Slashdot Mirror
First Evidence That Google's Quantum Computer May Not Be Quantum After All
KentuckyFC writes "In May last year, Google and NASA paid a reported $15 million for a quantum computer from the controversial Canadian start up D-Wave Systems. One question mark over the device is whether it really is quantum or just a conventional computer in disguise. That's harder to answer than it sounds, not least because any direct measurement of a quantum state destroys it. So physicists have to take an indirect approach. They assume the computer is a black box in which they can input data and receive an output. Given this input and output, the question is whether this computing behavior can be best reproduced by a classical or a quantum algorithm. Last summer, an international team of scientists compared a number of classical algorithms against an algorithm that relies on a process called quantum annealing. Their conclusion was that quantum annealing best reproduces the D-Wave computer's behavior, a result that was a huge boon for the company. Now a group from UC Berkeley and IBM's Watson Research Lab says it has a found a classical algorithm that explains the results just as well, or even better, than quantum annealing. In other words, the results from the D-Wave machine could just as easily be explained if it was entirely classical. That comes on the back of mounting evidence that the D-Wave computer may not cut the quantum mustard in other ways too. Could it be that Google and NASA have forked out millions for a classical calculator?"
I am at such a loss of understanding what exactly quantum computers are and how they work (no matter how hard I try)... so it makes me feel like less of an idiot when I find out that it's so complicated that even Google engineers aren't even sure if what they have IS one.
the best computer ever !
"Cut the quantum mustard" just became my new favorite catchphrase.
Why buy something that isn't demonstratively faster than the old stuff...
I mean if the difference is so small that there is some sort of debate about if it is effectively working or not, then it seems to me at that point cost should be the deciding factor. I doubt these D Wave machines are any cheaper than the old stuff.
Obviously, you don't have a use for a quantum computer if you can't find a way to determine if it's a quantum computer. If it's just speed, what you want is a super-computer. If it's the ability to perform certain calculations, they simply don't work on a classical computer (or take eternity, even for a super-computer).
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Both quantum and classical simultaneously?
captcha:conflict
Do we really think that D-Wave Systems would take that risk? They have to know that just about every major university and tech company will try to prove them wrong. Not to mention that Google will probably spend more to verify this purchase than they made on the purchase itself.
I don't know D-Wave Systems from Adam, but is this a risk they would take?
are still the future, right? Right?
Lockheed Martin also has a D-Wave system, so let's not forget that's already churning away for some three letter agency somewhere.
Google may or may not want to acquire D-Wave Systems....
If Google and NASA cannot watch the device being created, then they have to take it on faith. It is "untestable." Any attempt to test it destroys it. There are explanations favoring the quantum and explanations favoring the conventional.
I find the parallels striking what with all the money spent and all the faith required?
Maybe it simultaneously both is and isn't a Quantum computer? :-P
Lost at C:>. Found at C.
I doesn't do such a great job at "quantum computing" if the output is so close to that of a classical computer that nobody can tell which of the 2 it is?
So why does anybody care? if it were a quantum computer, it's obviously a really really crappy one, or it would've done some amazing stuff already...
You changed the outcome by measuring it!
"Have you ever thought about just turning off the TV, sitting down with your kids, and hitting them?"
I have a device for sale which generates free, unlimited power. The catch is that you cannot measure the power output or it won't function. If you put any load on the device you are directly or indirectly measuring the power, and thus it won't work. So just know up front that stipulation and use the device accordingly.
Better known as 318230.
... Google promptly returned the thousand of D-Wave devices they bought in attempt to bolster their failing conventional infrastructure. A Google representitive stated that they are looking into legal proceedings, but wouldn't comment further. A Google employee who asked to remain anonymous was quoted as saying, "What can I say? We fell for their shtick hook, line and sinker. Now we're left to pick up the pieces after the biggest technology blunder in our company's history!"
Oh, wait. That didn't happen. What actually happened is that they found some extra money between the couch cushions and bought a shiny toy to play with. I bet it won't be the last time, either.
as far as I know, there always was a lot of skepticism about D-wave being quantum computer.
so this is probably not very surprising for lots of people...
I wonder how many cats you need to feed this thing every day..
