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Hardware Technology

Quantum Computing Without Qubits 81

An anonymous reader shares this interview with quantum computing pioneer Ivan Deutsch. "For more than 20 years, Ivan H. Deutsch has struggled to design the guts of a working quantum computer. He has not been alone. The quest to harness the computational might of quantum weirdness continues to occupy hundreds of researchers around the world. Why hasn't there been more to show for their work? As physicists have known since quantum computing's beginnings, the same characteristics that make quantum computing exponentially powerful also make it devilishly difficult to control. The quantum computing 'nightmare' has always been that a quantum computer's advantages in speed would be wiped out by the machine's complexity. Yet progress is arriving on two main fronts. First, researchers are developing unique quantum error-correction techniques that will help keep quantum processors up and running for the time needed to complete a calculation. Second, physicists are working with so-called analog quantum simulators — machines that can't act like a general-purpose computer, but rather are designed to explore specific problems in quantum physics. A classical computer would have to run for thousands of years to compute the quantum equations of motion for just 100 atoms. A quantum simulator could do it in less than a second."
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Quantum Computing Without Qubits

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  • I have this impression of "quantum simulator" analog computers, that if you want to make them truly capable, you have to give them the ability to blow up by overloading themselves, sort of like blowing an amp. Comments?
    • by Anonymous Coward

      The proposal for the quantum simulator was made back in 1982

      In 2011 paper was already written about the matter

      http://arxiv.org/abs/1109.6457 [arxiv.org]

      • One of the other doctoral students that shared an adviser with my dad built an analog circuit simulating Schrodinger's equations hydrogen atom solution back in about 1960. I doubt he was the first. People have been working on this kind of thing for a long time.

  • by Anonymous Coward

    Look in the sky, see the flock of starlings?
    The dark clump of birds that you can see will dart around, sometimes here, sometimes there. It can fly west and yet clump east, time-travel! Must be negative time! Sometimes simultaneously appearing in two places. Faster than light travel! Sometimes no clump can be seen. Where'd they go? Poof, out of existence.

    You want a quantum simulator? Starlings, go watch a flock of starlings and apply your quantum equations to their motion.

    You may think I'm kidding, but the

    • by clovis ( 4684 ) on Friday January 23, 2015 @12:51AM (#48882319)

      Look in the sky, see the flock of starlings?
      The dark clump of birds that you can see will dart around, sometimes here, sometimes there. It can fly west and yet clump east, time-travel! Must be negative time! Sometimes simultaneously appearing in two places. Faster than light travel! Sometimes no clump can be seen. Where'd they go? Poof, out of existence.

      You want a quantum simulator? Starlings, go watch a flock of starlings and apply your quantum equations to their motion.

      You may think I'm kidding, but the same problem exists. Just as you can't see the individual bird, only the flock, likewise you've built a bunch of equations for a flock of smaller particles. You can only detect the flock and not the particles.

      Keeping with your analogy ... In order to exactly determine the location of each single starling, you need a shotgun(s). Then it no longer is part of the flock now that it has been observed.

      As an aside, I am aware that you can shoot at a flock of starlings all day and not hit a one.

      • by Anonymous Coward

        And if you fly two flocks into each other at the right velocity, for a moment you can see them fly in what we experts calls a 'Higgs Boson' formation!

        But there is a risk of catastrophic bird poop aftermath. Who knew that dark matter would smell so bad.

        • But there is a risk of catastrophic bird poop aftermath. Who knew that dark matter would smell so bad.

          Not Who, just who [wikia.com]

          • by Bob_Who ( 926234 )

            But there is a risk of catastrophic bird poop aftermath. Who knew that dark matter would smell so bad.

            Not Who, just who [wikia.com]

            Say what..?

        • by jcwayne ( 995747 )

          ...and then have the laser toting sharks surround them and they'll form a Bose–Einstein flock condensate.

    • by cowdung ( 702933 )

      what the flock are you talking about?

    • by Anonymous Coward

      Seriously, though, if you observe the flock in location A, the birds at location B don't suddenly cease to exist. In QM they would. Also the density of the flock is a real scalar, the density of the wave function is a complex number.

