Google has enlisted NASA to help it prove quantum supremacy within months, Technology Review
“Quantum supremacy is the idea, so far undemonstrated, that a sufficiently powerful quantum computer will be able to complete certain mathematical calculations that classical supercomputers cannot. Proving it would be a big deal because it could kick-start a market for devices that might one day crack previously unbreakable codes, boost AI, improve weather forecasts, or model molecular interactions and financial systems in exquisite detail. The agreement, signed in July, calls on NASA to “analyze results from quantum circuits run on Google quantum processors, and … provide comparisons with classical simulation to both support Google in validating its hardware and establish a baseline for quantum supremacy.”
NASA/Google Space Act Agreement

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7 replies on “Google And NASA Ames Seek "Quantum Supremacy"”

  1. That is a terrible quote. There is, at this time, no known problem that a quantum computer can solve that a classical computer cannot. Finding such an example would be a massive breakthrough in computer science. But it is not believed to be possible. It’s a fundamental axiom of computer science that ALL computable processes can be simulated by a turning machine, and a real computer can simulate a time-space bound Turing machine, so a computer can compute anything. We think.

    This article is claiming that NASA and Google are looking to build a quantum computer that “will be able to complete certain mathematical calculations that classical supercomputers cannot.” That’s NOT what is going on here. They’re attempting to build a quantum computer big enough and fast enough to solve certain specialized but meaningful problems faster or more efficiently than a classical computer can. But “cannot efficiently do” and “cannot do” are two very different things.

  2. So the underlying assumptions about the ability of quantum devices is this: a problem that cannot be solved in a quantitative way is resolved by examining in turn every possible solution.

    Relying on analog techniques to resolve digital problems. At the least it is ironic.

    I like it.

    1. Not exactly. I’m not an expert on quantum computing, but quantum anything pretty much implies digital (discrete states) not analog. I think one of the important difference is that normal computers have a 1 or a 0 (or true and false), whereas a quantum computer could handle a 42% chance or 1 and a 58% chance of 0. In other words, it’s either true or false (no grey area), but the quantum computer wouldn’t need to be sure which it is. You could do the same thing with a conventional computer, but it would take slow and complicated software to get the same result. You’d be fighting against the basic, binary logic conventional computers are built around.

      And I think Mr. Friedenbach’s comment about Turing’s Completeness Theorem is correct. If it’s Turing complete, which almost all modern computers are, it should be able to do any sort of calculation you like. But Turing’s theorem doesn’t say it could do it in less than the age of the universe.

      1. I’m not a quantum computation specialist. But I am a computer scientist, applied physicist, and cryptographer who has to keep abreast of advances in quantum computation advances as they apply to my field.

        I think it is actually rather accurate to call quantum computing “analog” computation. Quantum computers work by building special-purpose networks for the interaction of entangled particles where quantum effects cause incorrect solutions to destructively interfere and valid solutions constructively overlap, strengthening in magnitude. It’s like if you wanted to test primality by setting up a sequence of prisms and mirrors to refract, reflect, and filter light such that the resulting spectra has lines spaced at prime number intervals (by filtering out the composites via a physical sieve). It’s the first time I recall hearing quantum computation described as analog, but I think it’s very apt.

        For the record, no quantum computer is Turing complete or anything like that. It’s an open research question as to whether there is even anything we might reasonably call a “generalized quantum computer” in the way a Turing machine is a general classical computer. All quantum computers studied today are special-purpose machines designed to solve parameterized instances of specific problems. For example, Shor’s algorithm solves integer factorization in polynomial time, and Grover’s algorithm searches an unordered list in sublinear time. These aren’t software algorithms you run on a quantum computer, but specific hardware circuits that are only programmable in the sense of specifying the integer to factor and the pair of list and search term.

        1. It still isn’t quite a massively parallel analog simulation. Commonly referred to as an experiment!

        2. I see your point. I’m thinking in terms of quantum states, which are discrete and therefore essentially digital. You’re thinking in terms of the probability of particles being in one state or another, and the probability of transitions between those states. That’s a continuum and I guess that makes it analogue. This is starting to sound like the whole business about whether light is a wave or a particle. At this point, I think I’ll just drop this.

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