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Luiz Carlos Ryff

Publications and source records attributed to Luiz Carlos Ryff.

17 recordsLinked to original sources
arXiv2026

How Events Separated by a Timelike Interval Can Help Us Understand Quantum Nonlocality

Quantum entanglement plays a fundamental role in quantum cryptography and computation. An important example of quantum entanglement can be found in the correlations of Einstein, Podolsky, and Rosen (EPR). However, despite the plethora of articles related to the topic, different interpretations of the EPR correlations coexist, and a consensus has not yet been reached. In this article, we seek to demonstrate, through the simple and direct application of quantum formalism, how events separated by timelike intervals can, strangely enough, help us better understand some aspects of the so-called "quantum nonlocality" associated with EPR correlations.

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arXiv2024

Reasons, Persons, and Physics

Starting from general considerations, some ideas of the philosopher Derek Parfit on consciousness, self-awareness, and reductionism are briefly reviewed and critically examined from the standpoint of physics.

physics.hist-ph↗
arXiv2024

Can Quantum Nonlocality be the Consequence of Faster-Than-Light Interactions?

It has been advocated by Bell and Bohm that the Einstein-Podolsky-Rosen (EPR) correlations are mediated through faster-than-light (FTL) interactions. In a previous paper a way to avoid causal paradoxes derived from this FTL hypothesis (via the breakdown of Lorentz symmetry) has been suggested. Lorentz transformations would remain valid, but there would be no equivalence between active and passive Lorentz transformations in the case of EPR correlations. Some counterintuitive consequences of this assumption are briefly examined here.

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arXiv2021

Comment on Wave-particle duality revisited: Neither wave nor particle

In a recent article Jan Sperling, Syamsundar De, Thomas Nitsche, Johannes Tiedau, Sonja Barkhofen, Benjamin Brecht, and Christine Silberhorn discuss the wave-particle duality using an experiment to demonstrate that "neither the wave nor the particle description is sufficient to predict the utcomes of quantum-optical experiments." I would like to draw your attention to two previous papers that discuss feasible experiments in which a photon does not seem to behave either as particle or as wave and make some brief considerations on the topic.

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arXiv2021

Comment on "Relativity of Quantum States in Entanglement Swapping: Violation of Bell's Inequality with no Entanglement"

In a recent interesting article Chris Nagele, Ebubechukwu O. IloOkeke, Peter P. Rohde, Jonathan P. Dowling, and Tim Byrnes discuss an entanglement swapping experiment using a setup where it is possible to switch the time ordering of measurements. I would like to draw your attention to the fact that the very same idea was introduced in two previous papers, and briefly address some important points related to the subject.

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arXiv2020

Einstein-Podolsky-Rosen (EPR) Correlations and Superluminal Interactions

The possible connection between EPR correlations and superluminal interactions, as suggested by Bell and Bohm, is discussed using simple and palpable arguments: (a) It is shown how an experiment based on time-like events can allow us to answer the question "Can a measurement performed on one of the photons of an entangled pair change the state of the other?" (b) The theorem on superluminal finite-speed causal influences and superluminal signaling, introduced by Scarani and Gisin, is reexamined. (c) It is shown how faster-than-light interactions and Lorentz transformations might peacefully coexist.

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arXiv2018

Quantum Nonlocality and Indistinguishability

It is shown how a "meddlesome" photon indistinguishable from another photon of an entangled pair can affect the result of an Einstein- Podolsky-Rosen (EPR) experiment. This makes it clear the importance of the notion of field over that of particle.

quant-ph↗
arXiv2016

Comment on "On Phase Selective Quantum Eraser" (arXiv:1501.00817 [quant-ph])

In a recent interesting article A. Heuer, G. Pieplow, and R. Menzel discuss a quantum-eraser experiment to investigate the complementarity of wave-like and particle-like behavior of photons. I would like to draw your attention to the fact that the very same experimental setup was suggested in a previous paper, and take advantage of this opportunity to examine some aspects of this controversial subject.

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arXiv2013

Null-Result Detection and Einstein-Podolsky-Rosen (EPR) Correlations

It follows from Bell's theorem and quantum mechanics that the detection of a particle of an entangled pair can (somehow) "force" the other distant particle of the pair into a well-defined state (which is equivalente to a reduction of the state vector): no property previously shared by the particles can explain the predicted correlations. This result has been corroborated by experiment. However, it has not been experimantally proved-and it is far from obvious-that the absence of detection, as in null-result (NR) experiments could have the very same effect. In this paper a way to try to bridge this gap is suggested. As already shown for the case of EPR correlations, if NR detections cannot induce a reduction of the state vector, then faster-than-light (FTL) communication becomes possible, at least in prínciple. But it will be demonstrated that-as entertained by Bohm-this does not necessarily lead to a causal paradox, or to the rejection of the Lorentz transformations.

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arXiv2009

Bell's Conjecture and Faster-Than-Light Communication

The Bell-wave (B-wave) supposition has been introduced in an attempt to investigate Bell's conjecture (according to which "behind the scenes something is going faster than light"). Here it is shown, for the case of two entangled photons, that if it is further assumed that the B-waves propagate with superluminal but finite velocity then it is possible, at least in principle, to have faster-than-light (FTL) communication.

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arXiv2009

Comment on "Bell inequalities and quantum mechanics" by J. H. Eberly

Errors in Eberly's derivation of several Bell inequalities are pointed out: (1) it is based on an equation that is incorrect; (2) it uses neither two-particle states nor locality to derive Bell's inequalities and; (3) it does not use entanglement to obtain violations of Bell's inequalities. Even leading and outstanding physicists -- as certainly is the case of Prof. Eberly -- sometimes make elementary mistakes, and this by no means diminishes the importance of their scientific contribution. In general, this is a consequence of an excessive attachment to an idea (nowadays it has become fashionable to be against realism). This shows the importance of trying to keep an open mind.

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arXiv2008

Proposal For Testing Bell's Conjecture

A simple nonlocal mechanism for Einstein-Podolsky-Rosen (EPR) correlations inspired by Bell's conjecture (according to which "behind the scenes something is going faster than light") is suggested, and an experimental test is proposed.

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arXiv2006

Bell's Theorem Reexamined

An Einstein-Podolsky-Rosen (EPR)-like argument using events separated by a time-like interval strongly suggestes that measuring the polarization state of a photon of an entangled pair changes the polarization state of the other distant photon. Trough a very simple demonstration, the Wigner-D'Espagnat inequality is used to show that in order to prove Bell's theorem neither the assumption that there is a well-defined space of complete states $λ$ of the particle pair and well-defined probability distribution $ρ(λ)$ over this space nor the use of counterfactuals is necessary. These results reinforce the viewpoint that quantum mechanics implicitly presupposes some sort of nonlocal connection between the particles of an entangled pair. As will become evident from our discussion, relinquishing realism and/or free will cannot solve this apparent puzzle.

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arXiv2000

A Mach-Zehnder Interferometer for a Two-Photon Wave Packet

We propose an experiment that permits observation of the de Broglie two-photon wave packet behavior for a pair of photons, using a Mach-Zehnder interferometer. It is based on the use of pulsed lasers to generate pairs of photons via spontaneous parametric down-conversion and the post-selection of events. It differs from previous realizations by the use of a third time-correlated photon to engineer the state of the photons. The same technique can give us which-path information via an ``interaction-free'' experiment and can be used in other experiments on the foundations of quantum mechanics related to wave-particle duality and to nonlocality.

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