DECOHERENCE AND RECOHERENCE IN AN ANALOG OF THE BLACK-HOLE INFORMATION PARADOX

We analyze a system consisting of an oscillator coupled to a field. Wi th the field traced out as an environment, the oscillator loses cohere nce on a very short decoherence time scale; but, on a much longer rela xation time scale, it evolves predictably into a unique, pure (ground) state. This example of recoherence has interesting implications both for the interpretation of quantum theory and for the loss of informati on during black hole evaporation - the so-called black hole informatio n paradox. We examine these implications by investigating the intermed iate and final states of the quantum field, treated as an open system coupled to an unobserved oscillator.