I'm guessing a report stuck the word quantum in there, just because it seemed like a nice modifier. The CalTech video referenced indeed describes just classic

I'm guessing a report stuck the word quantum in there, just because it seemed like a nice modifier. The CalTech video referenced indeed describes just classical wave interference controlled by a phased array transmitter, as you suggest. As for how much power - the team only claims to have "detected" the beam, not to have captured and utilized it, when transmitting from orbit to earth. Given that even with less than a meter between the transmitter and receiver, they only lit up a couple of LEDs, I think discussions of power are a bit premature.