2021年11月15日 星期一 下午6:18 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Healey, Richard (2021) Beyond Bell? [Preprint]

Quantum technologies need a quantum energy initiative. (arXiv:2111.09241v2 [quant-ph] UPDATED)

上午9:19 | | | A. Auffèves | | | quant-ph updates on arXiv.org |

Quantum technologies are currently the object of high expectations from governments and private companies, as they hold the promise to shape safer and faster ways to exchange and treat information. However, despite its major potential impact for industry and society, the question of their energetic footprint has remained in a blind spot of current deployment strategies. In this Perspective, I argue that quantum technologies must urgently plan for the creation and structuration of a transverse quantum energy initiative, connecting quantum thermodynamicists, computer scientists, experimenters and engineers. Such initiative is the only path towards sustainable quantum technologies, help reducing the cost of classical information processing, and possibly bring out an energetic quantum advantage.

The Quantum Eraser Paradox. (arXiv:2111.09347v1 [quant-ph])

上午9:19 | | | physics.hist-ph updates on arXiv.org |

Authors: Colm Bracken, Jonte R. Hance, Sabine Hossenfelder

The Delayed-Choice Quantum Eraser experiment is commonly interpreted as implying that in quantum mechanics a choice made at one time can influence an earlier event. We here suggest an extension of the experiment that results in a paradox when interpreted using a local realist interpretation combined with backward causation (“retrocausality”). We argue that resolving the paradox requires giving up the idea that, in quantum mechanics, a choice can influence the past, and that it instead requires a violation of Statistical Independence without retrocausality. We speculate what the outcome of the experiment would be.

上午9:19 | | | gr-qc updates on arXiv.org |

Authors: Andrew J. S. Hamilton

This paper presents a pedagogical introduction to the issue of how to implement Lorentz transformations in relativistic visualization. The most efficient approach is to use the even geometric algebra in 3+1 spacetime dimensions, or equivalently complex quaternions, which are fast, compact, and robust, and straightforward to compose, interpolate, and spline. The approach has been incorporated into the Black Hole Flight Simulator, an interactive general relativistic ray-tracing program developed by the author.

Embedding Causal Sets into Minkowski Spacetime. (arXiv:2111.09331v1 [gr-qc])

上午9:19 | | | gr-qc updates on arXiv.org |

Authors: Steven Johnston

We present a new method for embedding a causal set into an interval of Minkowski spacetime. The method uses spacetime volumes for causally related elements to define causal set analogs of Minkowski inner products. These are used to construct matrices of inner products which are then factored using the singular value decomposition to give coordinates in Minkowski spacetime. Results are presented showing good quality embeddings into Minkowski spacetime for dimensions d=2,3,4. The method applies in any dimension and does not require spacelike distances to be used as an input. It offers a new way to define spatial orientation and spacelike distances in a causal set.

Islands in Multiverse Models. (arXiv:2108.01278v2 [hep-th] UPDATED)

上午9:19 | | | gr-qc updates on arXiv.org |

Authors: Sergio E. Aguilar-Gutierrez, Aidan Chatwin-Davies, Thomas Hertog, Natalia Pinzani-Fokeeva, Brandon Robinson

We consider multiverse models in two-dimensional linear dilaton-gravity theories as toy models of false vacuum eternal inflation. Coupling conformal matter we calculate the Von Neumann entropy of subregions. When these are sufficiently large we find that an island develops covering most of the rest of the multiverse, leading to a Page-like transition. This resonates with a description of multiverse models in semiclassical quantum cosmology, where a measure for local predictions is given by saddle point geometries which coarse-grain over any structure associated with eternal inflation beyond one’s patch.

2021年11月19日 星期五 下午5:55 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Merritt, David (2021) MOND and Methodology. Karl Popper’s Science and Philosophy. pp. 69-96.

Autonomy generalised; or, Why doesn’t physics matter more?

2021年11月19日 星期五 下午5:54 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Robertson, Katie (2021) Autonomy generalised; or, Why doesn’t physics matter more? [Preprint]

What’s so special about initial conditions? Understanding the past hypothesis in directionless time

2021年11月19日 星期五 下午5:50 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Farr, Matt (2021) What’s so special about initial conditions? Understanding the past hypothesis in directionless time. [Preprint]

The physics and metaphysics of Tychistic Bohmian Mechanics

2021年11月15日 星期一 下午6:20 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Duerr, Patrick and Ehmann, Alexander (2021) The physics and metaphysics of Tychistic Bohmian Mechanics. Stuidies in History and Philosophy of Science Part A, 90. pp. 168-183.

]]>上午9:54 | | | N. L. Chuprikov | | | quant-ph updates on arXiv.org |

Using the one-dimensional Schr\”{o}dinger equation as an example, it is shown that for any self-adjoint operator it is possible to uniquely predict the value of the corresponding observable (including momentum, kinetic and total energy of the particle) at that spatial point where the particle will be accidentally detected at a given instant of time. It is shown that the Schr\”{o}dinger formalism ensures the fulfillment of the relations of wave-particle duality, which connect the energy and momentum of a particle with the frequency and wave number of the wave function, for any spatial point and any instant of time.

Quantum Correlations in the Minimal Scenario. (arXiv:2111.06270v1 [quant-ph])

上午9:54 | | | Thinh P. Le, Chiara Meroni, Bernd Sturmfels, Reinhard F. Werner, Timo Ziegler | | | quant-ph updates on arXiv.org |

In the minimal scenario of quantum correlations, two parties can choose from two observables with two possible outcomes each. Probabilities are specified by four marginals and four correlations. The resulting four-dimensional convex body of correlations, denoted $\mathcal{Q}$, is fundamental for quantum information theory. It is here studied through the lens of convex algebraic geometry. We review and systematize what is known and add many details, visualizations, and complete proofs. A new result is that $\mathcal{Q}$ is isomorphic to its polar dual. The boundary of $\mathcal{Q}$ consists of three-dimensional faces isomorphic to elliptopes and sextic algebraic manifolds of exposed extreme points. These share all basic properties with the usual maximally CHSH-violating correlations. These patches are separated by cubic surfaces of non-exposed extreme points. We provide a trigonometric parametrization of all extreme points, along with their exposing Tsirelson inequalities and quantum models. All non-classical extreme points (exposed or not) are self-testing, i.e., realized by an essentially unique quantum model.

Two principles, which are specific to the minimal scenario, allow a quick and complete overview: The first is the pushout transformation, the application of the sine function to each coordinate. This transforms the classical polytope exactly into the correlation body $\mathcal{Q}$, also identifying the boundary structures. The second principle, self-duality, reveals the polar dual, i.e., the set of all Tsirelson inequalities satisfied by all quantum correlations. The convex body $\mathcal{Q}$ includes the classical correlations, a cross polytope, and is contained in the no-signaling body, a 4-cube. These polytopes are dual to each other, and the linear transformation realizing this duality also identifies $\mathcal{Q}$ with its dual.

Insights on Entanglement Entropy in $1+1$ Dimensional Causal Sets. (arXiv:2111.05879v1 [hep-th])

上午9:53 | | | gr-qc updates on arXiv.org |

Authors: Théo Keseman, Hans J. Muneesamy, Yasaman K. Yazdi

Entanglement entropy in causal sets offers a fundamentally covariant characterisation of quantum field degrees of freedom. A known result in this context is that the degrees of freedom consist of a number of contributions that have continuum-like analogues, in addition to a number of contributions that do not. The latter exhibit features below the discreteness scale and are excluded from the entanglement entropy using a “truncation scheme”. This truncation is necessary to recover the standard spatial area law of entanglement entropy. In this paper we build on previous work on the entanglement entropy of a massless scalar field on a causal set approximated by a 1+1D causal diamond in Minkowski spacetime. We present new insights into the truncated contributions, including evidence that they behave as fluctuations and encode features specific to a particular causal set sprinkling. We extend previous results in the massless theory to include R\’enyi entropies and include new results for the massive theory. We also discuss the implications of our work for the treatment of entanglement entropy in causal sets in more general settings.

Stochastic Quantization of Relativistic Theories. (arXiv:2103.02501v3 [gr-qc] UPDATED)

上午9:53 | | | gr-qc updates on arXiv.org |

Authors: Folkert Kuipers

It was shown recently that stochastic quantization can be made into a well defined quantization scheme on (pseudo-)Riemannian manifolds using second order differential geometry, which is an extension of the commonly used first order differential geometry. In this letter, we show that restrictions to relativistic theories can be obtained from this theory by imposing a stochastic energy-momentum relation. In the process, we derive non-perturbative quantum corrections to the line element as measured by scalar particles. Furthermore, we extend the framework of stochastic quantization to massless scalar particles.

Cyclic Cosmology and Geodesic Completeness. (arXiv:2110.15380v2 [gr-qc] UPDATED)

上午9:53 | | | gr-qc updates on arXiv.org |

Authors: William H. Kinney, Nina K. Stein (Univ. at Buffalo, SUNY)

We consider recently proposed bouncing cosmological models for which the Hubble parameter is periodic in time, but the scale factor grows from one cycle to the next as a mechanism for shedding entropy. Since the scale factor for a flat universe is equivalent to an overall conformal factor, it has been argued that this growth corresponds to a physically irrelevant rescaling, and such bouncing universes can be made perfectly cyclic, extending infinitely into the past and future. We show that any bouncing universe which uses growth of the scale factor to dissipate entropy must necessarily be geodesically past-incomplete, and therefore cannot be truly cyclic in time.

Viewing quantum charge from the classical vantage point

2021年11月12日 星期五 下午5:10 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

GIlton, Marian J. R. (2021) Viewing quantum charge from the classical vantage point. In: UNSPECIFIED.

Irreversible (One-hit) and Reversible (Sustaining) Causation

2021年11月12日 星期五 下午5:08 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Ross, Lauren N. and Woodward, James (2021) Irreversible (One-hit) and Reversible (Sustaining) Causation. In: UNSPECIFIED.

2021年11月12日 星期五 下午5:07 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Giovanelli, Marco (2021) Geometrization vs. Unification. The Reichenbach-Einstein Quarrel about the Fernparallelismus Field Theory. [Preprint]

Pseudorandomness in Simulations and Nature

2021年11月12日 星期五 下午5:05 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Abrams, Marshall (2021) Pseudorandomness in Simulations and Nature. In: UNSPECIFIED.

