narayan

This experiment was conceived of as a method of transmitting information from inside a black hole to the outside. As it turns out, it doesn't work in the form described (and possibly not in any form), but the way in which Nature prevents quantum-mechanical effects from transmitting usable information using quantum correlations is illuminating. In the process, one can learn some quantum theory, as well as quantum optics.

The proposed scheme uses a double-slit experiment, in the manner of the Delayed Choice set up \cite{Scully1} \cite{Scully2}, where the region where the interference takes place (between "signal" photons) is spatially separated from the region where the Delayed Choice (with "idler" photons) is made. Indeed, this Double-Delayed Choice, which is this thought experiment, has one of the idler photons slip inside the event horizon and serves as the method to attempt to communicate from the inside to the outside.

# Comment to "How does Casimir energy fall? IV. Gravitational interaction of regularized quantum vacuum energy" by K A Milton et al., Phys Rev D 89 064027 (2014). (arXiv:1707.07627v1 [gr-qc])

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on 2017-7-25 2:04am GMT

Authors: Massimo Cerdonio, Carlo Rovelli

The Paper actually concerns a toy model, not physical Casimir cavities made of conducting plates, but the results are taken implicitly to apply in general. We question on general physical grounds one basic assumption and the results of a renormalization procedure. Then, for physical systems, i) considering condensed matter theory/experiments, we find strong evidence against the conclusive claims concerning a putative and dominating surface energy present individually on the plates, and ii) we propose two experiments with physical Casimir cavities to show in detail that the results of the renormalization in this case look somewhat paradoxical. In any case the proposed experiments appear to be feasible and thus it could be tested if the putative self-energies of the plates are indeed there in a physical Casimir cavity, or if the toy model of the Paper has by contrast no connection with physical reality. However at the moment the authors are not legitimate to issue as conclusive claims statements like- refute the claim sometimes attributed to Feynman that virtual photons do not gravitate -

# Betting on Quantum Objects

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## Philsci-Archive: No conditions. Results ordered -Date Deposited.

on 2017-7-24 5:09pm GMT
Steeger, Jeremy (2017) Betting on Quantum Objects. [Preprint]

# It ain’t necessarily so: Gravitational Waves and Energy Transport

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## Philsci-Archive: No conditions. Results ordered -Date Deposited.

on 2017-7-24 5:08pm GMT
Duerr, Patrick (2017) It ain’t necessarily so: Gravitational Waves and Energy Transport. [Preprint]

# Twelve years before the quantum no-cloning theorem. (arXiv:1707.06910v1 [physics.hist-ph])

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on 2017-7-24 3:56am GMT

Authors: Juan Ortigoso

It is universally accepted that the quantum no-cloning theorem was not officially discovered until 1982. I show here that an article published in 1970 [J. L. Park, Foundations of Physics, 1, 23-33 (1970)] contained an explicit proof of the theorem. Park's demonstration has been overlooked until now and the paper remains virtually unknown. Reasons and implications of this fact are analyzed in the light of existing explanations concerning the genesis of the theorem.

# A Schema for Duality, Illustrated by Bosonization. (arXiv:1707.06681v1 [physics.hist-ph])

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on 2017-7-24 3:56am GMT

Authors: Sebastian De Haro, Jeremy Butterfield

In this paper we present a schema for describing dualities between physical theories (Sections 2 and 3), and illustrate it in detail with the example of bosonization: a boson-fermion duality in two-dimensional quantum field theory (Sections 4 and 5).

The schema develops proposals in De Haro (2016, 2016a): these proposals include construals of notions related to duality, like representation, model, symmetry and interpretation. The aim of the schema is to give a more precise criterion for duality than has so far been considered.

The bosonization example, or boson-fermion duality, has the feature of being simple yet rich enough to illustrate the most relevant aspects of our schema, which also apply to more sophisticated dualities. The richness of the example consists, mainly, in its concern with two non-trivial quantum field theories: including massive Thirring-sine-Gordon duality, and non-abelian bosonization.

This prompts two comparisons with the recent literature on dualities:---

(a) Unlike the standard cases of duality in quantum field theory and string theory, where only specific simplifying limits of the theories are explicitly known, the boson-fermion duality is known to hold exactly. This exactness can be exhibited explicitly.

(b) The bosonization example illustrates both the cases of isomorphic and non-isomorphic models: which we believe the literature on dualities has not so far discussed.