Tuesday, January 16, 2018

Quantum Computers Throw Some Confusion at Buyers

A little short of five years ago, I ran a piece about a player in the quantum computer field called D-Wave Systems.  It included this little tidbit.
Dr. Ladizinsky talks about the fact that in his quantum computer, a loop of super cold niobium wire has all of its electrons going in one direction and at the exact same time the same piece of wire has all of its electrons going in the opposite direction.  Their niobium wire is exhibiting quantum behavior in a macroscopic object.
For illustration, assume current in one direction is a logic "0" and current in the opposite direction is a "1".  The superposition of two different states at the same time is what constitutes a qubit, or quantum bit, and creates quantum computing.

In the intervening five years, quantum computing as entered into field trials.  D-Wave has sold systems to Lockheed Martin, NASA, the NSA (National Security Agency), and Google, each of which paid somewhere between $10 million and $15 million for the system.  Recently, D-Wave committed some of the important software they've been developing to open source.  The only problem is that the buyers aren't sure that they actually bought a quantum computer.  It turns out that's a hard thing to prove.
These machines are of little use to consumers. They are delicate, easily disturbed, require cooling to just above absolute zero, and are ruinously expensive. But the implications are enormous for heavy number-crunching. In theory, banks could use quantum computers to calculate risk faster than their competitors, giving them an edge in the markets. Tech companies could use them to figure out if their code is bug-free. Spies could use them to crack cryptographic codes, which requires crunching through massive calculations. A fully-fledged version of such a machine could theoretically tear through calculations that the most powerful mainframes would take eons to complete.

The only problem is that scientists have been arguing for years about whether D-Wave’s device is really a quantum computer or not. (D-Wave canceled a scheduled interview and did not reschedule.) And while at some level this doesn’t matter—as far as we know, D-Wave’s clients haven’t asked for their money back—it’s an issue of importance to scientists, to hopeful manufacturers of similar machines, and to anyone curious about the ultimate limits of humankind’s ability to build artificial brains.
Surely it can't be that hard right?  Why not take it apart and probe it?  Or why not run a sample computation, a benchmark if you will, on it and another computer to see which is faster.  Unfortunately, it's not that easy.  It violates the laws of quantum physics to be able to look inside (probe it), so the system can't be probed.  When a quantum system is observed, it collapses to one state or the other.  In the example from the original  paragraph, if one measures the current flow in any of the 512 niobium wire loops it will only appear to be moving in one direction, not both.  This is collapsing the Quantum Wave Function - made famous by the analogy Erwin Schrodinger proposed about a cat that is simultaneously fully alive and fully dead.
The controversy surrounding D-Wave is rooted in the fact that the company doesn’t claim to have built a full-fledged “universal quantum computer” that can tackle any problem. In particular, it doesn’t claim to able to crack secret codes; if it did, the argument would be over quickly. The technique it uses, called “quantum annealing”—which we won’t even try to explain—is only good for solving specific sorts of mathematical puzzles called optimization problems. As their name implies, these involve finding the quickest or lowest-cost way to do something. (That could make the technique useful to banks and mining companies, but not spy agencies.)

The trouble is, it’s possible to build a device that produces a similar result to quantum annealing without any quantum behavior—i.e., without invoking superpositions and parallel universes. So the question is: Is the D-Wave machine doing quantum annealing, or just something that looks like it? And this is where things get tricky.
Researchers can't look into it, and they may not even be able to test its speed.
Even if there were a speedup, it would be hard to measure. There was a good deal of hype about an experiment last year by a scientist whom D-Wave had hired as a consultant, showing that the D-Wave 2 did a certain calculation 3,600 times faster than a conventional machine. But as it turned out, the likelier reason the conventional computer was slow was that its software was slow. Other researchers said they’d been able to make an ordinary laptop, using different software, run as fast as the D-Wave.

Even D-Wave admits that in its work with Google, it’s machines were only “comparable or slightly better” than conventional computers. Google wrote on its research blog a year ago that it has been able to do some interesting things with its D-Wave, but carefully avoided claiming that they were things only a quantum computer could do.
It ends up being fundamentally hard to answer the question of whether or not the D-Wave Systems boxes really are quantum computers, and the whole article is worth reading. 
In this recent photo, we find that Schrodinger's cat learned to create a quantum superposition of kibbles in each of the parallel universes it visited, so that alive or dead, it had an unlimited supply of kibbles.  Photo from the Quartz article. 

If you're waiting for me to reveal if the D-Wave Systems box really is a quantum computer, the Quartz article doesn't say conclusively.  We could say it exists in the superposition of states of simultaneously being and not being a quantum computer.  They point out that Michele Mosca, a co-founder of the Institute for Quantum Computing at the University of Waterloo in Canada, says that the very meaning of the words “quantum computer” is fuzzy. He proposes five (actually five-and-a-half) definitions, which are listed at the bottom of the Quartz article for the technically minded.
The D-Wave, Mosca says, definitely meets definition 2, and probably its stronger variant, meaning that it is behaving somehow differently from classical computers, but not necessarily faster. If further research can show that it meets definition 3, that means it can be faster than classical machines at certain tasks, provided the problems aren’t too large. If it meets definition 4 (the best, Mosca says, that it aspires to) then it has the potential to continue to be faster for any larger, more complex input —though again, only for certain tasks.