One world is (probably) just as good as many

2021年11月10日 星期三 下午6:03 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Steeger, Jeremy (2021) One world is (probably) just as good as many. [Preprint]

2021年11月10日 星期三 下午5:59 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Lam, Vincent and Wuthrich, Christian (2021) Laws beyond spacetime. [Preprint]

On the (Im)possibility of Scalable Quantum Computing

2021年11月10日 星期三 下午5:58 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Knight, Andrew (2021) On the (Im)possibility of Scalable Quantum Computing. [Preprint]

Spacetime: Function and Approximation

2021年11月10日 星期三 下午5:58 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Baron, Sam (2021) Spacetime: Function and Approximation. [Preprint]

How to Make Presentism Consistent with Special Relativity

2021年11月10日 星期三 下午5:56 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Balaguer, Mark (2021) How to Make Presentism Consistent with Special Relativity. In: UNSPECIFIED.

]]>上午10:24 | | | Charis Anastopoulos, Bei-Lok Hu | | | quant-ph updates on arXiv.org |

Gravitational decoherence (GD) refers to the effects of gravity in actuating the classical appearance of a quantum system. Because the underlying processes involve issues in general relativity (GR), quantum field theory (QFT) and quantum information, GD has fundamental theoretical significance. There is a great variety of GD models, many of them involving physics that diverge from GR and/or QFT. This overview has two specific goals along one central theme: (i) present theories of GD based on GR and QFT and explore their experimental predictions; (ii) place other theories of GD under the scrutiny of GR and QFT, and point out their theoretical differences. We also describe how GD experiments in space in the coming decades can provide evidences at two levels: a) discriminate alternative quantum theories and non-GR theories; b) discern whether gravity is a fundamental or an effective theory.

Spectra of Neutron Wave Functions in Earth’s Gravitational Field. (arXiv:2111.02769v1 [quant-ph])

上午10:24 | | | Martin Suda, Manfried Faber, Joachim Bosina, Tobias Jenke, Christian Käding, Jakob Micko, Mario Pitschmann, Hartmut Abele | | | quant-ph updates on arXiv.org |

The time evolution of a quantum wave packet in the linear gravity potential is known as Quantum Bouncing Ball. The qBounce collaboration recently observed such a system by dropping wave packets of ultracold neutrons by a height of roughly 30 microns. In this article, space and momentum spectra as well as Wigner functions of the neutron wave functions in the gravitational field of the Earth are analyzed. We investigate the quantum states in the “preparation region”, into which they transition after exiting a narrow double-mirror system and where we would expect to observe free fall and bounces in classical physics. For this, we start from the stationary solutions and eigenvalues of the Schr\”odinger equation in terms of Airy functions and their zeros. Subsequently, we examine space and momentum distributions as well as Wigner functions in phase space for pure and mixed quantum states. The eventual influence of Yukawa-like forces for small distances of several micrometers from the mirror is included through first order perturbation calculations. Those allow us to study the resulting modifications of space and momentum distributions, and phase space functions.

Is there a classical model of Wigner’s friend?. (arXiv:2111.02807v1 [quant-ph])

上午10:24 | | | Anthony Sudbery | | | quant-ph updates on arXiv.org |

“Wigner’s friend” refers to a quantum process of which different observers, following the rules of quantum mechanics, give contradictory descriptions. Lostaglio and Bowles have recently claimed to describe a classical system showing the same effect. It is argued that this claim is not justified.

上午10:24 | | | Mao-Sheng Li, Zhu-Jun Zheng | | | quant-ph updates on arXiv.org |

Quantum nonlocality without entanglement is a fantastic phenomenon in quantum theory. This kind of quantum nonlocality is based on the task of local discrimination of quantum states. Recently, Bandyopadhyay and Halder [arXiv:2104.11933] studied the problem: is there any set of orthogonal states which can be locally distinguishable, but under some orthogonality preserving local measurement, each outcome will lead to a locally indistinguishable set. We say that the set with such property has hidden nonlocality. Moreover, if such phenomenon can not arise from discarding subsystems which is termed as local irredundancy, we call it genuine hidden nonlocality. There, they presented several sets of entangled states with genuine hidden nonlocality. However, they doubted the existence of a set without entanglement but with genuine hidden nonlocality. In this paper, we eliminate this doubt by constructing a series of sets without entanglement but whose nonlocality can be genuinely activated. We derive a method to tackle with the local irredundancy problem which is a key tricky for the systems whose local dimensions are composite numbers. As Bandyopadhyay and Halder have been pointed out, sets with genuine hidden nonloclity would lead to some applications on the data hiding.

上午10:24 | | | Nelson Pinto-Neto | | | quant-ph updates on arXiv.org |

We review the de Broglie-Bohm quantum theory. It is an alternative description of quantum phenomena in accordance with all the quantum experiments already performed. Essentially, it is a dynamical theory about objectively real trajectories in the configuration space of the physical system under investigation. Hence, it is not necessarily probabilistic, and it dispenses with the collapse postulate, making it suitable to be applied to cosmology. The emerging cosmological models are usually free of singularities, with a bounce connecting a contracting era with an expanding phase, which we are now observing. A theory of cosmological perturbations can also be constructed under this framework, which can be successfully confronted with current observations, and can complement inflation or even be an alternative to it.

Non-Local Boxes for Networks. (arXiv:2102.03597v2 [quant-ph] UPDATED)

上午10:24 | | | Jean-Daniel Bancal, Nicolas Gisin | | | quant-ph updates on arXiv.org |

Nonlocal boxes are conceptual tools that capture the essence of the phenomenon of quantum non-locality, central to modern quantum theory and quantum technologies. We introduce network nonlocal boxes tailored for quantum networks under the natural assumption that these networks connect independent sources and do not allow signaling. Hence, these boxes satisfy the No-Signaling and Independence (NSI) principle. For the case of boxes without inputs, connecting pairs of bipartite sources and producing binary outputs, we prove that the sources and boxes producing local random outputs and maximal 2-box correlations, i.e. $E_2=\sqrt{2}-1$, $E_2^o=1$, are essentially unique.

上午10:24 | | | Riddhi Chatterjee, Sunandan Gangopadhyay, A. S. Majumdar | | | quant-ph updates on arXiv.org |

We study the spontaneous excitation of a two-level atom in the presence of a perfectly reflecting mirror, when the atom, or the mirror, is uniformly accelerating in the framework of the generalised uncertainty principle (GUP). The quantized scalar field obeys a modified dispersion relation leading to a GUP deformed Klein-Gordon equation. The solutions of this equation with suitable boundary conditions are obtained to calculate the spontaneous excitation probability of the atom for the two separate cases. We show that in the case when the mirror is accelerating, the GUP modulates the spatial oscillation of the excitation probability of the atom, thus breaking the symmetry between the excitation of an atom accelerating relative to a stationary mirror, and a stationary atom excited by an accelerating mirror. An explicit violation of the equivalence principle seems to be thus manifested. We further obtain an upper bound on the GUP parameter using standard values of the system parameters.

On a Quantum Weyl Curvature Hypothesis. (arXiv:2111.02137v1 [gr-qc] CROSS LISTED)

上午10:24 | | | Claus Kiefer | | | quant-ph updates on arXiv.org |

Roger Penrose’s Weyl Curvature Hypothesis states that the Weyl curvature is small at past singularities, but not at future singularities. We review the motivations for this conjecture and present estimates for the entropy of our Universe. We then extend this hypothesis to the quantum regime by demanding that the initial state of primordial quantum fluctuations be the adiabatic vacuum in a (quasi-) de~Sitter space. We finally attempt a justification of this quantum version from a fundamental theory of quantum gravity and speculate on its consequences in the case of a classically recollapsing universe.

Complexity Equals Anything?. (arXiv:2111.02429v1 [hep-th])

上午10:21 | | | gr-qc updates on arXiv.org |

Authors: Alexandre Belin, Robert C. Myers, Shan-Ming Ruan, Gábor Sárosi, Antony J. Speranza

We present a new infinite class of gravitational observables in asymptotically Anti-de Sitter space living on codimension-one slices of the geometry, the most famous of which is the volume of the maximal slice. We show that these observables display universal features for the thermofield-double state: they grow linearly in time at late times and reproduce the switch-back effect in shock wave geometries. We argue that any member of this class of observables is an equally viable candidate as the extremal volume for a gravitational dual of complexity.

上午10:21 | | | gr-qc updates on arXiv.org |

Authors: Yuewei Wen, Eva Nesbit, Dragan Huterer, Scott Watson

Standard cosmological data analyses typically constrain simple phenomenological dark-energy parameters, for example the present-day value of the equation of state parameter, $w_0$, and its variation with scale factor, $w_a$. However, results from such an analysis cannot easily indicate the presence of modified gravity. Even if general relativity does not hold, experimental data could still be fit sufficiently well by a phenomenological $w_0w_a$CDM, unmodified-gravity model. Hence, it would be very useful to know if there are generic signatures of modified gravity in standard analyses. Here we present, for the first time to our knowledge, a quantitative mapping showing how modified gravity models look when (mis)interpreted within the standard unmodified-gravity analysis. Scanning through a broad space of modified-gravity (Horndeski) models, and assuming a near-future survey consisting of CMB, BAO, and SNIa observations, we report values of the best-fit set of cosmological parameters including $(w_0, w_a)$ that would be inferred if modified gravity were at work. We find that modified gravity models that can masquerade as standard gravity lead to very specific biases in standard-parameter spaces. We also comment on implications for measurements of the amplitude of mass fluctuations described by the parameter $S_8$.

Unitarily inequivalent quantum cosmological bouncing models. (arXiv:2111.02963v1 [gr-qc])

上午10:21 | | | gr-qc updates on arXiv.org |

Authors: Jaime de Cabo Martin, Przemysław Małkiewicz, Patrick Peter

By quantising the background as well as the perturbations in a simple one fluid model, we show that there exists an ambiguity in the choice of relevant variables, potentially leading to incompatible observational physical predictions. In a classical or quantum inflationary background, the exact same canonical transformations lead to unique predictions, so the ambiguity we put forward demands a semiclassical background with a sufficiently strong departure from classical evolution. The latter condition happens to be satisfied in bouncing scenarios, which may thus be having predictability issues. Inflationary models could evade such a problem because of the monotonic behavior of their scale factor; they do, however, initiate from a singular state which bouncing scenarios aim at solving.

