| 上午9:21 | | | Yu Wang | | | quant-ph updates on arXiv.org |
The position and momentum distributions play an important role in the determination of classical and quantum states, which reveals a fundamental gap between classical and quantum world. For finite dimensional quantum system, a particle moving in one spatial dimension is expressed as a pure quantum state and projective measurements onto two special orthonormal bases are regarded as the observations of position and momentum, which are not enough for the uniquely determination of pure qudit states. In this paper, we focus on the determination of all finite dimensional pure quantum states with projective measurements onto two orthonormal bases. Firstly, a new orthonormal basis is constructed for the replacement of discrete analogy of momentum, which can help to filter out finite candidates among all pure qudit states with probability 1. Then, the analogy bases for position and momentum are enough to determine almost all pure qudits when introducing an adaptive POVM.
| 上午9:21 | | | Ehtibar N. Dzhafarov | | | quant-ph updates on arXiv.org |
Traditional Bell criteria of contextuality/nonlocality can be derived without any falsifiable assumptions, such as context-independent mapping (or local causality), free choice, or no-fine-tuning. This is achieved by deriving Bell criteria for systems with disturbance, based on the generalized definition of contextuality in the Contextuality-by-Default approach, and then specializing these criteria to systems with no disturbance. Context-independent mapping and no-fine-tuning are derived rather than assumed, and free choice follows from context-independent mapping. KEYWORDS: Bell criteria; contextuality; context-independent mapping; free choice; local causality; no-fine-tuning; nonlocality.
| 上午9:21 | | | Alexey V. Veryaskin, Michael E. Tobar | | | quant-ph updates on arXiv.org |
The era of practical terrestrial applications of gravity gradiometry begun in 1890 when Baron Lorand von E\”otv\”os, a Hungarian nobleman and a talented physicist and engineer, invented his famous torsion balance – the first practical gravity gradients measuring device. It was credited for the major oil discoveries later in Texas (USA). A 100 years later Kasevich and Chu pioneered the use of quantum physics for gravity gradient measurements. Since then cold-atom gravity gradiometers, or matter-wave gravity gradiometers, had been under development at almost every physics department of top-rated universities around the globe. After another 30 years since the Kasevich and Chu publication in 1992, which had led to the first ever quantum gravity gradiometer, the corresponding research and development ceased from being profoundly active a few years back. This article is an attempt to understand and explain what may have happened to the Quantum Invasion into the area of applied physics and precision engineering that traditionally has been occupied by non-quantum technologies developed for about a 130 years of the history of gravity gradiometry.
| 上午9:21 | | | Ingita Banerjee, Kornikar Sen, Chirag Srivastava, Ujjwal Sen | | | quant-ph updates on arXiv.org |
Quantum coherence quantifies the amount of superposition in a quantum system, and is the reason and resource behind several phenomena and technologies. It depends on the natural basis in which the quantum state of the system is expressed, which in turn hinges on the physical set-up being analyzed and utilized. While quantum coherence has hitherto been conceptualized by employing different categories of complete bases, there do exist interesting physical situations, where the natural basis is an incomplete one, an example being an interferometric set-up with the observer controlling only a certain fraction of all the slits. We introduce a quantification of quantum coherence with respect to an arbitrary incomplete basis for general quantum states, and develop the corresponding resource theory, identifying the free states and operations. Moreover, we obtain a complementarity relation between the so-defined quantum coherence and the which-path information in an interferometric set-up with several slits, of which only a section is in control of the observer or is accessible to her. This therefore provides us with another face of the wave-particle duality in quantum systems, demonstrating that the complementarity is functional in more general set-ups than thus far considered.