  • by m.alessandrini ( 1587467 ) on Friday January 23, 2015 @01:21AM (#48882399)
    ... if you know the computer's speed, you cannot know where the computer is.
    • Re: (Score:3, Informative)

      by Tablizer ( 95088 )

      It's like Microsoft or Comcast products: they can never be up running and be reliable at the same time.

      • by Bob_Who ( 926234 )

        It's like Microsoft or Comcast products: they can never be up running and be reliable at the same time.

        ....or can't be purchased or paid in full... you just pay forever and its never yours.

  • by Qubit ( 100461 ) on Friday January 23, 2015 @01:45AM (#48882449) Homepage Journal

    I would've preferred "Noble Steed," but I'll take it.

  • by WaffleMonster ( 969671 ) on Friday January 23, 2015 @01:45AM (#48882451)

    I don't believe in real quantum computers because they require operating on the premise you can just sit there and extract whatever unlimited amounts of computation from the universe for a cost exponentially approaching free.

    No doubt at all these machines given enough time and effort will work and they will provide the world with useful benefits only those benefits will look nothing like:

    "Problems that would take a state-of-the-art classical computer the age of our universe to solve, can, in theory, be solved by a universal quantum computer in hours."

    • Re: (Score:2, Informative)

      by Anonymous Coward

      require operating on the premise you can just sit there and extract whatever unlimited amounts of computation from the universe for a cost exponentially approaching free.

      I don't believe in whatever you're talking about either, but that has nothing to do with "real" quantum computers. There are still limits what they can computer, especially energy limits. They may allow for algorithms with different complexity classes than classical computers, but they don't approach unlimited amounts of computation, especially at diminishing costs.

    • I don't believe in real quantum computers because they require operating on the premise you can just sit there and extract whatever unlimited amounts of computation from the universe for a cost exponentially approaching free.

      No, they don't.

    • Quantum computers is to computing what digital computers are to abacuses.

      Theres no major breaking-the-laws-of-physics going on, its just a different way to carry out computations, one that has taken us a while to create - but it took us thousands of years to go from abacuses to digital computers, so give us time.

      Your view of quantum computers is exactly what I would expect to hear from an Egyptian accountant back in 500BC experiencing a hand held calculator for the first time. Doesn't make a hand held calc

    • by Tablizer ( 95088 )

      Those chips will use up all the parallel universes, and then I'll never get laid, anywhere, you insensitive clod!

  • I suppose naming analog computers quantum simulators somehow renders them hip and more useful than just calling them analog computers.

    • Just what I was thinking. I'm not expert on quantum computing (but who is?), but I think an analog computer simulates an analog system, or at most another analog computer. About a quantum computer, isn't it impossible to simulate, due to its very nature? Unless you count the qubits that mother nature has built for us in every particle, and so every single particle evolving in the universe can be seen as a quantum computer simulator.
  • Einstein never really accepted quantum mechanics. I sometimes wonder if the issues regarding quantum computing are a little more fundamental than technological. Maybe that old genius was smarter than we give him credit for!
  • > A classical computer would have to run for thousands of years to compute the quantum equations of motion for just 100 atoms.

    But is it web-scale?
  • I noticed a lot of posts proclaiming quantum computers will never exists, but they actually already do exist: In 2001, researchers demonstrated Shor's algorithm to factor 15 using a 7-qubit NMR computer.(http://en.m.wikipedia.org/wiki/Quantum_computing) Just because the next advancement is hard doesn't mean it's impossible. We've gotten so accustomed to a limited set of technology improving we've lost our sense of how long it takes to solve entirely new classes of problems. Think how long modern computers
    • The problem is how well solutions scale. Give me 7-bit classical processors, and I can eventually hack them into something bigger. Two 7-qubit quantum processors can't be used to create a 14-qubit one, and making a 14-qubit processor is a whole lot harder than making a 7-qubit one. We're doing better at building these, but it's possible we'll never be able to make, say, a 10K-qubit computer, without running into some limit somewhere, and some proposed uses require that many qubits.

      We'll have to see.

  • by Geoffrey.landis ( 926948 ) on Friday January 23, 2015 @10:28AM (#48884641) Homepage

    "A classical computer would have to run for thousands of years to compute the quantum equations of motion for just 100 atoms. A quantum simulator could do it in less than a second."

    ...and a hundred atoms can do it in real time!

"An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup." - H.L. Mencken

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