# Entropy change in Heisenberg picture

If we stick with Heisenberg picture where density matrix $\rho$ is constant, how do we account for entropy increase?

I've read the answer to State collapse in the Heisenberg picture but I don't see how the explanation can be used to incorporate the increase of entropy, if it is defined like $$S = \operatorname{Tr} (\rho \ln \rho).$$

Or is Shroedinger picture preferable for irreversible evolution?

1. You're missing a minus in the entropy definition - $S=-Tr(\rho\ln\rho)$