Understanding decoherence as an irreversible process

SEBASTIAN FORTIN; OLIMPIA LOMBARDI

INTERNATIONAL JOURNAL OF QUANTUM FOUNDATIONS

RESEARCH CENTER FOR PHILOSOPHY OF SCIENCE AND TECHNOLOGY, SHANXI UNIVERSITY

Lugar: Shanxi ; Año: 2018 vol. 4 p. 247 - 267

2375-4729

If decoherence is an irreversible process, its physical meaning might be clarified by comparing quantum and classical irreversibility. In this work we carry out this comparison, from which a unified view of the emergence of irreversibility arises, applicable both to the classical and to the quantum case. According to this unified view, in the two cases the irreversible macro-level arises from the reversible micro-level as a coarse description that can be understood in terms of the concept of projection. This position supplies an understanding of the phenomenon of decoherence different from that implicit in most presentations: the reduced state is not the quantum state of the open system, but a coarse state of the closed composite system; as a consequence, decoherence should be understood not as a phenomenon resulting from the interaction between an open system and its environment, but rather as a coarse evolution that emerges from disregarding certain degrees of freedom of the whole closed system.