Possible erratum
The article says that the relationship between number of (binary equivalent) bits that a gate can hold and the number of separate states, between which it can distinguish is a factor of two:
binary bits | distinct states
1 | 2
2 | 4
3 | 6
4 | 8
This is surely false! the relationship between number of binary bits b that can be represented by a gate that can distinguish n states is: n=2^b or b=log(n)/log(2).
i.e.:
binary bits | distinct states
1 | 2
2 | 4
3 | 8
4 | 16