the.com/quantum leap

means A sudden, dramatic advance or breakthrough — not a gradual step, but a decisive jump to a whole new level.

from In quantum physics, a 'quantum leap' (or quantum jump) is the abrupt transition of an electron from one discrete energy level to another, with no smaller steps in between — a tiny, instantaneous change at the atomic scale. When the phrase entered everyday English in the mid-20th century, people seized on the word 'leap' and the drama of 'quantum' as in 'quantity,' and the term flipped meaning entirely: instead of describing physics' smallest measurable jump, it came to describe the biggest conceivable one. The irony is baked in — scientists use it for the minuscule, everyone else uses it for the monumental.