On Complex numbers in Quantum Mechanics. (arXiv:2108.05715v1 [physics.gen-ph])
| 上午9:21 | | | Faical Barzi | | | quant-ph updates on arXiv.org |
We look at the fundamental use of complex numbers in Quantum Mechanics (QM). A review of some of the most popular reasons given in the literature to support the necessity of the complex formalism, We add some insight by invoking others. This short study is aimed at strengthening the delicate pedagogical endeavor of explaining Why Quantum mechanics needs complex numbers
| 上午9:21 | | | Dong Jin Lee, Dong-han Yeom | | | quant-ph updates on arXiv.org |
In this paper, we critically revisit the Horowitz-Maldacena proposal and its generalization by Lloyd. In the original proposal, as well as in Lloyd’s generalization, Hawking radiation involves a pair of maximally entangled quantum states in which the ingoing partner state and the collapsed matter form either a maximally entangled pair or a Schmidt decomposed random state near the singularity. We point out that the unitary matrix introduced in Lloyd’s fidelity calculation depends on initial matter states; hence, his result on the high average fidelity may not represent an almost unitary evolution. In opposition to Lloyd’s conclusion, when we do not include the state-dependent unitary matrix for the fidelity computation, we analytically and numerically confirm that information will almost certainly be lost because the fidelity will approach zero as the degrees of freedom increase.
| 上午9:21 | | | physics.hist-ph updates on arXiv.org |
Authors: Tein van der Lugt
In recent publications in physics and mathematics, concerns have been raised about the use of real numbers to describe quantities in physics, and in particular about the usual assumption that physical quantities are infinitely precise. In this thesis, we discuss some motivations for dropping this assumption, which we believe partly arises from the usual point-based approach to the mathematical continuum. We focus on the case of classical mechanics specifically, but the ideas could be extended to other theories as well. We analyse the alternative theory of classical mechanics presented by Gisin and Del Santo, which suggests that physical quantities can equivalently be thought of as being only determined up to finite precision at each point in time, and that doing so naturally leads to indeterminism. Next, we investigate whether we can use intuitionistic mathematics to mathematically express the idea of finite precision of quantities, arriving at the cautious conclusion that, as far as we can see, such attempts are thwarted by conceptual contradictions. Finally, we outline another approach to formalising finite-precision quantities in classical mechanics, which is inspired by the intuitionistic approach to the continuum but uses classical mathematics.
Future Boundaries and the Black Hole Information Paradox. (arXiv:2108.05744v1 [hep-th])
| 上午9:21 | | | gr-qc updates on arXiv.org |
Authors: Malcolm J. Perry
The black hole information paradox is the incompatibility of quantum mechanics with the semi-classical picture of Hawking radiation. Hawking radiation appears thermal and eventually leads to the complete disappearance of a black hole. However, black holes could be formed from a pure quantum state. The transition from such an initial state to the final state of pure Hawking radiation cannot be described by unitary time evolution. In this paper, we present an analysis in quantum gravity that shows how boundary conditions in the future prevent a loss of quantum mechanical information from the spacetime. In classical physics, the future boundary of the spacetime in the black hole interior is a singularity. Realistic gravitational collapse results in a BKL type of approach to the singularity. But, solving the Wheeler-DeWitt equation reveals that the singularity does not form and can be replaced by specifying a final state density matrix. Such a condition is natural within the context of consistent histories version of quantum mechanics. We provide a self-contained treatment of these issues. How information escapes from the black hole will be treated elsewhere.
Quantum metaphysical indeterminacy and worldly incompleteness
| 上午4:44 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |
Torza, Alessandro (2017) Quantum metaphysical indeterminacy and worldly incompleteness. Synthese, 197. pp. 4251-4264. ISSN 1573-0964
| 上午4:44 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |
Torza, Alessandro (2021) Quantum metametaphysics. Synthese. ISSN 1573-0964
Relativistic limits on quantum operations
| 2021年8月12日 星期四 下午3:12 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |
van der Lugt, Tein (2021) Relativistic limits on quantum operations. [Preprint]
When statistical evidence is not specific enough
| 2021年8月12日 星期四 上午8:00 | | | Latest Results for Synthese |
Abstract
Many philosophers have pointed out that statistical evidence, or at least some forms of it, lack desirable epistemic or non-epistemic properties, and that this should make us wary of litigations in which the case against the defendant rests in whole or in part on statistical evidence. Others have responded that such broad reservations about statistical evidence are overly restrictive since appellate courts have expressed nuanced views about statistical evidence. In an effort to clarify and reconcile, I put forward an interpretive analysis of why statistical evidence should raise concerns in some cases but not others. I argue that when there is a mismatch between the specificity of the evidence and the expected specificity of the accusation, statistical evidence—as any other kind of evidence—should be considered insufficient to sustain a conviction. I rely on different stylized court cases to illustrate the explanatory power of this analysis.
