Quantum Klein Space and Superspace
  We give an algebraic quantization, in the sense of quantum groups, of the
complex Minkowski space, and we examine the real forms corresponding to the
signatures $(3,1)$, $(2,2)$, $(4,0)$, constructing the corresponding quantum
metrics and providing an explicit presentation of the quantized coordinate
algebras. In particular, we focus on the Kleinian signature $(2,2)$. The
quantizations of the complex and real spaces come together with a coaction of
the quantizations of the respective symmetry groups. We also extend such
quantizations to the $\mathcal{N}=1$ supersetting.
