Classical-quantum channels with causal and non-causal channel state information at the sender

We study an analog of the well-known Gel'fand Pinsker Channel which uses quantum states for transmission of data. We consider the case where both the sender's inputs to the channel and the channel states are elements of a finite set (cq-channel with state information at the sender). While the receiver has no information about the channel states, we distinguish between two cases at the sender: he either gets causal or non-causal channel state information. We give a single-letter description of the capacity in the first case and present two different regularized expressions of the capacity for the second. It turns out that the change from causal to non-causal channel state information at the encoder causes the complexity of numerical computation of the capacity formula to change from simple to seemingly difficult. Still, even in the difficult non-causal case we draw nontrivial conclusions, for example regarding continuity of the capacity with respect to changes in the system parameters.