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Molecular Photography
med dev writes "An article at New Scientist discusses the latest in quantum computing - 1000 bits stored in the electron spins of a single polymer molecule. Add in a recent release of the how-to for the complete quantum computer, qubits that work, and it may not be much longer before Google is running on a server the size of a sugar cube."
nuclear magnetic resonance (NMR) instrument.
I've done NMR, it takes ages. Preparing the sample takes about 30 minutes. Running the NMR takes between 1 and 20 minutes depending on what you're measuring. Analysing the results depends on how good you are.
I can't see google using this any time soon.
Moreover, the peculiarities that make quantum computing interesting (e.g. the ability to factorize in polynomial time) also make it completely inappropriate for mundane tasks. So please stop the "google in a cube" shit.
The Raven
Blockquoth the article:
They did record at least 1024 bits. But I guess they aren't being used, because otherwise,
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I have to wonder what type of redundancy and error correction will have to be built into quantum computing.
Lots and lots. In 1995 Peter Shor (the factoring guy) and Robert Calderbank devised that possiblethe first error correcting code for quantum computers. Many others have been designed, including proposals for some that operate as a natural consequence of the system being used. Here is a good survey of the field.
It has been shown that if the error rate is below a certain threshold (currently estimated to be one error per 103 operations for optimists, and one per 106 per pessimists) then efficient error corrected quantum computation is possible. The pessimistic estimate is well above what is currently possible experimentally in quantum systems but the problem seems to be an engineering one, not a fundamental one. It should eventually be possible with clever implementations of qubits, shielding and cooling to near absolute zero.
:wq
Synchrotrons are used for x ray crystalography. they can produce X-ray photons at a wide range of frequencies and you can carefully select the photons you want using an x-ray monochromator.
The X-rays will not tell you anything about the nuclei of the molecules you are looking at, as the photons go through the electrons in the crystalised protein they will make an interference pattern, and from that you can calculate the shape of the electron cloud around the molecule.
Note that this gives you no infomation on the quantum state of the nuclei, which is what this quantum computer needs to know.
Nuclear Magnetic Resonance molecular analyisis works in a similar way to Magnetic Resonance Imaging, just on a smaller scale.
for more information click here
You are incorrect. Classical computers can search an indexed database in log(n) time. Grover's algorithm allows quantum searches to be much faster, perhaps even in constant time. Search engines could benefit immensely from quantum computing.
Lots of information can be found on Lov Grover's quantum search algorithm. Do a search for it on Google. Dr. Dobb's even analyzed the quantum source code for the algorithm. Pretty cool stuff.
Such variances are common and expected in quantum computing; hence the field of Quantum Error Correction. (Google for more...)
Does anyone know if Synchrotrons, like the one in Saskatoon, SK, Canada play a part in researching molecular computers?
No, not at all.
The article mentions a magnetic imaging device.
Is that like a synchrotron?
No, not at all.
Syncrotrons produce gamma/X-rays. Expose a polymer to some of those, and it won't stay a polymer for long..
NMR instruments (and MRI devices) use radio waves. Much longer wavelength, much lower energy.
The only similarity I can think of is that both use big magnetic fields, but for different reasons.
(syncrotrons use them to accelerate particles, NMR machines use them to split the spin energy levels)
Let me explain more clearly, because it seems that some of the moderators didn't understand my comment.
Think about a photon, which has a linear polarization: up-down, left-right, slantwise, or at whatever angle you want. You can in principle put in an arbitrary amount of information in setting the polarization angle of a photon. You could divide a circle into as many parts as you want, and set the polarization to an angle corresponding to the value you want to send. This is like how they pack 1024 bits into a 19 nuclei molecule.
Now, the problem is reading the data back out. If you have only one photon in a particular polarization state, you can't determine that state with any accuracy. You can in fact only get one bit of data out of that photon. You can pass it through a polarizer and either it makes it, or it does not. This gives you information about the polarization state but it destroys that state in the process. You can put lots of information into a single photon, but you can't read it back out.
Now let's imagine that we have lots of photons, in a laser beam for example. We can set them all to the same polarization state. Now we can read the polarization quite exactly, by using large numbers of photons and turning our polarizing detector until we get a peak in the output.
Even though all the photons are in the same state (like in the NMR molecule experiment), it is because there are large numbers of them that we can read the state back out accurately. We would NOT be able to read back the data from a single photon, and in the same way we would NOT be able to read back the data from a single molecule.
Hopefully that explains my comment above. A qubit, whether photon polarization or nuclear spin, holds only a limited amount of information, and you can't read more out than it holds. There's no way you can get 1024 bits into 19 nuclei, and no one should try to "spin" the results of this experiment that way.