January 22, 2007
Von Neumann's quantum measurement protocol is outlined in terms of thermodynamics. In particular, based on the separation between quantum and classical realms implied in the Copenhagen interpretation, the entanglement generated from the interaction between the system and the apparatus yields a negative conditional entropy in the quantum component. On the other hand, the Heisenberg cut implies mandatory tracing out of the system part, and the resulting apparatus corresponds to a classical system. This measurement process exhibits a conservation of energy between quantum and classical systems, analogous to the first law of thermodynamics. Moreover, an exact amount of entropy increase in apparatus may shed light on a connection between the first and second laws of thermodynamics.
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