Hi, im a bit confused about unitary time evolution, I understand that a closed quantum system can be explained by unitary time evolution which ensures that the probability of all possible outcomes is always 1. But for an open quantum system we can't in general explain it with a unitary time evolution. This is where I get confused, we explain the evolution of an open quantum systems with the density matrix ##\rho(t)##, which must always satisfy ##Tr[\rho(t)]=1##, so my question is, how is this not unitary time evolution? Thanks.(adsbygoogle = window.adsbygoogle || []).push({});

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# I Unitary time evolution

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