Vanishing quantum discord is not necessary for completely positive maps
The description of the dynamics of a system that may be correlated with its environment is only meaningful within the context of a specific framework. Different frameworks rely upon different assumptions about the initial system-environment state. We reexamine the connections between complete positivity and quantum discord within two different sets of assumptions about the relevant family of initial states. We present an example of a system-environment state with nonvanishing quantum discord that leads to a completely positive map. This invalidates an earlier claim about the necessity of vanishing quantum discord for completely positive maps. In our final remarks, we discuss the physical validity of each approach.
has been published in Physical Review A! This paper challenges some of the main claims of one of the most cited papers in the quantum discord community. We hope this will lead to fruitful discussion on the subject.