Cristian Lopez

Measurement, Interpretation and Information

During many years since the birth of quantum mechanics, instrumentalist interpretations prevailed: the meaning of the theory was expressed in terms of measurements results. However, in the last decades, several attempts to interpret it from a realist viewpoint have been proposed. Among them, modal interpretations supply a realist non-collapse account, according to which the system always has definite properties and the quantum state represents possibilities, not actualities. But the traditional modal interpretations faced some conceptual problems when addressing imperfect measurements. The modal-Hamiltonian interpretation, on the contrary, proved to be able to supply an adequate account of the measurement problem, both in its ideal and its non-ideal versions. Moreover, in the non-ideal case, it gives a precise criterion to distinguish between reliable and non-reliable measurements. Nevertheless, that criterion depends on the particular state of the measured system, and this might be considered as a shortcoming of the proposal. In fact, one could ask for a criterion of reliability that does not depend on the features of what is measured but only on the properties of the measurement device. The aim of this article is precisely to supply such a criterion: we will adopt an informational perspective for this purpose.During many years since the birth of quantum mechanics, instrumentalistinterpretations prevailed: the meaning of the theory was expressed in terms of measurementsresults. However, in the last decades, several attempts to interpret it from a realist viewpointhave been proposed. Among them, modal interpretations supply a realist non-collapseaccount, according to which the system always has definite properties and the quantum staterepresents possibilities, not actualities. But the traditional modal interpretations faced someconceptual problems when addressing imperfect measurements. The modal-Hamiltonianinterpretation, on the contrary, proved to be able to supply an adequate account of themeasurement problem, both in its ideal and its non-ideal versions. Moreover, in the non-idealcase, it gives a precise criterion to distinguish between reliable and non-reliable measurements.Nevertheless, that criterion depends on the particular state of the measured system, and thismight be considered as a shortcoming of the proposal. In fact, one could ask for a criterionof reliability that does not depend on the features of what is measured but only on theproperties of the measurement device. The aim of this article is precisely to supply such acriterion: we will adopt an informational perspective for this purpose.

No communication without manipulation: A causal-deflationary view of information

In this paper, we shall describe a new account of information in communicational contexts, namely, a causal-deflationary one. Our approach draws from Timpsons deflationary view and supplies the field of philosophy of information with new tools that will help to clarify the underlying structure of communication: information is an abstract entity that must be involved in a causal link in order to achieve communication. In light of our account, communication is not merely the existence of statistical correlations between source and receiver, as usually understood from a purely formal view. Instead, communication is an asymmetric phenomenon involving causal notions: the destination system must be able to be causally manipulated by intervening on the source for successful communication. In a nutshell, we shall support the following lemma: no communication without manipulation.

On the Tension between Ontology and Epistemology in Quantum Probabilities

I propose a physical underpinning of the uncertainty relations (and with them, of quantum probabilities) which is dynamical, finitist, operational and objective. Under this view which dispels of the metaphysics that surrounds the quantum state or the ”wave particle duality”, quantum probabilities are objective dynamical transition probabilities between finite resolution measurement results. As such they can qualify as an objective alternative to the subjective view that the quantum information theoretic approach adheres to. 1 Chance and Subjectivity Despite the so called ”quantum revolution”, determinism is still the working hypothesis of modern physics. When it comes to our physical theories, the mathematical requirement for existence and uniqueness of solutions to the initial conditions, irrespective of the the dynamical model that is used to describe the phenomena, is, and has been since the inception of mathematical physics, the first consistency test that such a model must ∗HPSC Department, Indiana University, Bloomington, hagara@indiana.edu. I am grateful to Olival Freire Jr. from the Program of History of Physics at the Institute of Physics, UFBA, where this project was conceived, under the generous support of the Fulbright Mobility Award to Brazil. Thanks also to G. Ortiz (IU Physics) for discussion, and for O. Lombardi for tolerating my heretic views.

Los Múltiples Rostros de la Filosofía de la Información

La filosofia de la informacion ha experimentado un enorme auge en los ultimos anos, consolidandose como un ambito de indagacion filosofica autonomo. Su tema de estudio, el concepto de informacion, es uno de los terminos mas comunes y extendidos en nuestros dias, abarcando ambitos tan disimiles como el lenguaje cotidiano y la mecanica cuantica. Esta presencia ubicua y universal del termino es lo que conduce a que su analisis y abordaje filosofico sea una empresa sumamente compleja y desafiante. El presente articulo pretende ofrecer algunas lineas generales que permitan distinguir diferentes tipos de informacion, diferentes enfoques, diferentes contextos donde el concepto es utilizado y diferentes interpretaciones. De esta manera, se muestra que la filosofia de la informacion es un ambito sumamente diverso y plural, donde el concepto de informacion tiene tantos significados, como usos y contextos.

Classical and quantum information: two kinds of information?

El presente articulo busca ofrecer un analisis conceptual de la nocion de informacion, a partir del modo en que es definida por las teorias formales de Claude Shannon y de Benjamin Schumacher. Contra la postura segun la cual existen dos tipos de informacion de naturalezas diferentes, una informacion clasica y una informacion cuantica (definidas por las teorias de Shannon y de Schumacher respectivamente), aqui argumentamos que no hay razones suficientes para sostener la existencia de la informacion cuantica como un nuevo tipo sustancialmente distinto de informacion. Afirmamos asi que existe un unico tipo de informacion que puede ser codificado de diversas maneras, en particular, mediante sistemas clasicos o sistemas cuanticos. Esta posicion nos conducira a concebir un concepto unificado y abstracto de informacion, en un contexto donde (1) la teoria de Shannon resulta neutral e independiente de las teorias fisicas utilizadas para describir las partes involucradas en el proceso de transmitir informacion, y (2) la teoria de Schumacher no define un nuevo tipo de entidad informacional, sino una manera alternativa de codificar la informacion mediante estados cuanticos.