arXiv:1502.07086v1 [quant-ph] 25 Feb 2015 Quantum entropy of systems coupled to sinks or sources Alessandro Sergi 1,2, * and Konstantin G. Zloshchastiev 1, † 1 School of Chemistry and Physics, University of KwaZulu-Natal in Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa 2 KwaZulu-Natal Node, National Institute for Theoretical Physics (NITheP), South Africa (Dated: February 26, 2015) Abstract We have studied the quantum entropy for systems which are coupled to sinks or sources. We generalize the von Neumann entropy to this case and prove that its production is in general different from zero. Such a generalization captures the expected behavior of the entropy as a measure of disorder in quantum dissipative systems. We illustrate the theory by explicitly studying a tunneling model with two energy levels and detuning. PACS numbers: 03.65.-w, 05.30.-d, 03.65.Yz, 03.65.Aa * Electronic address: sergi@ukzn.ac.za † Electronic address: k.g.zloschastiev@gmail.com 1