Weekly Papers on Quantum Foundations (12)

On Two Recent Approaches to the Born Rule. (arXiv:2103.09910v1 [quant-ph])

上午9:59|Blake C. Stacey|quant-ph updates on arXiv.org

I comment briefly on derivations of the Born rule presented by Masanes et al. and by Hossenfelder.

Experimental SWAP test of infinite dimensional quantum states. (arXiv:2103.10219v1 [quant-ph])

上午9:59|Chi-Huan Nguyen, Ko-Wei Tseng, Gleb Maslennikov, H. C. J. Gan, Dzmitry Matsukevich|quant-ph updates on arXiv.org

Efficient overlap estimation of high-dimensional quantum states is an important task in quantum information and a core element in computational speedups of quantum machine learning. Here we experimentally demonstrate the SWAP test that measures the overlap of two motional states in a system of trapped $^{171}\mathrm{Yb}^+$ ions. To illustrate the versatility of our implementation, we report the overlap measurement of a variety of quantum states: Fock states, coherent states, squeezed vacuum states, and cat states. We highlight applications of the SWAP test by measuring the purity of mixed states. Our results enable quantum information processing with high dimensional quantum states.

Classical causal models cannot faithfully explain Bell nonlocality or Kochen-Specker contextuality in arbitrary scenarios. (arXiv:1909.05434v3 [quant-ph] UPDATED)

上午9:59|J. C. Pearl, E. G. Cavalcanti|quant-ph updates on arXiv.org

In a recent work, it was shown by one of us (EGC) that Bell-Kochen-Specker inequality violations in phenomena satisfying the no-disturbance condition (a generalisation of the no-signalling condition) cannot in general be explained with a faithful classical causal model — that is, a classical causal model that satisfies the assumption of no fine-tuning. The proof of that claim however was restricted to Bell scenarios involving 2 parties or Kochen-Specker-contextuality scenarios involving 2 measurements per context. Here we show that the result holds in the general case of arbitrary numbers of parties or measurements per context; it is not an artefact of the simplest scenarios. This result unifies, in full generality, Bell nonlocality and Kochen-Specker contextuality as violations of a fundamental principle of classical causality. We identify, however, an implicit assumption in the former proof, making it explicit here: that certain operational symmetries of the phenomenon are reflected in the model, rather than requiring fine-tuned choices of model parameters. This clarifies a subtle but important distinction between Bell nonlocality and Kochen-Specker contextuality.

3D-Space and the preferred basis cannot uniquely emerge from the quantum structure. (arXiv:2102.08620v3 [quant-ph] UPDATED)

上午9:58|physics.hist-ph updates on arXiv.org

Authors: Ovidiu Cristinel Stoica

Is it possible that only the state vector exists, and the 3D-space, a preferred basis, a preferred factorization of the Hilbert space, and everything else, emerge uniquely from the Hamiltonian and the state vector?

In this article no-go theorems are given, showing that whenever such a candidate preferred structure exists and can distinguish among physically distinct states, infinitely many physically distinct structures of the same kind exist. The idea of the proof is very simple: it is always possible to make a unitary transformation of the candidate structure into another one of the same kind, but with respect to which the state of the system at a given time appears identical to its (physically distinct) state at any other time, or even to states from “alternative realities”.

Therefore, such minimalist approaches lead to strange consequences like “passive” travel in time and in alternative realities, realized simply by passive transformations of the Hilbert space.

These theorems affect all minimalist theories in which the only fundamental structures are the state vector and the Hamiltonian, whether they assume branching or state vector reduction, in particular, the version of Everett’s Interpretation coined by Carroll and Singh “Mad-dog Everettianism”, various proposals based on decoherence, proposals that aim to describe everything by the quantum structure, and proposals that spacetime emerges from a purely quantum theory of gravity.

The Stable Marriage Problem: An interdisciplinary review from the physicist’s perspective

上午9:58|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 16 March 2021

Source: Physics Reports

Author(s): Enrico Maria Fenoaltea, Izat B. Baybusinov, Jianyang Zhao, Lei Zhou, Yi-Cheng Zhang

Schr\”odinger’s cat for de Sitter spacetime. (arXiv:2012.10025v2 [gr-qc] UPDATED)

上午9:58|gr-qc updates on arXiv.org

Authors: Joshua FooRobert B. MannMagdalena Zych

Quantum gravity is expected to contain descriptions of semiclassical spacetime geometries in quantum superpositions. To date, no framework for modelling such superpositions has been devised. Here, we provide a new phenomenological description for the response of quantum probes (i.e. Unruh-deWitt detectors) on a spacetime manifold in quantum superposition. By introducing an additional control degree of freedom, one can assign a Hilbert space to the spacetime, allowing it to exist in a superposition of spatial or curvature states. Applying this approach to static de Sitter space, we discover scenarios in which the effects produced by the quantum spacetime are operationally indistinguishable from those induced by superpositions of Rindler trajectories in Minkowski spacetime. The distinguishability of such quantum spacetimes from superpositions of trajectories in flat space reduces to the equivalence or non-equivalence of the field correlations between the superposed amplitudes.

Typicality of Dynamics and Laws of Nature

上午3:45|Philsci-Archive: No conditions. Results ordered -Date Deposited.

Filomeno, Aldo (2021) Typicality of Dynamics and Laws of Nature. [Preprint]

The Philosophy of Quantum Computing

2021年3月17日 星期三 上午10:56|Philsci-Archive: No conditions. Results ordered -Date Deposited.

Cuffaro, Michael E. (2021) The Philosophy of Quantum Computing. [Preprint]

Does the No Alternatives Argument need Gerrymandering to Be Significant?

2021年3月17日 星期三 上午10:51|Philsci-Archive: No conditions. Results ordered -Date Deposited.

Dawid, Richard (2021) Does the No Alternatives Argument need Gerrymandering to Be Significant? [Preprint]

Four Postulates of Quantum Mechanics Are Three

2021年3月16日 星期二 下午6:00|Gabriele Carcassi, Lorenzo Maccone, and Christine A. Aidala|PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Author(s): Gabriele Carcassi, Lorenzo Maccone, and Christine A. Aidala

The tensor product postulate of quantum mechanics states that the Hilbert space of a composite system is the tensor product of the components’ Hilbert spaces. All current formalizations of quantum mechanics that do not contain this postulate contain some equivalent postulate or assumption (sometimes…

[Phys. Rev. Lett. 126, 110402] Published Tue Mar 16, 2021

Gauge-underdetermination and shades of locality in the Aharonov-Bohm effect

2021年3月15日 星期一 下午4:20|Philsci-Archive: No conditions. Results ordered -Date Deposited.

Mulder, Ruward A. (2021) Gauge-underdetermination and shades of locality in the Aharonov-Bohm effect. [Preprint]

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