上午10:21 | | | gr-qc updates on arXiv.org |

Authors: Hervé Partouche, Nicolaos Toumbas, Balthazar de Vaulchier

We consider the Hartle-Hawking wavefunction of the universe defined as a Euclidean path integral that satisfies the “no-boundary proposal.” We focus on the simplest minisuperspace model that comprises a single scale factor degree of freedom and a positive cosmological constant. The model can be seen as a non-linear $\sigma$-model with a line-segment base. We reduce the path integral over the lapse function to an integral over the proper length of the base and use diffeomorphism-invariant measures for the ghosts and the scale factor. As a result, the gauge-fixed path integral is independent of the gauge. However, we point out that all field redefinitions of the scale factor degree of freedom yield different choices of gauge-invariant path-integral measures. For each prescription, we compute the wavefunction at the semi-classical level and find a different result. We resolve in each case the ambiguity in the form of the Wheeler-DeWitt equation at this level of approximation. By imposing that the Hamiltonians associated with these possibly distinct quantum theories are Hermitian, we determine the inner products of the corresponding Hilbert spaces and find that they lead to a universal norm, at least semi-classically. Quantum predictions are thus independent of the prescription at this level of approximation. Finally, all wavefunctions of the Hilbert spaces of the minisuperspace model we consider turn out to be non-normalizable, including the no-boundary states.

Complete Incompatibility, Support Uncertainty, and Kirkwood-Dirac Nonclassicality

2021年11月5日 星期五 下午6:00 | | | Stephan De Bièvre | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Stephan De Bièvre

For quantum systems with a finite dimensional Hilbert space of states, we show that the complete incompatibility of two observables—a notion we introduce—is equivalent to the large support uncertainty of all states. The Kirkwood-Dirac (KD) quasiprobability distribution of a state—which depends on th…

[Phys. Rev. Lett. 127, 190404] Published Fri Nov 05, 2021

Drawing Scales Apart: The Origins of Wilson’s Conception of Effective Field Theories

2021年11月5日 星期五 下午4:12 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Rivat, Sébastien (2021) Drawing Scales Apart: The Origins of Wilson’s Conception of Effective Field Theories.

Troubles with mathematical contents

2021年11月5日 星期五 下午4:12 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Facchin, Marco (2021) Troubles with mathematical contents. [Preprint]

“Fundamental” “constants” and precision tests of the standard model

2021年11月5日 星期五 下午4:08 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Koberinski, Adam (2021) “Fundamental” “constants” and precision tests of the standard model. In: UNSPECIFIED.

A generic approach to the quantum mechanical transition probability

2021年11月5日 星期五 下午3:47 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Niestegge, Gerd (2021) A generic approach to the quantum mechanical transition probability. [Preprint]

2021年11月4日 星期四 下午4:39 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Halvorson, Hans and Manchak, JB (2021) Closing the hole argument. [Preprint]

Structuralist Approaches to Bohmian Mechanics

2021年11月4日 星期四 下午4:37 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Lorenzetti, Lorenzo (2021) Structuralist Approaches to Bohmian Mechanics. [Preprint]

Bogoliubov’s correlations confirmed

2021年11月4日 星期四 上午8:00 | | | A. G. Truscott | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 04 November 2021; doi:10.1038/s41567-021-01406-w

Interacting quantum systems are difficult to formulate theoretically, but Nikolai Bogoliubov offered a workaround more than 70 years ago that has stood the test of time. Now, correlations that are a crucial feature of his theory have been observed.

Observation of pairs of atoms at opposite momenta in an equilibrium interacting Bose gas

2021年11月4日 星期四 上午8:00 | | | David Clément | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 04 November 2021; doi:10.1038/s41567-021-01381-2

Interactions between atoms in a Bose–Einstein condensate cause quantum fluctuations and the creation of additional correlations between pairs of atoms. These effects have now been directly observed, confirming long-standing theoretical predictions.

The Darwinian Tension: Romantic Science and the Causal Laws of Nature

2021年11月1日 星期一 上午11:44 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Greif, Hajo (2015) The Darwinian Tension: Romantic Science and the Causal Laws of Nature. Studies in History and Philosophy of Biological and Biomedical Sciences, 53. pp. 53-61. ISSN 1369-8486

]]>上午9:00 | | | Renato Renner, Jinzhao Wang | | | quant-ph updates on arXiv.org |

The black hole information puzzle arises from a discrepancy between conclusions drawn from general relativity and quantum theory about the nature of the radiation emitted by black holes. According to Hawking’s original argument, the radiation is thermal and its entropy thus increases monotonously as the black hole evaporates. Conversely, due to the reversibility of time evolution according to quantum theory, the radiation entropy should decrease in the final stages of evaporation, as predicted by the Page curve. This behaviour has been confirmed by new calculations based on the replica trick, which also exhibited its geometrical origin: spacetime wormholes that form between the replicas. Here we analyse the discrepancy between these and Hawking’s original conclusions from a quantum information theory viewpoint, using in particular the quantum de Finetti theorem. The theorem implies the existence of extra information, $W$, which plays the role of a reference. The entropy obtained via the replica trick can then be identified to be the entropy $S(R|W)$ of the radiation conditioned on the reference $W$, whereas Hawking’s original result corresponds to the non-conditional entropy $S(R)$. The entropy $S(R|W)$, which mathematically is an ensemble average, gains its physical meaning in a many-black-holes scenario. Our analysis hints at an interpretation of the replica wormholes as the geometrical representation of the correlation between the black holes, which is mediated by $W$. It also suggests an extension of the widely used random unitary model of black holes, which we support with some new non-trivial checks.

A convergent inflation hierarchy for quantum causal structures. (arXiv:2110.14659v1 [quant-ph])

上午9:00 | | | Laurens T. Ligthart, Mariami Gachechiladze, David Gross | | | quant-ph updates on arXiv.org |

A causal structure is a description of the functional dependencies between random variables. A distribution is compatible with a given causal structure if it can be realized by a process respecting these dependencies. Deciding whether a distribution is compatible with a structure is a practically and fundamentally relevant, yet very difficult problem. Only recently has a general class of algorithms been proposed: These so-called inflation techniques associate to any causal structure a hierarchy of increasingly strict compatibility tests, where each test can be formulated as a computationally efficient convex optimization problem. Remarkably, it has been shown that in the classical case, this hierarchy is complete in the sense that each non-compatible distribution will be detected at some level of the hierarchy. An inflation hierarchy has also been formulated for causal structures that allow for the observed classical random variables to arise from measurements on quantum states – however, no proof of completeness of this quantum inflation hierarchy has been supplied. In this paper, we construct a first version of the quantum inflation hierarchy that is provably convergent. From a technical point of view, convergence proofs are built on de Finetti Theorems, which show that certain symmetries (which can be imposed in convex optimization problems) imply independence of random variables (which is not directly a convex constraint). A main technical ingredient to our proof is a Quantum de Finetti Theorem that holds for general tensor products of $C^*$-algebras, generalizing previous work that was restricted to minimal tensor products.

上午9:00 | | | Tanay Kibe, Prabha Mandayam, Ayan Mukhopadhyay | | | quant-ph updates on arXiv.org |

This article reviews the progress in our understanding of the reconstruction of the bulk spacetime in the holographic correspondence from the dual field theory including an account of how these developments have led to the reproduction of the Page curve of the Hawking radiation from black holes. We review quantum error correction and relevant recovery maps with toy examples based on tensor networks, and discuss how it provides the desired framework for bulk reconstruction in which apparent inconsistencies with properties of the operator algebra in the dual field theory are naturally resolved. The importance of understanding the modular flow in the dual field theory has been emphasized. We discuss how the state-dependence of reconstruction of black hole microstates can be formulated in the framework of quantum error correction with inputs from extremal surfaces along with a quantification of the complexity of encoding of bulk operators. Finally, we motivate and discuss a class of tractable microstate models of black holes which can illuminate how the black hole complementarity principle can emerge operationally without encountering information paradoxes, and provide new insights into generation of desirable features of encoding into the Hawking radiation.

上午9:00 | | | Shira Chapman, Giuseppe Policastro | | | quant-ph updates on arXiv.org |

Quantum computational complexity estimates the difficulty of constructing quantum states from elementary operations, a problem of prime importance for quantum computation. Surprisingly, this quantity can also serve to study a completely different physical problem – that of information processing inside black holes. Quantum computational complexity was suggested as a new entry in the holographic dictionary, which extends the connection between geometry and information and resolves the puzzle of why black hole interiors keep growing for a very long time. In this pedagogical review, we present the geometric approach to complexity advocated by Nielsen and show how it can be used to define complexity for generic quantum systems; in particular, we focus on Gaussian states in QFT, both pure and mixed, and on certain classes of CFT states. We then present the conjectured relation to gravitational quantities within the holographic correspondence and discuss several examples in which different versions of the conjectures have been tested. We highlight the relation between complexity, chaos and scrambling in chaotic systems. We conclude with a discussion of open problems and future directions. This article was written for the special issue of EPJ-C Frontiers in Holographic Duality.

上午9:00 | | | Ricardo Gallego Torromé | | | quant-ph updates on arXiv.org |

The formal structure of Penrose’s gravitationally induced reduction of the wave function mechanism is analyzed. It is shown that pushing Penrose’s argument forward leads to the interpretation of quantum coherence in microscopic systems as an observable signature violation of general covariance. We discuss potential avenues to avoid this conclusion, among them emergent quantum mechanics and super-determinism.

