Comment Re:Quantum fusion? (Score 3, Interesting) 19
In the case of both quantum computing and commercial fusion reactors we're making progress pretty rapidly. A major reason that fusion has been so slow compared to some predictions is that simply put, the amount of funding for it has been well below projections. See https://www.reddit.com/r/energy/comments/5budos/fusion_is_always_50_years_away_for_a_reason/?onetap_auto=true&one_tap=true#lightbox this graph. But the fusion situation is getting better, and rapidly. The triple product, a useful way of measuring how close a fusion reactor is to being self-sustaining has shown major improvement the last few years and it continues to get better https://www.fusionenergybase.com/article/measuring-progress-in-fusion-energy-the-triple-products Better computer modeling of what is happening in reactors, as well as better superconductors have helped a lot. And there's another large-scale change with fusion reactors which that we're starting to see a lot more private investment. Now, some of that is clearly due to hype, but a lot of it looks promising, and also helps show that the tech is getting to the point where it has some decent chance. If fusion fails to be commercially viable the most likely way that will happen is that by the time it would be otherwise viable, it will be competing with just really efficient solar and wind which are showing drastic improvements in cost the last few years.
For quantum computers the situation is not as good. But there's still clear improvements the last few years in at least three major respects. First, there's been major improvements on quantum error corrections. https://en.wikipedia.org/wiki/Quantum_error_correction Due to the inherent noisiness of quantum computers due to stray particles and the like, quantum error correction is really important. But the early error correction algorithms were just not that good. One of the first discovered was Shor's code which required 9 extra qubits for each logical qubit. But that was replaced with the CSS code which was much more efficient https://en.wikipedia.org/wiki/CSS_code, and subsequent codes are even more efficient or allow one to play with tradeoffs. Second, we're much better at keeping qubits entangled with many others or for long periods of time. See for example, https://www.newscientist.com/article/2382022-record-breaking-number-of-qubits-entangled-in-a-quantum-computer/ Third, and closely connected to 1 and 2, there are now real demonstrations of CSS and similar approaches on physical qubits. See e.g. discussion here https://scottaaronson.blog/?p=7651.
It does not seem like either of these techs is going to be practical for a few years yet. But there's clear progress in both and at a rapid rate.