The comment above yours said "and then ... detect the difference", implying sequential action and a real change of state - not simultaneous action+measure. """

The comment above yours said "and then ... detect the difference", implying sequential action and a real change of state - not simultaneous action+measure. """Because the laser pulse is so fast, the water can switch states in a matter of picoseconds, which are trillionths of a second.""" Although after reading, I must agree that the time-scale feels quite ridiculous!! (EDIT: RE: "Capacitors can't be logic gates" below - Maybe. But if 1+0=1, and 1+1=2, then surely differentiating 0/1 vs 2 on the output creates an AND gate?) (I am "posting too fast" with 3 posts in the last hour. Sorry :)