Converting Contextuality into Nonlocality
| 2021年8月11日 星期三 下午6:00 | | | Adán Cabello | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |
Author(s): Adán Cabello
We introduce a general method which converts, in a unified way, any form of quantum contextuality, including any form of state-dependent contextuality, into a quantum violation of a bipartite Bell inequality. As an example, we apply the method to a quantum violation of the Klyachko-Can-Binicioğlu-Sh…
[Phys. Rev. Lett. 127, 070401] Published Wed Aug 11, 2021
Super-Humeanism and mental causation
| 2021年8月10日 星期二 下午12:34 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |
Esfeld, Michael (2021) Super-Humeanism and mental causation. [Preprint]
Situated Observation in Bohmian Mechanics
| 2021年8月10日 星期二 下午12:32 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |
Barrett, Jeffrey A. (2021) Situated Observation in Bohmian Mechanics. [Preprint]
| 2021年8月9日 星期一 上午8:00 | | | David Abergel | | | Nature Physics – Issue – nature.com science feeds |
Nature Physics, Published online: 09 August 2021; doi:10.1038/s41567-021-01330-z
Topological breakdown
Hans Reichenbach, radio philosopher: a preliminary report
| 2021年8月9日 星期一 上午8:00 | | | Latest Results for Synthese |
Abstract
This essay looks at some of the key aspects of Hans Reichenbach’s career as a radio engineer, broadcaster, and producer. It argues that some of the themes of Reichenbach’s logical empiricism can be illuminated by looking at them in relation to his work as a radio engineer during and after World War One. It also argues that attention to the educational activities he undertook in the new broadcast radio medium can help us understand that affinities he saw between logical empiricism and other modernizing projects of Weimar Germany.
Asymmetry cannot solve the circularity/regress problem of property structuralism
| 2021年8月9日 星期一 上午8:00 | | | Latest Results for Synthese |
Abstract
Strong dispositional monism (SDM), the position that all fundamental physical properties consist in dispositional relations to other properties, is naturally construed as property structuralism. J. Lowe’s circularity/regress objection (CRO) constitutes a serious challenge to SDM that questions the possibility of a purely relational determination of all property essences. The supervenience thesis of A. Bird’s graph-theoretic asymmetry reply to CRO can be rigorously proved. Yet the reply fails metaphysically, because it reveals neither a metaphysical determination of identities on a purely relational basis nor a determination specifically of identities in the sense of essences. Asymmetry is thus not by itself sufficient for a solution to CRO. But it cannot even help to answer CRO when a model for the determination of essences is taken as a basis. Nor is asymmetry necessary for a reply, as property structures may well be symmetric. A metaphysics of dispositional properties as grounded in a purely relational structure faces serious obstacles, and the properties would not be fundamental. Since essence and grounding are notions of metaphysical priority, there can be no essentially dispositional metaphysically fundamental properties, and the prospects of a “coherentist” metaphysics of basic properties are dim. A modal retreat that refrains from a post-modal conception of essence and simply claims that fundamental properties play dispositional roles by metaphysical necessity is unsatisfactory.
Everettian Mechanics with Hyperfinitely Many Worlds
| 2021年8月8日 星期日 上午11:53 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |
Barrett, Jeffrey A. and Goldbring, Isaac (2021) Everettian Mechanics with Hyperfinitely Many Worlds. [Preprint]
Putting probabilities first. How Hilbert space generates and constrains them
| 2021年8月8日 星期日 上午11:52 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |
Janas, Michael and Cuffaro, Michael E. and Janssen, Michel (2019) Putting probabilities first. How Hilbert space generates and constrains them. [Preprint]
