We consider the space B logα , of analytic functions on the unit disk D, defined by the requirement ∫ D |f (z)|φ(|z|) dA(z) < ∞, where φ(r) = log(1/(1 − r)) and show that it is a predual of the “log-Bloch” space and the dual of the corresponding little Bloch space. We prove that a function f(z) = ∑ ∞ n=0 anz with an ↓ 0 is in B1logα iff ∑ ∞ n=0 log(n+2)/(n+1) < ∞ and apply this to obtain a crit...

We use polarization operators known from quantum theory of angular momentum to expand the N ×N dimensional density operators. Thereby, we construct generalized Bloch vectors representing density matrices. We study their properties and derive positivity conditions for any N. We also apply the procedure to study Bloch vector space for a qubit and a qutrit.

We give a characterization of lacunary series in the Bloch space of the unit ball in C in terms of Taylor coefficients. We also characterize Bloch functions whose Taylor coefficients are nonnegative. The corresponding problems for BMOA are discussed as well.