That's an interesting question. Supercavitating torpedoes take advantage of two effects (a) gas typically is much less viscous than liquid, which reduces drag a

That's an interesting question. Supercavitating torpedoes take advantage of two effects (a) gas typically is much less viscous than liquid, which reduces drag and (b) if you reduce the pressure enough, liquid turns into gas. In the atmosphere, you're already in a gas, so there's not an obvious other state of matter that would be advantageous. Furthermore, reducing pressue would certainly reduce drag, but not by orders of magnitude like a phase transition. But in the spirit of 'yes, and': if you reduced pressure near the skin by A LOT (near vacuum) you might see a dramatically lower drag. Maybe that could be accomplished by ionising the incoming air and then electrostatically repelling it? Who knows. It's fun to speculate though.