Fundamental limits of quantum error mitigation. (arXiv:2109.04457v3 [quant-ph] UPDATED)

上午9:00 | | | Ryuji Takagi, Suguru Endo, Shintaro Minagawa, Mile Gu | | | quant-ph updates on arXiv.org |

The inevitable accumulation of errors in near-future quantum devices represents a key obstacle in delivering practical quantum advantage. This motivated the development of various quantum error-mitigation protocols, each representing a method to extract useful computational output by combining measurement data from multiple samplings of the available imperfect quantum device. What are the ultimate performance limits universally imposed on such protocols? Here, we derive a fundamental bound on the sampling overhead that applies to a general class of error-mitigation protocols, assuming only the laws of quantum mechanics. We use it to show that (1) the sampling overhead to mitigate local depolarizing noise for layered circuits — such as the ones used for variational quantum algorithms — must scale exponentially with circuit depth, and (2) the optimality of probabilistic error cancellation method among all strategies in mitigating a certain class of noise, demonstrating that our results provide a means to identify when a given quantum error-mitigation strategy is optimal and when there is potential room for improvement.

Change in Hamiltonian General Relativity with Spinors. (arXiv:2110.15266v1 [gr-qc])

上午9:00 | | | physics.hist-ph updates on arXiv.org |

Authors: J. Brian Pitts

In Hamiltonian GR, change has seemed to be missing, defined only asymptotically, or otherwise obscured at best. By construing change as essential time dependence, can one find change locally in Hamiltonian GR with spinors?

This paper is motivated by tendencies in space-time philosophy tends to slight fermionic/spinorial matter, in Hamiltonian GR to misplace changes of time coordinate, and in treatments of the Einstein-Dirac equation to include a gratuitous local Lorentz gauge symmetry. Spatial dependence is dropped in most of the paper. To include all and only the coordinate freedom, the Einstein-Dirac equation is investigated using the Schwinger time gauge and Kibble-Deser symmetric triad condition as a $3+1$ version of the DeWitt-Ogievetsky-Polubarinov nonlinear group realization formalism that dispenses with a tetrad and local Lorentz gauge freedom. Change is the lack of a time-like stronger-than-Killing field for which the Lie derivative of the metric-spinor complex vanishes. An appropriate $3+1$-friendly form of the Rosenfeld-Anderson-Bergmann-Castellani gauge generator $G$, a tuned sum of first class-constraints, changes the canonical Lagrangian by a total derivative and implements changes of time coordinate for solutions.

Unifying gravitational waves and dark energy. (arXiv:2110.14689v1 [gr-qc])

上午9:00 | | | gr-qc updates on arXiv.org |

Authors: Alice Garoffolo, Omar Contigiani

We present a unifying treatment for metric and scalar perturbations across different energy regimes in scalar-tensor theories of gravity. To do so, we introduce two connected symmetry-breaking patterns: one due to the acquisition of nontrivial vacuum expectation values by the fields and the other due to the distinction between background and perturbations that live on top of it. We show that the geometric optics approximation commonly used to enforce this separation is not self-consistent for high-frequency perturbations since gauge transformations mix different tensor and scalar sectors orders. We derive the equations of motions for the perturbations and describe the behavior of the solutions in the low and high-frequency limits. We conclude by describing this phenomenology in the context of two screening mechanisms, chameleon and symmetron, and show that scalar waves in every frequency range are screened, hence not detectable.

Wormholes & Holography: An Introduction. (arXiv:2110.14958v1 [hep-th])

上午9:00 | | | gr-qc updates on arXiv.org |

Authors: Arnab Kundu

Wormholes are intriguing classical solutions in General Relativity, that have fascinated theoretical physicists for decades. In recent years, gravitational Wormhole geometries have found a new life in many theoretical ideas, especially in Holography. This is an introductory and pedagogical review of Wormholes and their recent applications in Gauge-Gravity duality and related ideas.

Can the displacemon device test objective collapse models?. (arXiv:2110.15180v1 [quant-ph])

上午9:00 | | | gr-qc updates on arXiv.org |

Authors: Lydia A. Kanari-Naish, Jack Clarke, Michael R. Vanner, Edward A. Laird

Testing the limits of the applicability of quantum mechanics will deepen our understanding of the universe and may shed light on the interplay between quantum mechanics and gravity. At present there is a wide range of approaches for such macroscopic tests spanning matter-wave interferometry of large molecules to precision measurements of heating rates in the motion of micro-scale cantilevers. The “displacemon” is a proposed electromechanical device consisting of a mechanical resonator flux coupled to a superconducting qubit, which could be used to generate and observe quantum interference between centre-of-mass trajectories in the motion of a resonator. In the original proposal, the mechanical resonator was a carbon nanotube, containing $10^6$ nucleons. Such a superposition would be massive by comparison to the present state-of-the-art, but still small compared with the mass scales on which we might feasibly test objective collapse models. Here, instead of a carbon nanotube, we propose using an aluminium mechanical resonator on two larger mass scales, one inspired by the Marshall-Simon-Penrose-Bouwmeester moving-mirror proposal, and one set by the Planck mass. For such a device, we examine the experimental requirements needed to perform a more macroscopic quantum test and thus feasibly detect the decoherence effects predicted by two objective collapse models: Di\'{o}si-Penrose and continuous spontaneous localization. Our protocol for testing these two theories takes advantage of the displacemon architecture by analyzing the measurement statistics of a superconducting qubit. We find that with improvements to the fabrication and vibration sensitivities of these electromechanical devices, the displacemon interferometer provides a new route to feasibly test decoherence mechanisms beyond standard quantum theory.

A “black hole theorem,” and its implications. (arXiv:2110.10690v1 [hep-th] CROSS LISTED)

上午9:00 | | | gr-qc updates on arXiv.org |

Authors: Steven B. Giddings

A “black hole theorem” is stated, exhibiting the basic conflict of the information problem. This is formulated in a more general context than that of quantum field theory on a background, and is based on describing a black hole as a quantum subsystem of a larger system, including its environment. As with the Coleman-Mandula theorem, the most important point is probably the loophole in the “theorem,” and what this tells us about the fundamental structure of quantum gravity. This “theorem” in particular connects to the general question of how to define quantum subsystems in quantum gravity. If black holes do behave as quantum subsystems, at least to a good approximation, evolve unitarily, and do not leave remnants, the “theorem” implies the presence of interactions between a black hole and its environment that go beyond a description based on local quantum fields. These can be parameterized in a principled way, and with motivated additional assumptions indicate possible observational signatures, which can be investigated by electromagnetic or gravitational wave observations of black holes.

Experimental Validation of Fully Quantum Fluctuation Theorems Using Dynamic Bayesian Networks

2021年10月29日 星期五 下午6:00 | | | Kaonan Micadei, John P. S. Peterson, Alexandre M. Souza, Roberto S. Sarthour, Ivan S. Oliveira, Gabriel T. Landi, Roberto M. Serra, and Eric Lutz | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Kaonan Micadei, John P. S. Peterson, Alexandre M. Souza, Roberto S. Sarthour, Ivan S. Oliveira, Gabriel T. Landi, Roberto M. Serra, and Eric Lutz

Fluctuation theorems are fundamental extensions of the second law of thermodynamics for small systems. Their general validity arbitrarily far from equilibrium makes them invaluable in nonequilibrium physics. So far, experimental studies of quantum fluctuation relations do not account for quantum cor…

[Phys. Rev. Lett. 127, 180603] Published Fri Oct 29, 2021

Direct Characterization of Quantum Measurements Using Weak Values

2021年10月28日 星期四 下午6:00 | | | Liang Xu, Huichao Xu, Tao Jiang, Feixiang Xu, Kaimin Zheng, Ben Wang, Aonan Zhang, and Lijian Zhang | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Liang Xu, Huichao Xu, Tao Jiang, Feixiang Xu, Kaimin Zheng, Ben Wang, Aonan Zhang, and Lijian Zhang

The time-symmetric formalism endows the weak measurement and its outcome, the weak value, with many unique features. In particular, it allows a direct tomography of quantum states without resorting to complicated reconstruction algorithms and provides an operational meaning to wave functions and den…

[Phys. Rev. Lett. 127, 180401] Published Thu Oct 28, 2021

The role of representational conventions in assessing the empirical significance of symmetries

2021年10月28日 星期四 下午3:53 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gomes, Henrique (2021) The role of representational conventions in assessing the empirical significance of symmetries. [Preprint]

Gauge-invariance and the empirical significance of symmetries

2021年10月28日 星期四 下午3:53 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gomes, Henrique (2020) Gauge-invariance and the empirical significance of symmetries. [Preprint]

Scientific Realism and Empirical Confirmation: a Puzzle

2021年10月28日 星期四 下午3:52 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Allzén, Simon (2021) Scientific Realism and Empirical Confirmation: a Puzzle. Studies in History and Philosophy of Science Part A, 90. pp. 153-159. ISSN 00393681

Quantum States: An Analysis via the Orthogonality Relation

2021年10月28日 星期四 下午3:52 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Zhong, Shengyang (2021) Quantum States: An Analysis via the Orthogonality Relation. Synthese. ISSN 1573-0964

2021年10月28日 星期四 下午3:51 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Merritt, David (2021) MOND and Methodology. Karl Popper’s Science and Philosophy. pp. 69-96.

The Cost of Closure: Logical Realism, Anti-Exceptionalism, and Theoretical Equivalence

2021年10月26日 星期二 下午4:12 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

McSweeney, Michaela (2021) The Cost of Closure: Logical Realism, Anti-Exceptionalism, and Theoretical Equivalence. Synthese. ISSN 1573-0964

Quantum Conditional Probabilities and New Measures of Quantum Information

2021年10月26日 星期二 下午4:11 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Barandes, Jacob A. and Kagan, David (2021) Quantum Conditional Probabilities and New Measures of Quantum Information. [Preprint]

Jonathan Schonfeld

Using publically available video of a cloud chamber with a very small radioactive source, I measure the spatial distribution of where tracks start, and consider possible implications. This is directly relevant to the quantum measurement problem and its possible resolution, and appears never to have been done before. The raw data are relatively uncontrolled, leading to caveats that should guide future, more tailored experiments. Results suggest a modification to Born’s rule at very small wavefunction. Track distributions from decays in cloud chambers represent a previously unappreciated way to probe the foundations of quantum mechanics, and a novel case of wavefunctions with macroscopic signatures.