No conventional computer can replicate a quantum computer's processes. The only way to check your quantum computer's results... is to buy another one.
The original Slashdot post for the D-Wave announcement had an excellent comment: quantum annealing is NOT quantum computing, it's snake oil!
I realize the desire to tout the fact that you use a quantum computer and that if D-wave is selling a "quantum computer," they should deliver something that performs quantum computations. However, if it does what it's supposed better than other classical computers, then the money is not a waste. Unless the spending was just for show, then too bad.
what if you just look at the chip contents under a microscope? i figure if you put that much money into the company that you should be able to inspect the resulting chip. seems like it would be a simple to determine if it's just a plain ol' IC or not.
Anons need not reply. Questions end with a question mark.
How the fuck does one create a computer and then cannot even prove how the fucking thing works? What the fuck!
It doesn't matter if the D-wave machine is a quantum computer.
It matters if it can solve a useful problem better than anything else.
As far as I know, it can't.
There is only the hope that a bigger one might be able to later.
(Because is it a quantum computer which scales O(1) instead of O(2**N))
Oh, that's why it matters.
If you cannot provide a clear, watertight proof that the device actually computes stuff then you should not bother calling it a computer. D-wave is just one very expensive lottery machine. Sure it does _something_ and very _specific_ but no, it is not a quantum c-o-m-p-u-t-e-r. Having dozens of researchers and their students tinkering with the details of this little number spouting thingy is just plain regrettable.
should consider him/herself informed that models fitting data are do not constitute evidence of anything.
Especially when two supposedly incompatible (debatable) models fit the data, it just means that you don't have a clue about what is really going on. A polynomial equation of sufficient order will fit an elephant. It does not mean you have explained what an elephant is. It is not evidence of the non-parabolic-ness of an elephant.
Entia non sunt multiplicanda praeter necessitatem.
Quantum effects are not hard to understand, they're just counter-intuitive to everyday experience. This site has a good explanation of QM, and how it differs from normal experience.
The universe doesn't work in specifics until something is measured. It doesn't choose parameters for particles (spin, position, &c) at the outset and let things evolve like little billiard balls.
Instead, it uses probabilities which flow and interact with one another. These probabilities have both amplitude and phase, so that the interactions are wave-like as well as probability-like. For example, because of this wave-like interaction it's possible for two non-zero probability flows to completely cancel to zero.
The universe appears to calculate probabilities for all possible outcomes and only choose one when the measurement is made. When particles are entangled, you increase the number of possible outcomes. For each new particle that becomes entangled you increase the number of possible outcomes by a factor of two. Ten particles will have 2^10 = 1024 possible outcomes, and so on.
So to do math at the quantum level, you take a set of entangled particles and set up the measurement so that division with no remainder has probability one while division with any other remainder has probability zero. Then load your register with all the integers, let the probabilities interact, and take the measurement.
You have just performed division using all the integers at once.
If you can do this with a reasonably large register you can check all the factors of a composite number in linear time - the time it takes you to load sqrt(P) divisors into the register.
Easy peasy!
An interesting side-note is the idea of the universe keeping track of all possible outcomes until a measurement is made. If this works as predicted, the universe will have to keep track of 2^3000 possible outcomes, depending on the key length (3000 is the recommended RSA key length to be secure until 2030).
There are only ~10^80 = 2^240 atoms in the universe. If a quantum computer works as predicted, one wonders how and where the universe keeps track of all these states. At the very least, quantum computing is interesting because it will allow us to probe the limits of the universe in an entirely new domain.
Here's hoping we don't encounter a buffer overflow.
(Note: Some facts were harmed in the making of this explanation.)
There's no point in testing it now or trying to form an opinion at the risk of being wrong. D-Wave claims that really soon they'll have a quibit count (or whatever) high enough to break rather difficult encryption instantly as opposed to hours/months/centuries. If it spits out an answer, THEN it will be incontrovertible proof. Until then, it's not wise to say they're faking it or not faking it. I somehow doubt that they hired a mathematician to invent whatever algorithm it took the rest of the world a while to invent after the fact just to fake one possible result set.
Beware scam phone calls from Quantum PC support
My 30 year old Hewlett Packard 32S RPN Scientific is far more reliable than any $15M "Quantum Computer."
