History states of systems and operators

  title={History states of systems and operators},
  author={A. Boette and Ra{\'u}l Rossignoli},
  journal={Physical Review A},
We discuss some fundamental properties of discrete system-time history states. Such states arise for a quantum reference clock of finite dimension and lead to a unitary evolution of system states when satisfying a static discrete Wheeler-DeWitt-type equation. We consider the general case where system-clock pairs can interact, analyzing first their different representations and showing there is always a special clock basis for which the evolution for a given initial state can be described by a… 

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