I think he's referring to the general idea that transistor fabrication size shrinking cannot last forever. Since atoms have a fixed physical size, if the shrink

I think he's referring to the general idea that transistor fabrication size shrinking cannot last forever. Since atoms have a fixed physical size, if the shrinking continues indefinitely, at some point the "wires" in the transistors will become zero-atoms thick (actually a few atoms thick). See this for explanations better than I could https://en.wikipedia.org/wiki/5_nanometer https://en.wikipedia.org/wiki/5_nanometer Note the "quantum" here is not a good thing (like the theoretical "quantum speedup" possible for certain computations on quantum computers), but a bad thing: imagine you want to send current down this wire, but the current is jumpy and often leaks out of the wire to a neighbouring wire thus causing errors in computations.