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Significant Advance in Quantum Computing
wcitech writes "Apparently scientists have been able to create circuitry that mimics the behavior of atom pairs by using superconductors." From the article: "The work, reported in the Feb. 25 issue of the journal Science, demonstrates that it is possible to measure the quantum properties of two interconnected artificial atoms at virtually the same time. Until now, superconducting qubits--quantum counterparts of the 1s and 0s used in today's computers--have been measured one at a time to avoid unwanted effects on neighboring qubits." The second Quantum computing revelation this month, in fact.
Before I go worrying about quantum computers, I need to get my own working. But in a quantum world, I guess they are working AND messed up at the same time.
'Every story, if continued long enough, ends in death.' --Ernest Hemingway
This question may be stupid but...
Would we need to read 32 quantum states at a time to get '32-bit' registers to build basic processors??
Slashdot: Where people pretend to be twice as smart as they really are by behaving like children.
No fair! You changed the outcome by measuring it!
-- Thou hast strayed far from the path of the Avatar.
the whole paradigm of 'xx-bit processor' will go out the window once the technology matures and software makes full use of the capabilities.
"So, computers. I hear they basically break down to a bunch of ones and zeroes. I don't know how that means I can see naked women on my screen, but God bless you people"
vodka, straight up, thank you!
Lawrence Person (lawrencepersonh@gmailh.com (remove all "h"s to mail)
http://www.lawrenceperson.com/
Well, obviously it isn't ready but there are steps between "hey, I've got a good idea" and "you want to buy this product from me???"
Quantum computing: a view from the enemy camp
Quantum computing relies on processing information within a quantum system with many continuous degrees of freedom. The practical implementation of this idea requires complete control over all of the 2^n independent amplitudes of a many-particle wavefunction, where n>1000. The principles of quantum computing are discussed from the practical point of view with the conclusion that no working device will be built in the forseeable fu
If your idea of quantum computing is a computer only capable of a handful of bits and costing millions, then yes... the technology is ready. Would you like fries with that?
Want to improve your Karma? Instead of "Post Anonymously", try the "Post Humously" option.
From http://en.wikipedia.org/wiki/Quantum_computer#Bits _vs_qubits
"This dramatic advantage of quantum computers is currently known to exist for only those three problems: factoring, discrete log, and quantum physics simulations."
I don't see Quake 10 on the list, so what's the point?
Of course! We created God...in our image and likeness, no less.
"Once we've identified and embraced our sickness, we'll have strength...and that's when we get dangerous." - John Waters
This is very interesting. Where does /.'ers get their ideas from? http://hilbert.math.uni-mannheim.de/~seiler/cray.j pg/
Nothing.
No, wait. It means that we're going to have to stop lying to ourselves, admit that no communication mechanism can ever be capital-S secure, and listen to the geeks who've been saying that security needs to be convincing people not to try, detecting when they do, and being able to recover from any intrusion.
Instead, Tien Kieu from my university wants to solve arbitrary Diophantine equations using quantum effects. If he's a) correct, and b) it becomes possible to create the required quantum behaviours for arbitrary equation, the following problems become solvable:
Needless to say, to say people are sceptical of Kieu's ideas is an understatement, but it's fun to speculate about the "what if"...
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
who said "rectun" for rectangle, and "enitrate" for integrate, etc.
He tried to say:
"To integrate, you use small rectangles instead of large rectangles in your Riemann sum because they work better."
but ended up sounding like:
"To penetrate, you use small rectums instead of big rectums when your wiener's up because they work better."
True story
You've got it in one. According to Kieu, his system is a non-computable process; you can't simulate what it does on a Turing machine. Hence your objection doesn't apply to his claims.
However, there are apparently lots of other objections.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
A quantum register does not actually represent all possible inputs. It represents a superposition of all possible inputs; this is a very important distinction.
When the register is 'read' after a computation, it contains exactly one result representing the results of one random possible input. Using a classical algorithm with the register would be exactly like a normal computer with a random setting as the input.
Getting anything special from a calculation from a qubit register is extremely tricky. Shor's algorithm does a special quantum fourier transform on the register to get the most common possible output [this is a metaphor] and only works because the values of the qbits are not independent (and thus do not represent all possibilites). The algorithm must be run several times to even get a statistically meaningful result.
Remember, the average Slashdot reader doesn't have a degree in physics or electrical engineering. They are typically dropouts from junior college CS programs. If they are lucky enough, they drift into a job administering Windows machines at a non-profit organization. Chatting about "quantum computing" lifts their spirits, however briefly, and distracts them from their humdrum lives.
