The conceptual meaning of reduced states: decoherence and interpretation

J. S. ARDENGHI; S. FORTIN; O. LOMBARDI

Nancy

Congreso; 14th Congress of Logic, Methodology and Philosophy of Science; 2011

International Union of History and Philosophy of Science

The interpretation of reduced states as quantum states is a common practice in physics. The aim of this paper is to reject this usual interpretation on the basis of a twofold argument. First, we will argue that the reduced state of a decohering system is a coarse-grained state, analogous to the coarse-grained descriptions of unstable classical systems. Second, in the context of no-collapse interpretations we will show that, even in the case of non-interacting subsystems, the move of conceiving their reduced states as their legitimate quantum states precludes the account of consecutive measurements.