]]>I hope that these two new results presented in | arXiv:1805.03952v12 |

will be interesting:

I have found that the process of scattering a particle on a one-dimensional delta-potential (and any other short-range potential) is closely related to the thought experiment “Einstein’s Boxes”. I presented a new view on this experiment. The main feature of this view is that this experiment is directed not only against the doctrine of incompleteness of quantum mechanics (as Einstein thought), but also against the superposition principle in those one-particle problems where “Einstein’s Boxes” arise. The scattering process under study belongs to this class of problems. In this case the quantum one-particle dynamics loses the uniqueness property in the limits t→∞ and, hence, ceases to be unitary. Thus, the formal Hamiltonian with the delta-potential (and with any other short-range potential) has no everywhere dense domain, in the Hilbert space, where it would be defined as a linear operator. This means that this scattering process is a “mixture” of two co-developing sub-processes – transmission and reflection. Because of the interference between them, both at the initial stage of scattering and at the very stage of scattering, only an indirect measurement of the physical quantities of each subprocess is possible. A model is presented to describe these sub-processes at all stages of scattering.

It is also shown that the generally accepted point of view, according to which “To know the quantum mechanical state of a system implies, in general, only statistical restrictions on the results of measurements”, is fundamentally wrong. I show that even the squared modulus of the wave function imposes more than just statistical restrictions on the state of a quantum ensemble (remind, within the incompleteness doctrine, quantum mechanics describes quantum ensembles). As regards the phase of the wave function, it has sets the momentum field of the quantum ensemble. That is, quantum mechanics not only does not prohibit the simultaneous measurement of the coordinate and momentum of a particle, but yet predicts the value of the momentum at that spatial point where the particle will (accidentally) be detected.

]]>上午10:17 | | | L.I. Rozonoer | | | quant-ph updates on arXiv.org |

The hypothesis of the random flow of time is considered. To do this, the concepts of microscopic random time and macroscopic mean time, as well as random modular time are introduced. The possibilities of experimental verification of the hypothesis of the random flow of time are discussed.

Quantumness Beyond Entanglement: The Case of Symmetric States. (arXiv:2110.11361v1 [quant-ph])

上午10:17 | | | Aaron Z. Goldberg, Markus Grassl, Gerd Leuchs, Luis L. Sánchez-Soto | | | quant-ph updates on arXiv.org |

It is nowadays accepted that truly quantum correlations can exist even in the absence of entanglement. For the case of symmetric states, a physically trivial unitary transformation can alter a quantum state from entangled to separable and vice versa. We propose to certify the presence of quantumness via an average over all physically relevant modal decompositions. We investigate extremal states for such a measure: SU(2)-coherent states possess the least quantumness whereas the opposite extreme is inhabited by states with maximally spread Majorana constellations.

Topological Insulators Quantum Mechanics. (arXiv:2110.11455v1 [hep-th])

上午10:17 | | | J. Gamboa, F. Mendez | | | quant-ph updates on arXiv.org |

Topological insulators in three dimensions are studied as a problem of supersymmetric quantum mechanics. The spin-orbit coupling is induced as a consequence of the supersymmetrization procedure and we show that it is equivalent to the appearance of a $SU(2)$ connection. The procedure presented in this letter is general and valid for any three-dimensional quantum system. The approach allows — in principle — to study a wide range of topological insulators as standard quantum mechanical problems. As an illustration the three-dimensional harmonic oscillator and the Aharonov-Bohm effect are studied in detail.

The Cosmic Void. (arXiv:2110.11859v1 [physics.hist-ph])

上午10:17 | | | physics.hist-ph updates on arXiv.org |

Authors: Eddy Keming Chen

What exists at the fundamental level of reality? On the standard picture, the fundamental reality contains (among other things) fundamental matter, such as particles, fields, or even the quantum state. Non-fundamental facts are explained by facts about fundamental matter, at least in part. In this paper, I introduce a non-standard picture called the “cosmic void” in which the universe is devoid of any fundamental material ontology. Facts about tables and chairs are recovered from a special kind of laws that satisfy strong determinism. All non-fundamental facts are completely explained by nomic facts. I discuss a concrete example of this picture in a strongly deterministic version of the many-worlds theory of quantum mechanics. I discuss some philosophical and scientific challenges to this view, as well as some connections to ontological nihilism.

Interdimensionality. (arXiv:2110.11394v1 [physics.gen-ph])

上午10:17 | | | gr-qc updates on arXiv.org |

Authors: Karl Svozil

In this speculative analysis, interdimensionality is introduced as the (co)existence of universes embedded into larger ones. These interdimensional universes may be isolated or intertwined, suggesting a variety of interdimensional intrinsic phenomena that can only be understood in terms of the outer, extrinsic reality.

上午10:17 | | | gr-qc updates on arXiv.org |

Authors: S. Nesseris, D. Sapone, M. Martinelli, D. Camarena, V. Marra, Z. Sakr, J. Garcia-Bellido, C.J.A.P. Martins, C. Clarkson, A. Da Silva, P. Fleury, L. Lombriser, J.P. Mimoso, S. Casas, V. Pettorino, I. Tutusaus, A. Amara, N. Auricchio, C. Bodendorf, D. Bonino, E. Branchini, M. Brescia, V. Capobianco, C. Carbone, J. Carretero, M. Castellano, S. Cavuoti, A. Cimatti, R. Cledassou, G. Congedo, L. Conversi, Y. Copin, L. Corcione, F. Courbin, M. Cropper, H. Degaudenzi, M. Douspis, F. Dubath, C.A.J. Duncan, X. Dupac, S. Dusini, A. Ealet, S. Farrens, P. Fosalba, M. Frailis, E. Franceschi, M. Fumana, B. Garilli, B. Gillis, C. Giocoli, A. Grazian, F. Grupp, S.V.H. Haugan, W. Holmes, F. Hormuth, K. Jahnke, S. Kermiche, A. Kiessling, T. Kitching, M. Kümmel, M. Kunz, H. Kurki-Suonio, S. Ligori, P.B. Lilje, et al. (51 additional authors not shown)

The standard cosmological model is based on the simplifying assumptions of a spatially homogeneous and isotropic universe on large scales. An observational detection of their violation, at any redshift, would immediately indicate the breakdown of the aforementioned assumptions or presence of new physics. We quantify the ability of the Euclid mission, together with contemporary surveys, to improve the current sensitivity of null tests of the canonical cosmological constant and cold dark matter (LCDM) model, in the redshift range $0<z<1.8$. We consider both currently available data and simulated Euclid and external data products based on a LCDM fiducial model, an evolving dark energy model assuming the Chevallier-Polarski-Linder (CPL) parametrization or an inhomogeneous Lema\^{\i}tre-Tolman-Bondi model with a cosmological constant (LLTB), and carry out two separate, albeit complementary, analyses: a machine learning reconstruction based on genetic algorithms and a theory-agnostic parametric approach based on polynomial reconstruction and binning of the data, in order not to make assumptions about any particular model. We find that using the machine learning approach Euclid can (in combination with external probes) improve current constraints on null tests of the LCDM by approximately a factor of two to three, while in the case of the binning approach, Euclid can provide tighter constraints than the genetic algorithms by a further factor of two in the case of the LCDM mock, albeit in certain cases may be biased against or missing some features of models far from LCDM, as is the case with the CPL and LLTB mocks. Our analysis highlights the importance of synergies between Euclid and other surveys, which are crucial to provide tighter constraints over an extended redshift range, for a plethora of different consistency tests of some of the main assumptions of the current cosmological paradigm.

Idealizations and analogies: Explaining critical phenomena

2021年10月24日 星期日 下午3:43 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Rodriguez, Quentin (2021) Idealizations and analogies: Explaining critical phenomena. Studies in History and Philosophy of Science Part A, 89. pp. 235-247. ISSN 00393681

The Quantum Revolution in Philosophy (Book Review)

2021年10月24日 星期日 下午3:42 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Chen, Eddy Keming (2020) The Quantum Revolution in Philosophy (Book Review). The Philosophical Review, 129 (2). pp. 302-308.

Time’s Arrow and Self-Locating Probability

2021年10月24日 星期日 下午3:41 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Chen, Eddy Keming (2021) Time’s Arrow and Self-Locating Probability. Philosophy and Phenomenological Research.

How to Choose a Gauge? The case of Hamiltonian Electromagnetism

2021年10月24日 星期日 下午3:40 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gomes, Henrique and Butterfield, Jeremy (2021) How to Choose a Gauge? The case of Hamiltonian Electromagnetism. [Preprint]

Isolated systems and their symmetries, part II: local and global symmetries of field theories

2021年10月24日 星期日 下午3:39 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Wallace, David (2021) Isolated systems and their symmetries, part II: local and global symmetries of field theories. [Preprint]

Isolated Systems and their Symmetries, Part I: General Framework and Particle-Mechanics Examples

2021年10月24日 星期日 下午3:39 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Wallace, David (2021) Isolated Systems and their Symmetries, Part I: General Framework and Particle-Mechanics Examples. [Preprint]

Quasi-set theory for a quantum ontology of properties

2021年10月24日 星期日 下午3:38 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Holik, Federico and Jorge, Juan Pablo and Krause, Décio and Lombardi, Olimpia (2021) Quasi-set theory for a quantum ontology of properties. [Preprint]

Our Fundamental Physical Space: An Essay on the Metaphysics of the Wave Function

2021年10月24日 星期日 上午5:59 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Chen, Eddy Keming (2017) Our Fundamental Physical Space: An Essay on the Metaphysics of the Wave Function. The Journal of Philosophy, 114 (7). pp. 333-365. ISSN 0022-362X

Quantum Mechanics Without Indeterminacy

2021年10月22日 星期五 下午4:25 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Glick, David (2021) Quantum Mechanics Without Indeterminacy. [Preprint]

Weak-Measurement-Induced Asymmetric Dephasing: Manifestation of Intrinsic Measurement Chirality

2021年10月18日 星期一 下午6:00 | | | Kyrylo Snizhko, Parveen Kumar, Nihal Rao, and Yuval Gefen | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Kyrylo Snizhko, Parveen Kumar, Nihal Rao, and Yuval Gefen

Geometrical dephasing is distinct from dynamical dephasing in that it depends on the trajectory traversed, hence it reverses its sign upon flipping the direction in which the path is traced. Here we study sequences of generalized (weak) measurements that steer a system in a closed trajectory. The re…

[Phys. Rev. Lett. 127, 170401] Published Mon Oct 18, 2021

]]>2021年10月16日 星期六 上午11:02 | | | Roman Stricker, Davide Vodola, Alexander Erhard, Lukas Postler, Michael Meth, Martin Ringbauer, Philipp Schindler, Rainer Blatt, Markus Müller, Thomas Monz | | | quant-ph updates on arXiv.org |

In quantum information processing quantum operations are often processed alongside measurements which result in classical data. Due to the information gain of classical measurement outputs non-unitary dynamical processes can take place on the system, for which common quantum channel descriptions fail to describe the time evolution. Quantum measurements are correctly treated by means of so-called quantum instruments capturing both classical outputs and post-measurement quantum states. Here we present a general recipe to characterize quantum instruments alongside its experimental implementation and analysis. Thereby, the full dynamics of a quantum instrument can be captured, exhibiting details of the quantum dynamics that would be overlooked with common tomography techniques. For illustration, we apply our characterization technique to a quantum instrument used for the detection of qubit loss and leakage, which was recently implemented as a building block in a quantum error correction (QEC) experiment (Nature 585, 207-210 (2020)). Our analysis reveals unexpected and in-depth information about the failure modes of the implementation of the quantum instrument. We then numerically study the implications of these experimental failure modes on QEC performance, when the instrument is employed as a building block in QEC protocols on a logical qubit. Our results highlight the importance of careful characterization and modelling of failure modes in quantum instruments, as compared to simplistic hardware-agnostic phenomenological noise models, which fail to predict the undesired behavior of faulty quantum instruments. The presented methods and results are directly applicable to generic quantum instruments.