And mine is completely portable! HA!
NASA is well known for throwing away Butt Loads of $$$$ on "Gold-plated Toilet Seats" that don't work!
Bet the NASA Deputy Dir. has a gold-plated electric dildo.
Ha ha
Now a group from UC Berkeley and IBM's Watson Research Lab says it has a found a classical algorithm that explains the results just as well, or even better, than quantum annealing.
So we have two possibilities here:
1) D-Wave has built a device that at least theoretically can exist, which works more-or-less as advertised, or
2) D-Wave came up with a previously unknown solution to a class of computationally difficult problems, and would rather fleece a handful of investors than simply profit legitimately from their discovery.
Perhaps most importantly, the discovery of this new algorithm (which D-Wave's offerings predate) that "looks" like quantum performance on a specific task doesn't prove the D-Wave doing it one way or another. It just means we need a better test for quantum computing.
TFA's assertion of difficulty aside, I don't really get the problem with proving a quantum computer: "On a quantum computer, to factor an integer N, Shor's algorithm runs in polynomial time (the time taken is polynomial in log N, which is the size of the input).[1] Specifically it takes time O((log N)3), demonstrating that the integer factorization problem can be efficiently solved on a quantum computer and is thus in the complexity class BQP. This is substantially faster than the most efficient known classical factoring algorithm, the general number field sieve, which works in sub-exponential time â" about O(e1.9 (log N)1/3 (log log N)2/3)".
So this seems like a no-brainer - Does integer factorization scale in polynomial or subexponential time on a D-Wave?
That this thing is not a quantum computer in any meaningful way was clear from the beginning. But some people want to believe, no matter what. Sometimes that gets expensive...
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
Quantum computers are based on Deepak Chopra's Quantum theories. The computers are designed to by one with the Universe or something or another.
I don’t have time to dig past the summery. But I’ll toss a question out anyway and see if there is a short answer.
In QM all the information about a particle or group of particles is contained in their wave function. Sometimes the wave function predicts a single possible outcome measuring an observable in classical physics and sometimes it does not. When it does not, one can calculate a probability distribution describing the chances of a particular outcome of an experiment.
I am under the impression that at least some known algorithms for quantum computers produce an output where the qbits are in a state such that the desired output has a good chance be being the one observed when the qbits are measured, but the desired output is not the only possible one.
As such, it is expected that running the algorithm repeatedly on a correctly functioning quantum computer will produce incorrect answers at random but with a known probability of error. It seems like one could test if a system is really quantum by running one of these algorithms and seeing if the ratio of correct to incorrect output matched predictions.
Then again, I could be wrong in my understanding of what is supposed to happen with quantum computers.
The title is completely valid with regard to the strength of the computing model. The issue is that this "computing device" is basically useless for one more thing that was its core claim to being useful.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
How can you misunderstand the title?
Pure bullshite:
All gravitationally entangled systems work in specifics(classical behavior), as the wavefunction(s) have all collapsed into classical POINTER-VALUES. **You are HERE and going EXACTLY this fast.** Don'chano the moon(!) is still spooning whether you watch it or no.
Only low-mass or otherwise unentangled entities -- those systematically isolated -- exhibit superposition/quantum behavior. A quantum computer will do Jakk-shite except get its pimp laid by a babetek.
Remember analog computers? You would set up a circuit so that the voltage in one place was the answer to your computation, and then instead of calculating the answer you would *measure* the answer. We stopped thinking about them because it was tricky to set up the circuit for each calculation, but once you had it set up the computation would happen at the speed of electrons.
The D-Wave computer is similar to this. Given a polynomial in many variables (with positive real coefficients, and the variables only take the values 0 and 1), you might like to find the assignment to the variables that minimizes the polynomial. So D-Wave sets up a thermodynamic system whose steady state can be *measured* and gives an assignment to the variables that makes your polynomial small. Systems will naturally try to minimize their energy, and so the assignment is likely to be your perfect minimum (repeat 100 times, and the best assignment is likely to have appeared).
