The chips we make (speaking directly of D-Wave, but afaik this is true of all superconducting QC efforts) would cost pennies if we produced them at scale. But the surrounding machinery is extremely complex, and very expensive to manufacture -- and scale would only get you so far. My rough understanding of refrigeration is that the temperature differential strongly depends on the length of the heat exchanger. Qubits are famously sensitive to noise; and blackbody radiation gives an inescapable dependence between noise and temperature. In short, a miniaturized fridge would be necessarily hot, and therefore too noisy to perform quantum computation!
So the sad news is that, barring some major developments, we may never have miniature quantum computers. In the foreseeable future, hardware costs will be measured in millions of dollars. So even if you're a millionaire, you probably don't want to buy a quantum computer. If you work for a university, a national laboratory, or a major corporation, you might try to convince your organization to purchase a quantum computer. If you succeed in that pitch, you'd almost certainly need to share it with your colleagues over a network.
So to me, an industry insider, it feels that public access to quantum computing is almost necessarily QCaaS.
We couldn't possible foresee how these monster of a machines could possible fit in the palm of our hands and yet, now, it's hard to see how we couldn't see that far in front of us.
We had this famous quote from IBM but, I wonder if as an industry this was a common perspective. Or wether between those who were building these machines could foresee where we'd be now? Is there some one in Quantum Computing who has the intelligence and creativity to think, nah, we'll have giant refrigerated quantum computing mobile phones in 5x decades time (I understand Quantum Computers wouldn't make great phones I'm just drawing baseless comparisons :) )
"I think there is a world market for maybe five computers."
Thomas Watson, president of IBM, 1943
= = = =
I only found out about wolframalpha a month ago and I'm still in awe of it. Quantum computing as a service? No idea what I'm going to want to do with it. But I re-watch this video by Veritasium and Andrea Morello from UNSW a couple of times a year to just remind myself how much I don't know.
Even if he had said it, it was a very accurate statement at the time. Gordon Bell has noted that at the time he is claimed to have made that statement, it would have held essentially true for a decade. As something that would have likely been said (if said at all) in discussions around IBM's near-future business plans, or a sort of market analysis of the conditions at the time, it makes perfect sense.
That said, LH2 temperatures aren't really hard and can easily fit in a 2U rackmount device, providing power/classical-RF uses of type2 superconductors. Think EMI shielding, power conditioning, ~50 GHz traces that can span a full backplane without fancy signal conditioning, etc.
It is very hard to dissipate heat from a solid object into space. This is not true for our bodies on the other hand, but that is more to do with pressure - if you expose cells to the Void of space, most liquids inside would quickly expand in size and essentially boil, consuming large amounts of heat to go through the phase transition from liquid to gas, thus quickly cooling surrounding tissue. You could theoretically use this to create evaporation-based heating, but you would have to transport vast quantities of water that would quickly be used up, since there is no hope of collecting them back most likely.
I’m fairly sure decades ago people assumed we may never have tiny computers in our pockets with the same certainty you have now.
This is what it means to be crazy enough to change the world.
Oh, and fusion reactors.
Now that I think of it, there was a lot of variation in predictions of computing. But I would say that it's been pretty common for science fiction to describe technology 30 years out somewhat accurately, probably because it has inspired the actual tech in a self-fulfilling way.
So, in the 40s, a spaceship was envisioned able to carry only calculators and slide rules, with a radio link to a big central computer. That wasn't far off of how things developed in the 60s and 70s. But I think by the 60s and 70s, people were imagining pocket computers and tablets and such and that had a huge effect on people actually designing them when it was possible.
By no means do I intend to discourage progress! I wouldn't do the work that I do if it wasn't so difficult. I did hedge, a bit: "may never," "foreseeable future," "without major developments."
The fridge is just one major obstacle. There's a plethora of physics, engineering, and mathematical challenges out there impeding progress. Get to work!