Non-squared Kraus operators

[fnando...@gmail.com]

Hi there!

I'm using qutip since recently, and I'm enjoying it a lot... However, I'm having problems in defining CP maps with non-squared Kraus' operators (the input dimension is different from the output).

For example, if I set a Kraus operator as
K1 = Qobj([[1,0,0,0],[0,1/np.sqrt(3),1/np.sqrt(3),1/np.sqrt(3)]])
and try to define a channel as
S= sprepost(K1, K1)
I get something which is not of type super, but type=other. As such I cannot apply it on states...

Any thoughts on that?

Cheers,
Fernando.