[PhilPhys] Foundations of physics/Paris events

[GRINBAUM Alexei]

 <http://www-drecam.cea.fr/spec/Phocea/Vie_des_labos/Ast/ast_visu.php?id_ast=761> Forthcoming foundations of physics events in Paris
 
12 October 2007, 1-day conference " <http://www-drecam.cea.fr/spec/Phocea/Vie_des_labos/Ast/ast_visu.php?id_ast=872> Operational Approaches to Quantum Theory" (click for more information)
 
15 October 2007, Séminaire LARSIM (Amphi Bloch, Bâtiment 774, CEA-Orme des Merisiers)

à 14h15, café

à 14h30, Rob Spekkens (University of Cambridge)
"Quantum coherence: fact or fiction?"
A controversy that has arisen many times over in disparate contexts is whether quantum coherences between eigenstates of additively conserved quantities are fact or fiction. I present a pedagogical introduction to the debate in the form of a hypothetical dialogue between proponents from each of the two camps: a factist and a fictionist. It is argued that a resolution of the debate can be achieved by recognizing that quantum states do not only contain information about the intrinsic properties of a system but about its extrinsic properties as well, that is, about its relation to other systems external to it. Specifically, the coherent quantum state of the factist is the appropriate description of the relation of the system to one reference frame, while the incoherent quantum state of the fictionist is the appropriate description of the relation of the system to another, uncorrelated, reference frame. The two views are alternative but equally valid paradigms of description. This conclusion has implications for a variety of conceptual puzzles including whether it is possible to effectively "lift" superselection rules (it is, and we propose an experiment to demonstrate this for atom number). Time permitting, the connection to relationalism in quantum theory will also be discussed.

à 15h30, Alex Wilce (Susquehanna University) and Howard Barnum (Los Alamos National Laboratory)
"Tensor products and teleportation protocols in operational theories"
Working in a broad "operational" framework in which arbitrary ordered vector spaces represent the state spaces of hypothetical physical systems, we discuss state spaces of composite systems, subject to a no-signaling condition. Many familiar quantum phenomena associated with entangled states (including no-cloning and no-broadcasting theorems) already appear at this level of generality. However, the existence of teleportation protocols is a strong constraint, moving us closer to quantum theory. In this talk, we'll outline what we currently understand about teleportation in this setting; time allowing, we'll also discuss remote steering and bit commitment. Much of this represents ongoing joint work with Jon Barrett and Matt Leifer.
 
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