My background is in Physics, and in the world of science a "quantum leap" or "quantum jump" has a very specific meaning, in which an atom transitions from one energy state to another. The higher states take less energy to achieve, so in science a quantum leap is one that becomes less and less significant. I've always been amused (and bothered, I'll admit) that the metaphorical phrase has come to mean a very large advance, no matter what.
So I just checked the online Oxford English Dictionary, and found their earliest citation for the metaphorical meaning:
1956 H. L. Roberts Russia & Amer. i. 10 The enormous multiplication of power, the ‘quantum leap’ to a new order of magnitude of destruction, is something very real and comprehensible.
It may have been used before, but as far as the OED is concerned, the guilty party is one H.R. Roberts, who wrote a book called "Russia and America" that was published in 1956. However, a quick Google search turns up nothing significant about Mr. or Ms. Roberts.
Anyone know where I can find more?
(By the way, for those interested, the OED's official definition of "quantum leap" in its metaphorical meaning is "A sudden, significant, or very evident (usually large) increase or advance.")