Basically little more than having a bathtub and claiming you've built a computer that does 600e23 node fluid dynamic calculations. But a lot more expensive.
Ugh, the point is a fine one but it appears it has to be made:
Validation of experimental theory through the characterization and control of an entire system is not the same as building the same system and simply seeing the final state is what you expect. The latter is much easier and says very little about your understanding.
Here's an analogy: Two people can get drunk, shack up for the night, and 9 months later have created one of the most powerful known computers: A brain. Oops. On the flip, it's unlikely we'll have a full characterization and understanding of the human brain in our lifetimes – but if we ever do, the things we'll be able to do with that understanding will very likely be profound.
My reply was glib but I think in principle correct. The idea of a strictly controlled system in the NISQ domain to validate quantum supremacy in theory is an interesting approach, but it feel deceptive to me because this 127-qubit computer cannot in fact factor 127-bit numbers with Shor's algorithm or anything like that.
The accomplishment is more akin to creating a bathtub with 127 atoms and doing fluid dynamic simulations on that, which is a much harder problem in many ways than doing the 6e25 version of the experiment. But it is very questionable to me whether any claims of quantum supremacy retain validity when leaving the NISQ domain and trying to do useful computations.
Gil Kalai's work in the area [1] continues to be very influential to me, especially what I consider the most interesting observations, namely that classical computers only barely work -- we rely on the use of long settlement times to avoid Buridan's Principle [2], and without that even conventional computers are too noisy to do actual computation.
I mean, maybe in the theoretical sense, but do conventional computers barely work in practice? Seems a bit of a pedantic argument.
Gil Kalai and others with similar arguments play an important role in the QC community. They keep the rest of us honest and help point out the gaps. But I do think the ground they have to stand on is shrinking, and fast. Ultimately, they might still be right – that much is certain – but it seems to me that the strides being made in error correction, qubit design, qubit control, hardware architecture, and software are now pushing the field into an exponential scaling regime.
To me, the big question is much less whether we'll get there, and much more "what will they be good for?"
