Will Dr. Scott Aaronson at UT Austin please chime in ?
Quantum Supremacy Using a Programmable Superconducting Processor
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Re: Quantum Supremacy Using a Programmable Superconducting Processor
#42I'm like 99% sure Google said "what's the most contrived workload that technically counts as quantum supremacy" and went from there... That being said, we certainly live in interesting times.
Even if it's highly contrived, it's still something that they found a task for which the quantum computer is superior. It points the way towards a more general superiority where some at least have doubted the possibility.
Simulating a drop of water falling on the floor accurately at the molecular level would take thousands (if not millions) of years on the best supercomputer today.
Does it mean my water dropper is a better physical computer than regular computers?
Re: Quantum Supremacy Using a Programmable Superconducting Processor
#43To me this reads a lot like “quantum computer faster than a classical computer at ‘simulating’ itself”. Constructing a physical experiment where it would take a classical computer 10000+ years to simulate the outcome is trivial. I don’t see how this is very different.
There is a slight difference, that really matters to theoretical computer scientists (as in complexity theory) and physicists working on quantum computing: The challenge is to construct a physical experiment that consists of only 50ish "elementary" and "programmable" building blocks that is infeasible to simulate on a classical computer. This "universality" and small number of elements is what is exciting and what ma…
The difference seems to be that if it's just 'simulating itself' as the top level comment described, then it is a really bad demo of the universality that would be so exciting.
Re: Quantum Supremacy Using a Programmable Superconducting Processor
#44Why is quantum supremacy important ?
Quantum supremacy is reached when a quantum computer does something that no classical computer can do.
So before quantum supremacy, quantum computers are useless.
Which does no mean that after quantum supremacy quantum computers are useful. Usefulness depends on people, is a social property. We need to be able to solve a problem relevant to humans.
There is reasonable hope that with more (quantum) computing power and people ingenuity we will be able to make quantum computer useful.
Actually, many (among them investors) think that quantum computing is a turning point in human history.
Re: Quantum Supremacy Using a Programmable Superconducting Processor
#45“Supremacy” is a descriptor various parts of government use when they need funding. The implication is that achieving “supremacy” with some hot area of global security requires spending $X, and if $X _aren’t_ spent, then we will be behind. No one wants a quantum gap!
While the choice of the word is indeed regrettable, it has nothing to do with your guess or with any national security topic. See the sibling comment https://news.ycombinator.com/item?id=21044196
I stand corrected. Thank you.
Quantum computing is, like blockchain and AI, a topic that’s fretted about in the NatSec establishment, often by those who don’t understand the topic in depth but are otherwise NatSec experts and help control resources. “AI Supremacy” is a book in that vein; Kai-Fu Lee’s book has freaked out many others.
Re: Quantum Supremacy Using a Programmable Superconducting Processor
#46These seem to be much stronger claims than were made last time this was discussed: ”””While our processor takes about 200 seconds to sample one instance of the quantum circuit 1 million times, a state-of-the-art supercomputer would require approximately 10,000 years to perform the equivalent task.””” ”””Quantum processors based on superconducting qubits can now perform computations in a Hilbert space of dimension 2^5…
Yes, quantum supremacy disproves the extended church-turing thesis (Bernstein-Vazirani). This thesis states that any computation that can be computed efficiently can be computed efficiently with a classical computer (ie a Turing machine).
ECT thesis means that quantum computers will never be able to compute something significantly faster that classical ones.
However, technically, google haven't proved yet quantum supremacy since they just did the classical calculation using the best known classical algorithm. And there is no proof that there is no significantly better algorithm.
But this not a serious objection, no one thinks that there is an exponentially better way of classically simulating quantum computers.
Re: Quantum Supremacy Using a Programmable Superconducting Processor
#47What's the chance someone will come along with a classical analog that matches/beats this result? I remember seeing claims of quantum supremacy in the past and then clever people invented new classical algorithms that performed just as well.
No, "quantum supremacy" is a technical term that has not been achieved before, and has not been claimed to be achieved by anyone serious. You may be misremembering previous claims called something different.
I guess you're right, I remember seeing quantum algorithms that were assumed to be more efficient than any classical algorithm and then people devised equally efficient classical algorithms. E.g. work by Ewin Tang https://arxiv.org/abs/1811.00414
Re: Quantum Supremacy Using a Programmable Superconducting Processor
#48Why is quantum supremacy important ? Quantum supremacy is reached when a quantum computer does something that no classical computer can do. So before quantum supremacy, quantum computers are useless. Which does no mean that after quantum supremacy quantum computers are useful. Usefulness depends on people, is a social property. We need to be able to solve a problem relevant to humans. There is reasonable hope that wi…
Quantum supremacy was mainly coined as a milestone as a response to certain vocal famous people (almost none physicists, which was the problem) who have been skeptical about quantum computers at a fundamental level. That is to say, there is something in the nature which will always forbid the quantum speed up (as in the case of perpetual motion machines) however you design a quantum computer.
Those certain individuals have publicly kept debating against it for years, from basically claiming that quantum computation is snake oil to moderate skeptical positions and kept saying either quantum computers can't do anything beyond the capabilities of classical computers (in terms of complexity) or that it's outright impossible to build one. For decades. (Some of those ramblings have appeared on news outlets and here as well as top news.)
Physicists of course know that quantum speed up is real (which is why Feynman proposed it, and why there are so many working on this, and so much money is being poured into it) and that it is an "engineering" problem (albeit a very non-trivial one in uncharted waters) to build a device which can make use of it.
Such experiments, although not of any practical use for people, are important to establish certain fundamental facts about nature in a way everyone (including people from other disciplines) can understand without studying quantum mechanics and the physics of the devices.
Re: Quantum Supremacy Using a Programmable Superconducting Processor
#49Earlier quoted context omitted.
Even if it's highly contrived, it's still something that they found a task for which the quantum computer is superior. It points the way towards a more general superiority where some at least have doubted the possibility.
Simulating a drop of water falling on the floor accurately at the molecular level would take thousands (if not millions) of years on the best supercomputer today. Does it mean my water dropper is a better physical computer than regular computers?
This is to the point. The universe is a giant big computer even without quantum involved. If the starting state of the computation is not predefined, the so-called computer is no difference from randomly flipping some coins.
What the paper showed is no difference from showing the wind did not change the result of coin flipping.
Re: Quantum Supremacy Using a Programmable Superconducting Processor
#50To me this reads a lot like “quantum computer faster than a classical computer at ‘simulating’ itself”. Constructing a physical experiment where it would take a classical computer 10000+ years to simulate the outcome is trivial. I don’t see how this is very different.
To call these things computers is a stretch anyways. So far they are simply very regularly arranged controllable quantum widgets.
They're as much of computers as analog computers are.