Coherent energy fluctuation theorems: theory and experiment. (arXiv:2110.07061v1 [quant-ph])

2021年10月16日 星期六 上午11:02 | | | K. Khan, J. Sales Araújo, W. F. Magalhães, G. H. Aguilar, B. de Lima Bernardo | | | quant-ph updates on arXiv.org |

Heat, work and entropy production: the statistical distribution of such quantities are constrained by the fluctuation theorems (FT), which reveal crucial properties about the nature of non-equilibrium dynamics. In this paper we report theoretical and experimental results regarding two FT for a new quantity, named coherent energy, which is an energy form directly associated with the coherences of the quantum state. We also demonstrate that this quantity behaves as a thermodynamic arrow of time for unitary evolutions, that is, in the absence of entropy production. The experiment is implemented in an all-optical setup in which the system is encoded in the polarization of one photon of a pair. The FT are demonstrated using the two-point measurement protocol, executed using the other photon of the pair, allowing to assess the probability distributions directly from the outcomes of the experiment.

2021年10月16日 星期六 上午11:02 | | | Stefano Gogioso | | | quant-ph updates on arXiv.org |

We use purity, a principle borrowed from the foundations of quantum information, to show that all special symmetric $\dagger$-Frobenius algebras in $\operatorname{CPM}\left(\operatorname{fHilb}\right)$ — and, in particular, all classical structures — are canonical, i.e. that they arise by doubling of special symmetric $\dagger$-Frobenius algebras in $\operatorname{fHilb}$. This provides an exact classification of finite-dimensional quantum observables.

Physical mechanisms underpinning the vacuum permittivity. (arXiv:2110.07223v1 [quant-ph])

2021年10月16日 星期六 上午11:02 | | | Gerd Leuchs, Margaret Hawton, Luis L. Sanchez-Soto | | | quant-ph updates on arXiv.org |

Debate about the emptiness of the space goes back to the prehistory of science and is epitomized by the Aristotelian \emph{horror vacui}, which can be seen as the precursor of the ether, whose modern version is the dynamical quantum vacuum. Here, we change our view to \emph{gaudium vacui} and discuss how the vacuum fluctuations fix the value of the permittivity $\varepsilon_{0}$ and permeability $\mu_{0}$.

2021年10月16日 星期六 上午11:02 | | | E. Alex Wollack, Agnetta Y. Cleland, Rachel G. Gruenke, Zhaoyou Wang, Patricio Arrangoiz-Arriola, Amir H. Safavi-Naeini | | | quant-ph updates on arXiv.org |

Precisely engineered mechanical oscillators keep time, filter signals, and sense motion, making them an indispensable part of today’s technological landscape. These unique capabilities motivate bringing mechanical devices into the quantum domain by interfacing them with engineered quantum circuits. Proposals to combine microwave-frequency mechanical resonators with superconducting devices suggest the possibility of powerful quantum acoustic processors. Meanwhile, experiments in several mechanical systems have demonstrated quantum state control and readout, phonon number resolution, and phonon-mediated qubit-qubit interactions. Currently, these acoustic platforms lack processors capable of controlling multiple mechanical oscillators’ quantum states with a single qubit, and the rapid quantum non-demolition measurements of mechanical states needed for error correction. Here we use a superconducting qubit to control and read out the quantum state of a pair of nanomechanical resonators. Our device is capable of fast qubit-mechanics swap operations, which we use to deterministically manipulate the mechanical states. By placing the qubit into the strong dispersive regime with both mechanical resonators simultaneously, we determine the resonators’ phonon number distributions via Ramsey measurements. Finally, we present quantum tomography of the prepared nonclassical and entangled mechanical states. Our result represents a concrete step toward feedback-based operation of a quantum acoustic processor.

Why and whence the Hilbert space in quantum theory?. (arXiv:2110.05932v2 [physics.gen-ph] UPDATED)

2021年10月16日 星期六 上午11:02 | | | Yu. V. Brezhnev | | | quant-ph updates on arXiv.org |

We explain why and how the Hilbert space comes about in quantum theory. The axiomatic structures of a vector space, of scalar product, of orthogonality, and of the linear functional are derivable from the statistical description of quantum micro-events and from Hilbertian sum of squares $|\mathfrak{a}_1|^2+|\mathfrak{a}_2|^2+\cdots$. The latter leads (non-axiomatically) to the standard writing of the Born formula $\mathtt{f}=|\langle\psi|\varphi\rangle|^2$. As a corollary, the status of Pythagorean theorem, the concept of a length, and the 6-th Hilbert problem undergo a quantum `revision’. An issue of deriving the normed topology is likely solvable in the affirmative and has been stated as a mathematical problem.

2021年10月16日 星期六 上午11:02 | | | physics.hist-ph updates on arXiv.org |

Authors: Badis Ydri

In this essay a quantum-dualistic, perspectival and synchronistic interpretation of quantum mechanics is further developed in which the classical world-from-decoherence which is perceived (decoherence) and the perceived world-in-consciousness which is classical (collapse) are not necessarily identified. Thus, Quantum Reality or “{\it unus mundus}” is seen as both i) a physical non-perspectival causal Reality where the quantum-to-classical transition is operated by decoherence, and as ii) a quantum linear superposition of all classical psycho-physical perspectival Realities which are governed by synchronicity as well as causality (corresponding to classical first-person observes who actually populate the world). This interpretation is termed the Nietzsche-Jung-Pauli interpretation and is a re-imagining of the Wigner-von Neumann interpretation which is also consistent with some reading of Bohr’s quantum philosophy.

2021年10月16日 星期六 上午11:02 | | | physics.hist-ph updates on arXiv.org |

Authors: W.M. Stuckey, Timothy McDevitt, Michael Silberstein

We review how the kinematic structures of special relativity and quantum mechanics both stem from the relativity principle, i.e., “no preferred reference frame” (NPRF). Essentially, NPRF applied to the measurement of the speed of light $c$ gives the light postulate and leads to the geometry of Minkowski spacetime, while NPRF applied to the measurement of Planck’s constant $h$ gives “average-only” projection and leads to the denumerable-dimensional Hilbert space of quantum mechanics. These kinematic structures contain the counterintuitive aspects (“mysteries”) of time dilation, length contraction, and quantum entanglement. In this essay, we extend the application of NPRF to the gravitational constant $G$ and show that it leads to the “mystery” of the contextuality of mass in general relativity. Thus, we see an underlying coherence and integrity in modern physics via its “mysteries” and the fundamental constants $c$, $h$, and $G$.

2021年10月16日 星期六 上午11:02 | | | physics.hist-ph updates on arXiv.org |

Authors: Henrique Gomes

The following questions are germane to our understanding of gauge-(in)variant quantities and physical possibility: in which ways are gauge transformations and spacetime diffeomorphisms similar, and in which are they different? To what extent are we justified in endorsing different attitudes — sophistication, quidditism/haecceitism, or full elimination — towards each? In a companion paper, I assess new and old contrasts between the two types of symmetries. In this one, I propose a new contrast: whether the symmetry changes pointwise the dynamical properties of a given field. This contrast distinguishes states that are related by a gauge-symmetry from states related by generic spacetime diffeomorphisms, as being `pointwise dynamically indiscernible’. Only the rigid isometries of homogeneous spacetimes fall in the same category, but they are neither local nor modally robust, in the way that gauge transformations are. In spite of this difference, I argue that for both gauge transformations and spacetime diffeomorphisms, symmetry-related models are best understood through the doctrine of `sophistication’.

2021年10月16日 星期六 上午11:02 | | | physics.hist-ph updates on arXiv.org |

Authors: Henrique Gomes

How should we understand gauge-(in)variant quantities and physical possibility? Does the redundancy present in gauge theory pose different interpretational issues than those present in general relativity? Here, I will assess new and old contrasts between general relativity and Yang-Mills theory, in particular, in relation to their symmetries. I will focus these comparisons on four topics: (i) non-locality, (ii) conserved charges, (iii) Aharonov-Bohm effect, and (iv) the choice of representational conventions of the field configuration. In a companion paper, I propose a new contrast and defend sophistication for both theories.

2021年10月16日 星期六 上午11:02 | | | physics.hist-ph updates on arXiv.org |

Authors: Henrique Gomes

A fundamental tenet of gauge theory is that physical quantities should be gauge-invariant. This prompts the question: can gauge symmetries have physical significance? On one hand, the Noether theorems relate conserved charges to symmetries, endowing the latter with physical significance, though this significance is sometimes taken as indirect. But for theories in spatially finite and bounded regions, the standard Noether charges are not gauge-invariant. I here argue that gauge-\emph{variance} of charges is tied to the nature of the non-locality within gauge theories. I will flesh out these links by providing a chain of (local) implications: `local conservation laws’${\Rightarrow}$ `conserved regional charges’ $\Leftrightarrow$ `non-separability’ ${\Leftrightarrow}$ `direct empirical significance of symmetries’.

