The idea is that if it costs $r to store a base-r digit, then base 3 (or e in a continuous scale) turns out to be the most efficient. Obviously, there's no a priori reason to think that a 3-level gate is exactly 1.5x more expensive than a 2-level gate, so this is mostly of theoretical interest.
The idea is that if it costs $r to store a base-r digit, then base 3 (or e in a continuous scale) turns out to be the most efficient. Obviously, there's no a priori reason to think that a 3-level gate is exactly 1.5x more expensive than a 2-level gate, so this is mostly of theoretical interest.