Bad Astronomy: Misconceptions and Misuses Revealed, from ...

IDIOM’S DELIGHT 35
So you might conclude that an ad bragging about a product
being a quantum leap over other products is silly, since it means
it’s ahead by only 0.00000000001 centimeters!
You might be surprised to find out that I have no problem
with this phrase. I don’t think it’s bad at all! The actual distance
jumped may be small, but only on our scale. To an electron it truly
is a quantum leap, a sudden jump from one stage to the next. The
phrase itself has nothing to do with the absolute distance the electron
moved, but everything to do with its being a major leap forward,
skipping the intervening space and landing in a new spot far
ahead of where it was.
Sometimes people say that when something is easy, it isn’t
exactly rocket science. But in this case, maybe it is!