The similarity between brains and a quantum computer comes from the fact that the neurons in the brain also process the data in parallel. There is no quantum computing going on inside the brain. There recently was an article about an autistic savant explaining his calculation skills. Numbers are just shapes to him, and multiplying them means he just merges them in his head and reads back the emerged shape. Probably his visual cortex is doing the parallel operations on the shapes here (maybe similar to using the shader engines on your graphics card for doing calculations).
Thode PDFs don't speak about quantum computers. They speak about using quantum devices to build more efficient classical computers (the fact that they call it quantum cellular automata doesn't mean that it is a quantum computer, it just uses quantum dots for operation). Indeed, they depend on inelastic processes, exactly those processes which actually pose the biggest problem in quantum computing.
Not every computing which uses quantum mechanics is quantum computing (indeed, otherwise our current computers would have to be quantum computers since semiconductor physics just cannot be done classically).
Quantum computers are computers which specifically work with quantum information (i.e. superpositions and entanglement). The papers you cited use quamtum dots to more efficiently process classical information.
Now that doesn't mean that the QCA work is less important (indeed, I think it's far more probable that you'll at some time work with computers based on QCAs than that you'll ever see a real quantum computer in your life). It's just that QCAs are not QCs.
And yes, I am a quantum physicist (although I don't work on quantum computing).
The Tao of math: The numbers you can count are not the real numbers.
There's no need to speculate on how a quantum computer will work. We already have working examples, and we already know the generic properties of them. Instead of trying to figure it out on your own, go read the vast amounts of information on the topic available.
The three properties of the QC that are most important:
1. You can set the state of the qubits to whatever you like.
2. You have some transformation that the qubits will go through. This can be arbitrarily complex, and will be the most interesting part of the machine.
2. You can get a really good estimate of the state by doing the operation from the same initial state several times. See, when you go to measure a quantum state, you get one possibility of many. You have to make a lot of measurements to figure out what is really happening.
The best comparison is to think of the single-slit experiments you did in High School physics. You take a parallel light source (sunlight, laser, light from a distance) and have it strike a plate with a very thin slit. Then you hold a piece of paper where the light comes out. You will see bands of light, and some chromatic aberrations (you will see colors).
If you consider a single photon travelling from the light source and approaching the slit, passing "through" the slit, and then travelling off into any one of the finite number of directions, you ask the question: How can we predict which way it will go?
The answer is you can't. You have to do it a lot (like with a beam of light) and you can easily see what the probabilities are from that.
You can probably think of the experiment I described above as a very simple form of a quantum computer. You set the input - the light travelling into the slit. You have the transformation - the slit. And you can read the results by doing it several times.
That's all quantum computing will do for you. It's up to the really smart guys in white lab coats to figure out how to turn that into something useful.
I believe this will all be abstracted away from your eyes, just like today you don't worry about which register your integers is stored in and such. You will merely say, "Run the calculations on this set of data and give me the result" and it will do it before you can blink.
Heck, ordinary people won't even get to own a quantum computer until two things happen: (1) We find a better use for them than hacking into banks and stealing people's identities, and (2) we have built up enough of a reportoire of transformations that some subset of that is actually useful to solve the problems we face in computing today.
The radical sect of Islam would either see you dead or "reverted" to Islam.
Also,
Time is relative to the observer, and quantum theory treats time linear but Einstein says otherwise. Take a look at an EPR situation in space-time (talk by Roger Penrose).If we can read the state of two entangled atoms, is communication at greater-than-light speed now possible? Wouldn't this violate causality?
Just curious.
--Ryv
NP stands for Nondeterministic Polynomial Time so, yes, in theory, a quantum computer should be able to solve any NP problem in polynomial time, since any NP Complete problem (Im not sure if factoring ala Shor's algorithh is one) will reduce to any other NP problem in P time. As far as P = NP, a quantum computer would not resolce that, since it is still just a brute force attack on an NP problem. Resolving P v. NP is a theory problem, not a hardware problem. It might be more acuarate to call it a "non-deterministic" computer. You can currently similate a quantum computer (VERY slowly) on a serial device, and it could, eventualy, solve any NP problem. You actualy wouldn't need the simulation of the QC, but either way "eventualy," in most nontrivial cases, would mean after the sun burns out...
There have been no algorithms devised for quantum computers so far that can solve NP-Complete problems like the Travelling Salesman Problem in polynomial time.
It *is* possible to achieve a square-root speed-up on essentially any problem in NP using Grover's algorithm, but it has also been shown that this is the best that can be achieved without exploiting the structure of these problems in some way as yet unknown.
It would be a major advance if anyone did come up with such an algorithm, and in fact (I think) most people believe it's not possible. Incidentally, resolving this question either way would not imply that P = NP or P != NP.
there is no quantum algorithm to speed up np complete problems. this whole post is just not right