Iodine in water ionized on the picosecond scale, by laser pulse.

Would be mildly surprised if that didn't happen that fast. I guess the interesting twist is that the medium is flowing liquid.

How long does this state last? If one were to, say, write a series of bits into the upstream side of the flow, how many such bits could you recover downstream? The potential I see here is possibly a delay line for THz band signals, not so much the basis for logic for a 1000GHz CPU. But delay lines are darned useful things.