An Algebraic Approach to Physical Fields. (arXiv:2108.07184v2 [physics.hist-ph] UPDATED)

2021年10月16日 星期六 上午11:02 | | | physics.hist-ph updates on arXiv.org |

Authors: Lu Chen, Tobias Fritz

According to the algebraic approach to spacetime, a thoroughgoing dynamicism, physical fields exist without an underlying manifold. This view is usually implemented by postulating an algebraic structure (e.g., commutative ring) of scalar-valued functions, which can be interpreted as representing a scalar field, and deriving other structures from it. In this work, we point out that this leads to the unjustified primacy of an undetermined scalar field. Instead, we propose to consider algebraic structures in which all (and only) physical fields are primitive. We explain how the theory of \emph{natural operations} in differential geometry — the modern formalism behind classifying diffeomorphism-invariant constructions — can be used to obtain concrete implementations of this idea for any given collection of fields.

For concrete examples, we illustrate how our approach applies to a number of particular physical fields, including electrodynamics coupled to a Weyl spinor.

Lessons from the information paradox

2021年10月16日 星期六 上午11:02 | | | 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 October 2021

**Source:** Physics Reports

Author(s): Suvrat Raju

Light, delayed: The Shapiro Effect and the Newtonian Limit. (arXiv:2110.07016v1 [gr-qc])

2021年10月16日 星期六 上午11:02 | | | gr-qc updates on arXiv.org |

Authors: Markus Pössel

The Shapiro effect, also known as the gravitational time delay, is close kin to the gravitational deflection of light that was the central topic of our Summer School. It is also an interesting test bed for exploring a topic that provides the foundations for most of the calculations we have done in this school, yet is highly complex when treated more rigorously: the question of the Newtonian limit, and of the post-Newtonian corrections that must be applied to include the leading-order effects of general relativity. This contribution discusses simplified derivations for the gravitational redshift and the Shapiro effect, as well as astrophysical situations in which the Shapiro effect can be measured.

2021年10月16日 星期六 上午11:02 | | | gr-qc updates on arXiv.org |

Authors: Sylvain Carrozza, Philipp A. Hoehn

We introduce a general framework realizing edge modes in (classical) gauge field theory as dynamical reference frames, an often suggested interpretation that we make entirely explicit. We focus on a bounded region $M$ with a co-dimension one time-like boundary $\Gamma$, which we embed in a global spacetime. Taking as input a variational principle at the global level, we develop a systematic formalism inducing consistent variational principles (and in particular, boundary actions) for the subregion $M$. This relies on a post-selection procedure on $\Gamma$, which isolates the subsector of the global theory compatible with a general choice of gauge-invariant boundary conditions for the dynamics in $M$. Crucially, the latter relate the configuration fields on $\Gamma$ to a dynamical frame field carrying information about the spacetime complement of $M$; as such, they may be equivalently interpreted as frame-dressed or relational observables. Generically, the external frame field keeps an imprint on the ensuing dynamics for subregion $M$, where it materializes itself as a local field on the time-like boundary $\Gamma$; in other words, an edge mode. We identify boundary symmetries as frame reorientations and show that they divide into three types, depending on the boundary conditions, that affect the physical status of the edge modes. Our construction relies on the covariant phase space formalism, and is in principle applicable to any gauge (field) theory. We illustrate it on three standard examples: Maxwell, Abelian Chern-Simons and non-Abelian Yang-Mills theories. In complement, we also analyze a mechanical toy-model to connect our work with recent efforts on (quantum) reference frames.

2021年10月14日 星期四 下午1:25 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

French, Steven (2021) Fundamentality. [Preprint]

2021年10月14日 星期四 下午1:22 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Merritt, David (2020) Cosmological Realism. [Preprint]

Neither Contextuality nor Nonlocality Admits Catalysts

2021年10月13日 星期三 下午6:00 | | | Martti Karvonen | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Martti Karvonen

We show that the resource theory of contextuality does not admit catalysts, i.e., there are no correlations that can enable an otherwise impossible resource conversion and still be recovered afterward. As a corollary, we observe that the same holds for nonlocality. As entanglement allows for catalys…

[Phys. Rev. Lett. 127, 160402] Published Wed Oct 13, 2021

Anderson Localization of Composite Particles

2021年10月12日 星期二 下午6:00 | | | Fumika Suzuki, Mikhail Lemeshko, Wojciech H. Zurek, and Roman V. Krems | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Fumika Suzuki, Mikhail Lemeshko, Wojciech H. Zurek, and Roman V. Krems

We investigate the effect of coupling between translational and internal degrees of freedom of composite quantum particles on their localization in a random potential. We show that entanglement between the two degrees of freedom weakens localization due to the upper bound imposed on the inverse part…

[Phys. Rev. Lett. 127, 160602] Published Tue Oct 12, 2021

2021年10月11日 星期一 下午6:00 | | | Kohei Yoshimura and Sosuke Ito | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Kohei Yoshimura and Sosuke Ito

The thermodynamic uncertainty relation and speed limit provide fundamental bounds relating basic properties of chemical reaction networks and their diffusion coefficients.

[Phys. Rev. Lett. 127, 160601] Published Mon Oct 11, 2021

On the alleged extra-structures of quantum mechanics

2021年10月11日 星期一 下午3:45 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Romano, Davide (2021) On the alleged extra-structures of quantum mechanics. [Preprint]

]]>下午12:15 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Di Biagio, Andrea and Rovelli, Carlo (2021) Relational Quantum Mechanics is about Facts, not States: A reply to Pienaar and Brukner. [Preprint]

Trans-Planckian Philosophy of Cosmology

下午12:10 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Schneider, Mike D. (2021) Trans-Planckian Philosophy of Cosmology. [Preprint]

Mutually Unbiased Quantum Observables. (arXiv:2110.03099v1 [quant-ph])

上午9:44 | | | Stan Gudder | | | quant-ph updates on arXiv.org |

We begin by defining mutually unbiased (MU) observables on a finite dimensional Hilbert space. We also consider the more general concept of parts of MU observables. The relationships between MU observables, value-complementary observables and two other conditions involving sequential products of observables are discussed. We next present a special motivating case of MU observables called finite position and momentum observables. These are atomic observables related by a finite Fourier transform. Finite position and momentum observables are employed to give examples of parts of MU observables that are value-complementary and those that are not value-complementary. Various open problems involving these concepts are presented. These problems mainly involve extending this work from sharp observables to unsharp observables.

上午9:44 | | | Masanao Ozawa | | | quant-ph updates on arXiv.org |

In this paper, we present a general theory of finite quantum measurements, for which we assume that the state space of the measured system is a finite dimensional Hilbert space and that the possible outcomes of a measurement is a finite set of the real numbers. We develop the theory in a deductive manner from the basic postulates for quantum mechanics and a few plausible axioms for general quantum measurements. We derive an axiomatic characterization of all the physically realizable finite quantum measurements. Mathematical tools necessary to describe measurement statistics, such as POVMs and quantum instruments, are not assumed at the outset, but we introduce them as natural consequences of our axioms. Our objective is to show that those mathematical tools can be naturally derived from obvious theoretical requirements.

From Classical to quantum stochastic process. (arXiv:2110.03668v1 [cond-mat.stat-mech])

上午9:44 | | | Gustavo Montes, Soham Biswas, Thomas Gorin | | | quant-ph updates on arXiv.org |

We construct quantum analogs of classical stochastic processes, by replacing random “which path” decisions with superposition of all paths. This procedure typically leads to non-unitary quantum evolution, where coherences are continuously generated and destroyed. In spite of their transient nature, these coherences can change the scaling behavior of classical observables. Using the zero temperature Glauber dynamics in a linear Ising spin chain, we find quantum analogs with different domain growth exponents. In some cases, this exponent is even smaller than for the original classical process, which means that coherence can lead to an important speed up the relaxation process.

上午9:44 | | | Eiji Konishi | | | quant-ph updates on arXiv.org |

We derive the projection hypothesis in projective quantum measurement by restricting the set of observables. This projection hypothesis accompanies a bipartite system with the von Neumann-type interaction, which consists of a quantum mechanical system, with a meter variable to be measured, and a quantum field theoretically macroscopic extended object, that is, a spatiotemporally inhomogeneous Bose-Einstein condensate in quantum field theory with the quantum coordinate, that is, the zero-energy Goldstone mode(s) of the spontaneously broken global spatial translational symmetry. The key steps in the derivation are the return of the symmetry translation of this quantum coordinate to the inverse translation of the c-number spatial coordinate in quantum field theory and the reduction of quantum fluctuations to classical fluctuations with respect to the Goldstone mode(s) due to a superselection rule.

上午9:44 | | | Justin K. Perron, Charles DeLeone, Shahed Sharif, Tom Carter, Joshua M. Grossman, Gina Passante, Joshua Sack | | | quant-ph updates on arXiv.org |

Currently, education and workforce training in quantum information science and technology (QIST) exists primarily at the graduate and postdoctoral levels, with few undergraduate efforts beginning to grow out of these. In order to meet the anticipated quantum workforce needs and to ensure that the workforce is demographically representative and inclusive to all communities, the United States must expand these efforts at the undergraduate level beyond what is occurring at larger PhD granting institutions and incorporate quantum information science into the curriculum at the nation’s predominantly undergraduate institutions (PUIs). On June 3rd and 4th, 2021 the Quantum Undergraduate Education and Scientific Training (QUEST) workshop was held virtually with the goal of bringing together faculty from PUIs to learn the state of undergraduate QIST education, identify challenges associated with implementing QIST curriculum at PUIs, and to develop strategies and solutions to deal with these challenges. This manuscript summarizes the results of workshop discussions with the hope of assisting faculty at PUIs attempting to incorporate quantum information science into their curriculum.

上午9:44 | | | Francesco Coradeschi, Antonia Micol Frassino, Thiago Guerreiro, Jennifer Rittenhouse West, Enrico Junior Schioppa | | | quant-ph updates on arXiv.org |

A theoretical framework for the quantization of gravity has been an elusive Holy Grail since the birth of quantum theory and general relativity. While generations of scientists have attempted solutions to this deep riddle, an alternative path built upon the idea that experimental evidence could determine whether gravity is quantized has been decades in the making. The possibility of an experimental answer to the question of the quantization of gravity is of renewed interest in the era of gravitational wave detectors. We review and investigate an important subset of phenomenological quantum gravity, detecting quantum signatures of weak gravitational fields in table-top experiments and interferometers.

