So I am minimising over the difference in probality of making a certain measurement (in the learnt and optimal case). This probability is determined by both the imaginary and real part of the amplitude. And the values that I am optimising over influence the final state of the system in a way determined by complex functions. So there is no way (to my knowledge) to rewrite the system in such a way that I can get rid of these complex values here without loosing a lot of information.
I will have a look at the preview nightly and perhaps define my own linear.
Thanks for your help,
Merel