I myself am getting at PhD in quantum information. I completely agree that the timeline for quantum computing was extremely optimistic 20 years ago. However, I think current estimates are much closer to the truth. We now have a much better understanding of the systems on which we are building QCs. Estimates of fault-tolerance thresholds have become much better. We have 20 years of experimental progress to extrapolate when we expect to hit these thresholds.
I agree that progress in the 20s and 70s was much faster. But they were grabbing onto low-hanging fruit. Building even a 'bad' quantum computer is several orders of magnitude more difficult task than building, say, a 486 processor. The degree of experimental control required is much much more. What I see looking back is steady progress towards greater experimental control in multiple systems and very frequent and steady achievements of milestones.
What you forget when you compare quantum computing with DNA sequencing or image recognitions is that quantum computing is at the bottom of current theoretical paradigm. When you do DNA sequencing the science of your instruments (eg. centrifuges) is not suspect. In QC everything is suspect; your system, your detection mechanisms, your control systems. If you normalize every field by its fundamental difficulty you will find that quantum information is keeping up with other fields.
I would argue that this difficulty is not more fundamental than difficulty of producing light bulbs by Edison.
The thing I do not want to normalize w field by its difficulty - then progress would be just related to the effective number of smart people working on it.
I was raised in a scientific culture (Central/Eastern Europe), where difficulty was a virtue, not - impact. But that way produces a --lot-- small number (because they are difficult!) of difficult results, with little impact.
Likewise, the most progress happens where there are low-hanging fruits.
I agree that progress in the 20s and 70s was much faster. But they were grabbing onto low-hanging fruit. Building even a 'bad' quantum computer is several orders of magnitude more difficult task than building, say, a 486 processor. The degree of experimental control required is much much more. What I see looking back is steady progress towards greater experimental control in multiple systems and very frequent and steady achievements of milestones.
What you forget when you compare quantum computing with DNA sequencing or image recognitions is that quantum computing is at the bottom of current theoretical paradigm. When you do DNA sequencing the science of your instruments (eg. centrifuges) is not suspect. In QC everything is suspect; your system, your detection mechanisms, your control systems. If you normalize every field by its fundamental difficulty you will find that quantum information is keeping up with other fields.