  Uncertainty principle plays a vital role in quantum physics. The
Wigner-Yanase skew information characterizes the uncertainty of an observable
with respect to the measured state. We generalize the uncertainty relations for
two quantum channels to arbitrary N quantum channels based on Wigner-Yanase
skew information. We illustrate that these uncertainty inequalities are tighter
than the existing ones by detailed examples. Especially, we also discuss the
uncertainty relations for N unitary channels, which could be regarded as
variance-based sum uncertainty relations with respect to any pure state.
