There are many fields in which a word or phrase has crossed over from a very specific, esoteric use, into the every day world. Sometimes the way it is used by the general public bears no relation to the original intent of the word or phrase.
In layman world the term ‘quantum leap’ is used to describe a massive jump - usually related to a thought process. “I see where you’re coming from, but it’s a quantum leap to suggest that outcome!”
In physics world, that is as wrong a usage of the term as could be. A ‘quantum leap’ is in fact infinitesimally small - and quite mysterious. It describes the moment an electron jumps from one energy level to another within an atom. Strangely, the actual leap cannot be witnessed. The electron disappears from one level and reappears on another.
“You may think that sounds like nonsense, but when we look at things in the universe that are extremely small, extremely massive, or travelling extremely fast, they just don’t behave in familiar ways. In fact, many of the phenomena we encounter inside the atom have no analogs in our everyday experience.” ‘Science Matters’ by Robert M. Hazen and James Trefil.