The question is whether the system minimizes its energy by classical thermodynamic flow (super fast), or by quantum effects (super-duper fast). It is, for that particular sort of problem, *much* faster than anything else ever. It had seemed to be so much faster and accurate that it had to be using quantum effects. But now somebody has found a faster way to do it classically, so that it isn't *that* much faster. For those of you in the know, the question isn't speed but the rate of growth of the speed: is the ratio of speed-up growing polynomially in the input, or exponentially?
Right here in this cardboard box. Don't ever open it, though, or you'll collapse its wave function and may cause it to disappear instantly.
D-Wave has Josephson junction qubits on their chip and couple them. Yet, somehow they are supposed to end up with a machine that is a classical annealer? Although the behavior of the box is exactly what you'd expect from a quantum annealer?
Seems rather far fetched.
I wished before anybody was writing about D-Wave they'd watch this video form the last Q+ hang-out where the Troyer et. al. research into the characteristics of the D-Wave machine was presented.
Hello World, is my Official Website: http://picardes.com/
http://www.youtube.com/watch?v=Q1YqgPAtzho
that^ seems to help my mind grasp it..
essentially the quantum computer would have to represent solutions of all possible outcomes of a 'problem' and nothing is chosen until witnessed .. or something
Scott Adams saw it coming nearly 2 years ago dilbert.com/fast/2012-04-17/
Except for all of scientific knowledge, of course.
It's pretty clear that you, just like most of the other posters, don't understand what D-Wave's machine does or how it's being tested.
The D-Wave computer is supposed to perform quantum annealing. Annealing, quantum or otherwise, is essentially an optimization problem (you're looking for the global minimum). Both the quantum and the classical annealing operations will find local (but not global) minima some of the time, but the pattern of these non-optimal solutions is different between the two. So you take the output from the D-Wave and try to match it to simulations of quantum and classical annealing. According to the article, the D-Wave output more closely matched what you'd expect from simulated quantum annealing but these researchers have now come up with a simulation of classical annealing that more closely matches.
Surely they would have bought it for what it can do, not how it does it, does jt do what they want or not?
There's nothing quantum about it whatsoever. The entire thing is a complete fraud.
A TI-99 could sale for so much money...
Why does quantum computing matter?
Because entangled particles change state instantly. Instantly means faster than light. Zero wait state. Zero. This makes a quantum entangled bit more powerful than al the rest of the computers on earth. The vistas of big data become almost godlike. Imagine that any encryption that relies on formula can be instantly cracked, this is just the tip of the iceberg. Once quantum computers are active, its a whole new ballgame.
The rest of knew this years ago. Too bad for Google none of their employees understood this.
An interesting side-note is the idea of the universe keeping track of all possible outcomes until a measurement is made. If this works as predicted, the universe will have to keep track of 2^3000 possible outcomes
The theory says that a quantum computer can simply offload this monumental task to a vague entity that you call "the universe." Doesn't this strike you as a little too good to be true? The ultimate "free lunch," or a violation of conservation of-something-or-other?
TFA makes me feel justified in my skepticism.
Another question... if quantum computing is real, can it be used to speed up Bitcoin mining by a few orders of magnitude?
That that is is that that that that is not is not.
The fine article claims:
Most physicists fully expect a useful quantum computer to eventually emerge, [...]
I am a physicist and I don't think a useful quantum computer will ever emerge. The problem is very simple. In order for a quantum system to calculate exponentially faster than a classical system, it must contain exponentially more useful information which makes it exponentially more sensitive to noise. An early computer researcher (perhaps Jon von Neumann) used a similar argument to conclude that digital computers would eventually supersede analog computers because the precision of analog computers is limited by the noise floor which is very hard to beat back while you can make digital systems arbitrarily more precise by simply adding more circuits (or more time).
In simple terms, for every extra decimal digit you want to add to the size of a number you can factor with a quantum computer you need to reduce the effect of noise by roughly a factor of 10. I don't think this is greatly different from the limitation of classical computers where for every decimal digit you want to add to the size of numbers you want to factor you must multiply the time/size of computation by roughly a factor of 10.
Despite this reservation, I think we should continue funding research in quantum computing.
We don't see the world as it is, we see it as we are.
