Wednesday, July 23, 2014

Aaronson sarcastic about quantum info in 2040

Scott Aaronson writes an article on How Might Quantum Information Transform Our Future?:
Picture, if you can, the following scene. It’s the year 2040. You wake up in the morning, and walk across your bedroom to your computer to check your email and some news websites. Your computer, your mail reader, and your web browser have some new bells and whistles, but all of them would be recognizable to a visitor from 2014: on casual inspection, not that much has changed. But one thing has changed: if, while browsing the web, you suddenly feel the urge to calculate the ground state energy of a complicated biomolecule, or to know the prime factors of a 5000-digit positive integer — and who among us don’t feel those urges, from time to time? — there are now online services that, for a fee, will use a quantum computer to give you the answer much faster than you could’ve obtained it classically. Scientists, you’re vaguely aware, are using the new quantum simulation capability to help them design drugs and high-efficiency solar cells, and to explore the properties of high-temperature superconductors. Does any of this affect your life? Sure, maybe it does — and if not, it might affect your children’s lives, or your grandchildren’s. At any rate, it’s certainly cool to know about. ...

As magical as it all sounds, this is the wondrous science-fiction future that my sixteen years of research in quantum computing and information lead me to believe is possible. Assuming, of course, that we actually do build scalable quantum computers.
So even if scalable quantum computers are invented, the impact on our lives will be negligible.

I guess he is being sarcastic here, so it is hard to tell whether he thinks quantum computers will ever be possible, or whether he is making fun of those who do. He alternates between over-hyping the subject, and criticizing those who do.

Predicting the future is tricky, of course, but computer technology has been on a stable predictable path for a long time. Processing power has followed Moore's Law for 50 years. Artificial intelligence, such as voice and image recognition, has progressed more or less on schedule. Some say that we are headed for the Singularity around 2040. That seems optimistic to me, but they are not even assuming quantum computer benefits.

But there is still no experiment demonstrating that quantum computers are feasible, and I doubt that there ever will be.

I agree with Gil Kalai:
I find the article entertaining and enjoyable in spite of me being one of the “skeptics” who think that superior computation through quantum computers is not possible. (And I really mean “not possible” :) .) ... Of course, impossibility of computationally superior quantum computing is not in conflict with quantum mechanics.
Even if quantum computers are possible, the main application will be destructive -- breaking our current computer security and requiring complicated and expensive work-arounds to achieve what is easy today.

Aaronson adds:
To be honest, I have no idea whether QKD will ever find a significant market or not. But at least the technology already exists (and “works,” over short enough distances), if a nontrivial market were ever to develop.

It’s true that there are classical cryptosystems that are probably secure even against quantum computers. However, the trouble is that all such systems currently known are either
(a) private-key, and hence cumbersome to use, or else
(b) public-key systems like the lattice-based systems, which currently require key sizes and message sizes large enough to make them impractical for most applications.

Of course, it’s possible that more practical quantum-secure public-key cryptosystems will eventually be discovered. Certainly lots of people have been thinking about that. But if no such systems are discovered, and if (on the other side) the technology of QKD were to improve so that it could handle much higher bit-rates and distances, then there really could be a good use case for QKD.
Quantum key distribution will probably never have any practical utility. Sure it works, but much simpler methods give much better security.


  1. The aaronson carnival barker is nuts again. At least I know what the Motl goof's motivation for endorsing the rubbish that is the Copenhagen interpretation (CI): the useless reductionist dogma of CI is required for his string theory baloney. The correct 'minimalist' interpretation of quantum theory is incompatible with the reductionistic point of view.

  2. Look what this quantum "bigwig" said a few posts ago in 'Carroll goes nuts with many worlds'

    'On Quantum Theory' by Berthold-Georg Englert:

    "For that to have any
    meaning, the existence of events must be accepted in the
    first place. In this sense, then, the event is a preexisting
    concept of quantum theory. We cannot formulate the theory
    without this concept."

    Hahaha...the QM is all about this crazy notion of the 'event'?

    All applications of quantum mechanics applied to genuine single events should lead to absurd consequences. This is exactly what happens. The long list of absurdities and paradoxes resulting from the braindead Copenhagen Interpretation single-event point of view includes, as prominent members, the measurement problem, the Aharonov-Bohm effect, and cause-effect velocities exceeding that of light.

    And that Englert idiot says the event is fundamental? There was analysis of tunneling data where signal velocities up to five times the velocity of light were found Sorry numbnut Englert, but single (microscopic) events are out of our reach. Many-body systems behave (fortunately) effectively like statistical ensembles and this explains the enormous success of quantum mechanics and its relevance for the macroscopic world.

    I can't believe these idiots like Motl and Englert. They are useless text-book regurgitators and they understand nothing at all about quantum theory.

  3. Copenhagen Garbage

    1. Wave-Particle Duality

    Complete rubbish. Wave-like behavior occurs only as a consequence of the collective behavior of a large number of elementary particles and has never been observed by looking at individual events. Nothing wave-like is discernible in the arrival of single electrons at the observation plane. It is only after the arrival of perhaps tens of thousands of electrons that a pattern interpretable as wave-like interference emerges. Therefore, individual particles are always particles and never waves


    Far better than the copenhagen garbage.

  5. Roger, admit and Motl with your copenhagen garbage are being swept aside:

    The many-worlds interpretation should probably be called something more like "many histories". I like it, because it completely avoids the awful notion of the wave function collapsing, and denies any role whatsoever to measurement, consciousness, etc. And it makes the success of quantum computers remarkably sensible, which I don't think we can say for any of the other interpretations. The only exception I can think of is the Ithaca interpretation, which merges very nicely with many-worlds. This is, roughly, the idea that the wave-function is a real, objective thing, as are correlations between systems, and that "measurement" is just a particular case of decoherence

  6. Too much 'Anonymous' going on. At least identify yourself as something, take a chance that your opinion might be associated with you. If several people are going to be calling themselves 'Anonymous' then discussion is impossible.