Quantum Darwinism: Entanglement, branches, and the emergent classicality of redundantly stored quantum information

2005/05/31 by Robin Blume-Kohout, W. H. Zurek · 1 voice
Physics and Astronomy · #quant-ph

paper · pdf · doi:10.1103/physreva.73.062310

published as Phys. Rev. A 73, 062310 (2006) · 22 pages, RevTeX4. Color figures. Revised in light of referee comments from PRA; improved presentation, no major content changes

arxiv created 2005/10/13 · arxiv updated 2009/12/01

Abstract

We lay a comprehensive foundation for the study of redundant information storage in decoherence processes. Redundancy has been proposed as a prerequisite for objectivity, the defining property of classical objects. We consider two ensembles of states for a model universe consisting of one system and many environments: the first consisting of arbitrary states, and the second consisting of ``singly-branching'' states consistent with a simple decoherence model. Typical states from the random ensemble do not store information about the system redundantly, but information stored in branching states has a redundancy proportional to the environment's size. We compute the specific redundancy for a wide range of model universes, and fit the results to a simple first-principles theory. Our results show that the presence of redundancy divides information about the system into three parts: classical (redundant); purely quantum; and the borderline, undifferentiated or ``nonredundant,'' information.

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Discussions

• In classical physics the equations of motion for the $x$ position of a particle are written in terms of a function $x(t)$ such that if you measure $x$ at time $t$ , you get the answer $x(t)$ . In quan [stackexchange, 1 points]