  The variance of quantum channels involving a mixed state gives a hybrid of
classical and quantum uncertainties. We seek certain decomposition of variance
into classical and quantum parts in terms of the Wigner-Yanase skew
information. Generalizing the uncertainty relations for quantum observables to
quantum channels, we introduce a new quantity with better quantum mechanical
nature to describe the uncertainty relations for quantum channels. We derive
several uncertainty relations for quantum channels via variances and the
Wigner-Yanase skew information.
