  The Holevo-Schumacher-Westmoreland (HSW) classical (entanglement-unassisted)
channel capacity for a class of qudit unital channels is shown to be C =
log2(d) - Smin, where d is the dimension of the qudit, and Smin is the minimum
possible von Neumann entropy at the channel output. The HSW channel capacity
for tensor products of this class of unital qudit channels is shown to obey the
same formula.