That would still be hugely important. It would mean that the D-Wave is taking advantage of the weird properties of quantum physics to do things that, until not so long ago, were thought literally impossible, and open up the ability to solve problems that would otherwise remain out of reach.

But the full power of a quantum computer will be realized only when a machine can satisfy definition 5—a general-purpose device that far outstrips conventional computers at any task they can perform. That machine has not yet been built.
If the D-Wave is not a quantum computer that raises perplexing questions.  It raises questions of whether or not they know what they're doing, if they knowingly sold fakes, or unknowingly sold fakes (that is, they were faked out themselves) and if the buyers are thinking they bought fakes.  


  1. I do not think that D-Wave is genuine quantum computing, but it's an incremental step in that direction. They are taking advantage of the weird science of quantum mechanics, which is cool and is useful. Whether it's worth the cost in the world of private enterprise is up to the buyer. Schrodinger's cat needs to stop munching that kibble in the fourth dimension.

  2. Updated - List of companies giving bonuses, pay raises and 401K increases continues to grow! - thanks to Trump Tax Reform Bonuses


    1. Now we need a list of Democrats, Media, and Koch-sucking Rove Republicans who are still insisting that the tax bill is the ruination of the middle class...

  3. There are two major problems with the whole "quantum computing" field.
    1. Human minds don't work well with this sort of "logic". Normal computers are difficult enough to program accurately. See, for example, the early Pentium processors, and the recent problems with Spectre and Meltdown.

    2. Quantum computing is based entirely on the Copenhagen interpretation orthodoxy, which is simply wrong, and has held back science for decades. What people don't understand is that Schroedinger was mocking the interpretation with his "cat in a box" thought experiment.

    Equal currents in both directions on a wire sounds an awful lot like no current at all. Alternatively, and slightly more usefully, there may be some random level of current in some random direction, but strength and direction are both random and unknown until measured. Random signals are slightly more useful than a complete lack of signals, but not by much. Unless you are building a random number generator, in which case this sounds perfect. But that's probably all it's good for, and will eventually show some bias if run long enough.

    1. For those who may not know, the Copenhagen interpretation of quantum effects can be restated thusly: If you roll a die and it falls off the table and bounces behind the bookcase where you can't see it, the die doesn't have any actual value. The die definitely doesn't show a single face which you, the observer, simply can't see and thus don't know. Instead, the die shows all six faces equally. Only when you move the bookcase so you can see the die, does it suddenly (and randomly) choose a side to show you. Until the moment you looked, there was no definite facing.

      The Copenhagen interpretation is scientific hubris at its finest - until a scientist looks at something, it doesn't definitely exist.

    2. So THAT is where Global Warming comes from!

    3. McChuck:

      Years ago, I was waiting for a package to be delivered and realized it was the same as a quantum wave function. Is the package in the mailbox? Without observing I don't know, so while I could say it's either there or it isn't, I can use the same words about the box we say about quantum wave functions: it's simultaneously there and not there until I look. When I open the mailbox, I collapse the QWF and it goes to one state or the other. There OR not there.

      It's entirely centered on the observer.

      I see descriptions of Heisenberg uncertainty (we can know the position or the velocity of a particle but not both) as if it's some sort of bizarre thing, but it's something every photographer knows. Take a picture of a moving car. You either use a fast shutter speed and see exactly where it was at that millisecond (or less), or use a longer shutter speed and get a blur - you can't see the exact position - and from the blur you can tell the speed.

      The idea that we can get useful problem solving out of a system where, as you say, no current is flowing is one I'm really skeptical about.

      If one was a con man, what better thing to sell than something that buyers can't test, can't observe and can't prove it really is what's being sold.

    4. It does rather smack of the Emperors new clothes. It's super-duper and really good but we can't prove it anjd you can't test it. But it is fantastic (i.e. that which is based on fantasy or so fantastic to be untrue).

      OK, joking aside, the quantum world is a weird and wonderful place and the effects are measurable but as McChuck said, two equal and opposite flowing currents equal the square root of nothing ...

      Unless the computers were benchmarked against the known performance of an existing computer running identical software, I'll keep my cash in my pocket.

      Phil B

    5. My understanding of Heisenberg is that the uncertainty is like claiming you have an audio tone of 440 Hz for a duration of 1 nanosecond. When you try to get too small with one measurement (duration), the other measurement (frequency) gets undefined.

      My understanding is that QM interpretations are made-up fiction stories, because the experiments don't tell you if the "interpretation" is true. Superposition? Many-universes which split? The experimental results don't give guidance on the possible implementations.

  4. Anonymous at 2018/1/17/21:50 - Yep, pretty much. It also has the side benefit of defining a minimum energy, distance, and time. https://infogalactic.com/info/Planck_constant#Uncertainty_principle

  5. Most physicists of the 1920s were struggling to explain quantum effects in non quantum terms. Well, and as McChuck said, a large does of Hubris.

    Most problems people have with Quantum theory have to do with not wanting to admit that things are very weird at the subatomic level. And the people studying it are a bit weird too. (I did a summer internship in the nuclear structures group at a National Lab. so I know of which I speak.)

    I leave this for your contemplation. https://youtu.be/2rjbtsX7twc