But to be honest, I don't really care what's correct, I'll just keep avoiding to use that word. If people can't agree on the meaning, it's useless.
The word quantum, when used in the phrase "quantum leap," is meant to describe a
sudden, instantaneous jump from 'one level' up to the 'next level' (of whatever it is that one is measuring), as opposed to a
gradual, continuous change...
. . . so, anything that could be considered an immediate "game-changer" in its field, or that suddenly "takes things to a whole new level," could be described as representing a "quantum leap" in its field.
<gratuitous, math-free, oversimplification>
The expression comes from an analogy with the old-fashioned way of describing an atom as a nucleus with one or more electrons orbiting around it, in much the same way that the earth revolves around the sun. That's not what really happens, but it's sufficient for casual discussions like this.........
Scientists discovered that an electron could travel around the nucleus in
more than one 'orbital', depending upon how energetic it was.
They then realized that an electron could only travel around the nucleus in
certain specific, well-defined orbitals, and that it could be made to "transition" from a 'lower orbital' into a 'higher orbital', by directing energy (
e.g., pointing a laser) at it.
The "energized" electron would eventually drop back down to its 'lower orbital', releasing (say) a photon in the process to get rid of the extra energy.
Returning to the planetary analogy for a moment, it would be the equivalent of giving the Earth enough of a push to make it go around the sun
in Mars's orbit for a while, before eventually returning to its original Earth-sized orbit.
The key thing —
the quantum thing — was that electrons could not transition from one orbital to a higher or lower orbital as a
continuous process (like rolling a rock up or down a hill); they could only make
instantaneous jumps from one orbital to another, and only when they absorbed (or emitted) the precise discrete amounts (
i.e., '
quanta') of energy needed to make each particular up- or down- transition happen.
</gratuitous, math-free, oversimplification>
It's true that the quanta with which quantum physicists grapple are all extreeeeeeeeeemely tiny, but it's the "
immediate and incremental change, as opposed to gradual and continuous change" aspect of the word "quantum" that is leveraged in that expression, which describes sudden major changes, as opposed to slower, continuous, more 'evolutionary' processes.
