Is there a metric which lets us track how far/close we are to do something useful with quantum computers?
And when we look at that metric and extrapolate its progression over the last years, when do we expect QCs to hit datacenters?
And when we look at that metric and extrapolate its progression over the last years, when do we expect QCs to hit datacenters?
It crowdsources new submissions to the chart if there are ones you see missing (just open a PR)
Citation needed
Basically we are far enough out from "useful" QC that its anyone's guess (except for the people trying to convince you to invest in their startup). That said relavent metrics include number of qubits and their error rate (once you get past a certain number with a low enough error rate you can start to use error correction which is when things really start to become interesting)
It does depend a bit on what you mean by "useful" though see also https://en.wikipedia.org/wiki/Noisy_intermediate-scale_quant...
QC startups should be funded because industry is a crucial component of QC progress and large-scale QC labs (Google, IBM e.t.c) can't work on all the ideas. The ideas that come from startups do accelerate QC development.