The Life and Science of Thanu Padmanabhan. (arXiv:2110.03208v1 [physics.hist-ph])

上午9:44 | | | physics.hist-ph updates on arXiv.org |

Authors: Jasjeet Singh Bagla, Krishnakanta Bhattacharya, Sumanta Chakraborty, Sunu Engineer, Valerio Faraoni, Sanved Kolekar, Dawood Kothawala, Kinjalk Lochan, Sujoy Modak, V. Parameswaran Nair, Aseem Paranjape, Krishnamohan Parattu, Sarada G. Rajeev, Bibhas Ranjan Majhi, Tirthankar Roy Choudhury, Mohammad Sami, Sudipta Sarkar, Sandipan Sengupta, T. R. Seshadri, S. Shankaranarayanan, Suprit Singh, Tejinder P. Singh, L. Sriramkumar, Urjit Yajnik

Thanu Padmanabhan was a renowned Indian theoretical physicist known for his research in general relativity, cosmology, and quantum gravity. In an extraordinary career spanning forty-two years, he published more than three hundred research articles, wrote ten highly successful technical and popular books, and mentored nearly thirty graduate students and post-doctoral fellows. He is best known for his deep work investigating gravitation as an emergent thermodynamic phenomenon. He was an outstanding teacher, and an indefatigable populariser of science, who travelled very widely to motivate and inspire young students. Paddy, as he was affectionately known, was also a close friend to his students and collaborators, treating them as part of his extended academic family. On September 17, 2021 Paddy passed away very unexpectedly, at the age of sixty-four and at the height of his research career, while serving as a Distinguished Professor at the Inter-University Centre for Astronomy and Astrophysics, Pune. His untimely demise has come as a shock to his family and friends and colleagues. In this article, several of them have come together to pay their tributes and share their fond memories of Paddy.

Probability distribution for the quantum universe. (arXiv:2110.03050v1 [hep-th])

上午9:43 | | | gr-qc updates on arXiv.org |

Authors: Alex Kehagias, Hervé Partouche, Nicolaos Toumbas

We determine the inner product on the Hilbert space of wavefunctions of the universe by imposing the Hermiticity of the quantum Hamiltonian in the context of the minisuperspace model. The corresponding quantum probability density reproduces successfully the classical probability distribution in the $\hbar \to 0$ limit, for closed universes filled with a perfect fluid of index $w$. When $-1/3<w\le 1$, the wavefunction is normalizable and the quantum probability density becomes vanishingly small at the big bang/big crunch singularities, at least at the semi-classical level. Quantum expectation values of physical geometrical quantities, which diverge classically at the singularities, are shown to be finite.

上午9:43 | | | gr-qc updates on arXiv.org |

Authors: Gabriel Leuenberger

The causal set program as well as the Wolfram physics project leave open the problem of how a graph that is a (3+1)-dimensional Minkowski-spacetime according to its simple geodesic distances, could be generated solely from simple deterministic rules. This paper provides a solution by describing simple rules that characterize discrete Lorentz boosts between 4D lattice graphs, which combine further to form Wigner rotations that produce isotropy and lead to the emergence of the continuous Lorentz group and the (3+1)-dimensional Minkowski-spacetime. On such graphs, the speed of light, the proper time interval, as well as the proper length are all shown to be highly accurate.

上午9:43 | | | gr-qc updates on arXiv.org |

Authors: George Alestas, Ioannis Antoniou, Leandros Perivolaropoulos

We use an up to date compilation of Tully-Fisher data to search for transitions in the evolution of the Tully-Fisher relation. Using an up to date data compilation, we find hints at $\approx 3\sigma$ level for a transition at critical distances $D_c \simeq 9 Mpc$ and $D_c \simeq 17 Mpc$. We split the full sample in two subsamples according to the measured galaxy distance with respect to a splitting distance $D_c$ and identify the likelihood of the best fit slope and intercept of one sample with respect to the best fit corresponding values of the other sample. For $D_c \simeq 9 Mpc$ and $D_c \simeq 17 Mpc$ we find a tension between the two subsamples at a level of $\Delta \chi^2 > 17\; (3.5\sigma)$. Using a Monte-Carlo simulation we demonstrate that this result is robust with respect to random statistical and systematic variations of the galactic distances. If the tension is interpreted as due to a gravitational strength transition, it would imply a shift of the effective gravitational constant to lower values for distances larger than $D_c$ by $\frac{\Delta G}{G}\simeq -0.1$. Such a shift is of the anticipated sign and magnitude but at somewhat lower distance (redshift) than the gravitational transition recently proposed to address the Hubble and growth tensions ($\frac{\Delta G}{G}\simeq -0.1$ at transition redshift $z_t\lesssim 0.01$ ($D_c\lesssim 40 Mpc$)).

Carroll symmetry, dark energy and inflation. (arXiv:2110.02319v1 [hep-th] CROSS LISTED)

上午9:43 | | | gr-qc updates on arXiv.org |

Authors: Jan de Boer, Jelle Hartong, Niels A. Obers, Watse Sybesma, Stefan Vandoren

Carroll symmetry arises from Poincar\’e symmetry upon taking the limit of vanishing speed of light. We determine the constraints on the energy-momentum tensor implied by Carroll symmetry and show that for energy-momentum tensors of perfect fluid form, these imply an equation of state ${\cal E}+P=0$ for energy density plus pressure. Therefore Carroll symmetry might be relevant for dark energy and inflation. In the Carroll limit, the Hubble radius goes to zero and outside it recessional velocities are naturally large compared to the speed of light. The de Sitter group of isometries, after the limit, becomes the conformal group in Euclidean flat space. We also study the Carroll limit of chaotic inflation, and show that the scalar field is naturally driven to have an equation of state with $w=-1$. Finally we show that the freeze-out of scalar perturbations in the two point function at horizon crossing is a consequence of Carroll symmetry.

To make the paper self-contained, we include a brief pedagogical review of Carroll symmetry, Carroll particles and Carroll field theories that contains some new material as well. In particular we show, using an expansion around speed of light going to zero, that for scalar and Maxwell type theories one can take two different Carroll limits at the level of the action. In the Maxwell case these correspond to the electric and magnetic limit. For point particles we show that there are two types of Carroll particles: those that cannot move in space and particles that cannot stand still.

Analyzing Nonequilibrium Quantum States through Snapshots with Artificial Neural Networks

2021年10月7日 星期四 下午6:00 | | | A. Bohrdt, S. Kim, A. Lukin, M. Rispoli, R. Schittko, M. Knap, M. Greiner, and J. Léonard | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): A. Bohrdt, S. Kim, A. Lukin, M. Rispoli, R. Schittko, M. Knap, M. Greiner, and J. Léonard

Current quantum simulation experiments are starting to explore nonequilibrium many-body dynamics in previously inaccessible regimes in terms of system sizes and timescales. Therefore, the question emerges as to which observables are best suited to study the dynamics in such quantum many-body systems…

[Phys. Rev. Lett. 127, 150504] Published Thu Oct 07, 2021

The statistical interpretation: Born, Heisenberg and von Neumann, 1926-27

2021年10月7日 星期四 上午12:28 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Bacciagaluppi, Guido (2021) The statistical interpretation: Born, Heisenberg and von Neumann, 1926-27. [Preprint]

The Double Nature of Maxwell’s Physical Analogies

2021年10月7日 星期四 上午12:21 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Nappo, Francesco (2021) The Double Nature of Maxwell’s Physical Analogies. [Preprint]

2021年10月6日 星期三 上午8:00 | | | Leonardo Benini | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 06 October 2021; doi:10.1038/s41567-021-01389-8

The duality of a multitude

]]>Planck’s constant and the gravitational constant embody natural units of length, mass, and time. When we replace the universal constants with natural Planck units, a hidden structure appears in the equations of physics comprising ratios of length, mass, and time to the Planck scale. It is the proportions of Planck units that define observable physical phenomena and not the composite values of the constants. Natural unit formulas offer more granular information about the structure of matter and radiation than equations written with hbar and G. These natural formulas reveal physical relationships explaining the correspondence between classical and quantum phenomena. Relationships between rest mass, velocity, and wavelength show how classical and quantum mechanical momentum and energy are related, suggesting that momentum is universally a function of wavelength and not velocity.

]]>The mind-body problem is reviewed in the context of a non-technical account of quantum theory. The importance of clearly defining: `what is physical?’ is highlighted, since only then can we give meaning to the concept `non-physical’. Physicality is defined in terms of interaction, which is in turn defined to be a correlated exchange of information. This is asserted to be the basis of any meaningful concept of epistemology. Hence, it is argued that a non-physical entity can not `know’ anything about the world. Information transfer is then discussed in terms of quantum entanglement and an argument for our perception of time is presented. It is then contended that the notion of `mind’ may be meaningfully discussed in the context of a quantum theoretic framework.

]]>In a recent series of papers and lectures, John Conway and Simon Kochen presented The Free Will Theorem. “It asserts, roughly, that if indeed we humans have free will, then elementary particles already have their own small share of this valuable commodity.” Perhaps the primary motivation of their papers was to place stringent constraints on quantum mechanical hidden variable theories, which they indeed do. Nevertheless, the notion of free will is crucial to the proof and they even speculate that the free will afforded to elementary particles is the ultimate explanation of our own free will. I don’t challenge the mathematics/logic of their proof but rather their premises. Free will and determinism are, for me, not nearly adequately clarified for them to form the bases of a theoretical proof. In addition, they take for granted supplemental concepts in quantum mechanics that are in need of further explanation. It’s also not clear to me what utility is afforded by the free will theorem, i.e., what, if anything, follows from it. Despite the cheeky subtitle of my essay, I do think that the explicit introduction of free will into discussions of hidden variables and other interpretations of quantum mechanics might help expose foibles in many of those deliberations. For this reason, I consider the Conway-Kochen free will theorem to be a positive contribution to the philosophy of quantum mechanics.

]]>