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Sep14-07, 01:41 PM
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Quote Quote by reilly View Post

This abstract approach tells us that classical and quantum probabilities are generically the same -- they both can be described by dynamical equations for the probablity distribution-- the differences between the details, like interference phenomena, are due to the different dynamics, and to generally different initial conditions.

But there are some major differences. First of all the "probabilistic" nature of quantum mechanics only comes into play when we want to MEASURE something (neglecting the effect of dissipation for the moment), as long as a system is left to evolve on its own it is complettely deterministic; this is why we can use superposition to build quantum computers and in other QIP applications.
Real systems are of course always open meaning we still usually need to use statistical quantum mechanics to predict the outcome of experiments, but that is a "technical" detail which rarely changes any qualitative properties of a system; the only difference between Rabi oscillations in a closed and an open system is that they are attenuated in the latter, but there are still oscillations and the basic physics is the same.