-- Anais Nin
When for-profit corporations perform research, they usually do so with integrity, i.e., their goal is to genuinely advance the state-of-the-art of whatever field is being researched. Only in a small minority of cases is their goal to perpetrate a scam. Just sayin.
That that is is that that that that is not is not.
Colin Williams of D-wave spoke at Fermilab. His presentation was recorded http://vmsstreamer1.fnal.gov/L....
The possibilities of quantum computers today are as overstated as were the possibilities of Analog Computers in the 1960's, and I am taking bets that we won't see quantum computers outperform conventional computers on useful tasks within the next 30 years.
Quantum mechanics are a model of reality. They are a useful model, but to think that you can setup reality such that by measuring physical observables you can yield a large, accurate result that is full of information repeats the same fundamental misunderstanding that led to exxagerated expectations when Analog Computers were introduced. Theoretically, an Analog Computer (just like a quantum computer) has "infinite computing" power, even if it is a simple circular slide rule, because in theory, you can setup input values with infinite precision and yield a result with infinite precision, representing an arbitrarily complex computation. In reality, however, you cannot setup the inputs with arbitrary precision, you won't be able to measure the result with arbitrary precision, and the physical model behind a circular slide rule (the Newton mechanics) leaves some aspects of reality unmodeled, so e.g. the effects of gravity bending the space your slide rule resides in will already render the result precision finite.
Physical models are not laws that reality somehow magically abides to. Quantum mechanics are not different from Newton's mechanics in that they do not model every aspect of reality, so even if there wasn't the problem of setting up inputs and measuring outputs with arbitrary precision, results would still be tainted by effects (gravity, "dark engery", "dark matter", ...) that the model does not include.
And there is no compelling reason to believe that just because humans currently favor statistical distribution functions for modelling certain aspects of reality, this reality would "evaluate zillions of possibilities results in an instant and conveniently return the one that adheres to the model". "Coherent entangled quantum states" will turn out to take more and more time to be setup and finally become "decoherent" while being measured as the amount of information that is to be procecessed increases.
The one thing that quantum computers will be good at (and maybe better than conventional computers) will be the simulation of quantum systems similar to what they are. But if you need a real banana to simulate what a real banana would do, you are not building a next generation computer - you are just setting up an experiment.
they could pay the tax they're currently avoiding
We need to realize that at the fundamental level we know nothing about microscopic ("quantum") world. Any statements of solving NP-complete problems is linear time or any attempts to explain how quantum mechanics works is just a hoax. It just happened to find a mathematical description of the microscopic world which works. It doesn't mean at all that "probability waves" of any kind exist. It just a mathematical model to produce hermitian forms and real observed values.
Its both a quantum machine AND not a quantum machine.
There is no such thing as a quantum computer because there's no such thing as quantum entanglement. It's a 90-year lie. There is no example of a so-called quantum effect that can't be explained classically.
the article is mis-reported... or at the very least confusing. if you read the article carefully it describes failures of some of the researchers, followed by reporting the successful analysis and conclusions, possibly by a completely different team. the time-lines are not made clear, either. this sounds like a reporter decided to mis-represent the facts.
http://en.wikipedia.org/wiki/Energy_Catalyzer
AC CAPTCHA = "collapse"
Yeah, I've never been clear on exactly what stuff D-Wave does fast, or how it does it, in spite of having been to a few of their presentations, and D-Wave has always been clear upfront that their machine works differently from Shor's proposed quantum computers that sparked all the "It'll let you break crypto" interest.
But they apparently at least run some kinds of demos faster than you'd expect them to be able to do with conventional computers, and do it in ways that are interesting enough for a few big players to invest the money in more research which might lead to discovering ways to apply it to their real-world problems and not just lab demos.
Nobody doing "traditional" quantum computing has built anything that can solve problems bigger than factoring 15 = 3x5, or maybe somebody's gotten up to 21 by now. But it's still not close enough to sell anything to anybody; it's still just pure research.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
If I understand correctly, you are actually only certain of position or momentum when the wave function collapses to point values. i.e. You are HERE or you are going EXACTLY this fast.
When you perform a measurement (say of position), the wave function will indeed say: The probability of finding the particle at 'x' is 1. However, the more certain you are of it's position, the less certain you are of it's momentum because of the relation dPdM ~ h_. (Where d is the uncertainty in the measurement; h_ is Planck's Constant). You are correct in that it's the wave function that is spread out, not the particle itself. If you measure the particle's position again a little later, there's no guarantee you'll find it again at 'x'.
P.S. I've not studied physics formally, but I've found this series from Yale to be quite instructive and easy to follow. I might have misunderstood, so I welcome any corrections from actual physicists.
Plan My Week for iPhone
It's not too good to be true, and the confusion only comes from the original post saying misleading things like "The universe keeps track of" and "The universe appears to calculate". The universe is not some entity or object keeping track or calculating at all, and all of these sort of probabilities happen all the time anyway, it is just we haven't constrained the outcomes into a way which gives us computational power. After all, position is a continuous operator, so whenever we look at an electron "the universe keeps track of an infinite number of probabilities", to use the bad phrasing of Okian.
It's pretty clear you are not a scientist. I, on the other hand, make my living with science. Models are not evidence of reality. Data provides evidence FOR a model. And as some wise person said, all models are wrong to varying degrees and some are useful. But certainly , models fitting data, especially disparate models fitting are evidence that we do not understand the reality of the situation.
Entia non sunt multiplicanda praeter necessitatem.
Hear, hear! Mod parent up!
There is no substitute for common sense. Especially, no body of rules will do.
Are "D-Waves" related to "D-Particles?
Dr. Who said he was "fond of" D-Particles in "The Time Warrior" as the 3rd Doctor in Season 11. The first episode where Sara Jane showed up.
So next thing you know, Google will have Sontarans appearing shortly.
Tracy Johnson
Old fashioned text games hosted below:
http://empire.openmpe.com/
BT
If "quantum" computer is possible then someone needs to start new project "Universal Schrodinger Solder" to turn human body into new "quantum" state -- dead and alive at the same time. I can see mind blowing possibilities there...
Basic idea of flux qubits:
PHYSICAL REVIEW B VOLUME 60, NUMBER 22 Superconducting persistent-current qubit
They have a section on decoherence. For detail look in the PHD thesis of casper van der wal.
Some theoretical more general (still Jospehson-based devices) background:
REVIEWS OF MODERN PHYSICS, VOLUME 73, APRIL 2001
Quantum-state engineering with Josephson-junction devices
And (even more general) on two level Systems:
Caldeira and Legget, Physical Review Letters January 26 1981
Everthing (and more) you need to know about "The dissipative two state system": Legget et. al: Reviews of modern physics 59, January 1987
The moment when dwae realized they dont have a quantum computer:
Thermally assisted adiabatic quantum computation
M. H. S. Amin,1, â-- Peter J. Love,1, 2, 3 and C. J. S. Truncik1
(condmat 0609322)
Practicing research scientist, at a real university, actually. You make your living with science hey? That could mean anything. From your tone I formulated a few hypotheses.
When two models (some people call these "theories" or "hypotheses") fit the data, but one fits better, we call that evidence in favour of that model (which you agree with). The simplest model that fits the data well (i.e. the simplest model that fits the most data) is considered the best description of reality. It's probably wrong, at least in some details, but it's the best at the moment. That's as close as anyone can get to "describing reality."
Did you do the experiment in high school where you measure a ball rolling down an inclined plane and plot the position over time? Then you fit a curve to the points and come up with d = vit+1/2at^2? That experiment is evidence that objects undergoing accelerated motion move in a way prescribed by that equation. Yes, it's not fully correct in this particular case (which you can detect in high school if you do it carefully enough). The angular velocity of the rolling ball soaks up enough energy to be noticeable. Also friction, of course.
What these people (other practicing research scientists at real universities, by the way) have done is similar. They figured out what pattern of mistakes would be expected from classical thermal annealing and quantum annealing (using models called thermodynamics and quantum mechanics), and compared these predictions to what the machine actually outputs. One fits better, providing evidence that the machine is more likely using that process.
The problem of quantum physics is that it says as soon as you measure something you destroy it or change it, so by the very definition of quantum physics, the d-wave computer cannot directly be tested, that is, unless you can predict what the test would be, and the outcome, that being different from classical physics. Any quantum physicist around that can tell us if that is true?