Several Quantum Calculations Combined At NIST

Al writes "Researchers at the National Institute of Standards and Technology (NIST) have demonstrated a crucial step toward building a practical quantum computer: multiple computing operations on quantum bits. The NIST team performed five quantum logic operations and 10 transport operations (meaning they moved the qubit from one part of the system to another) in series, while reliably maintaining the states of their ions — a tricky task because the ions can easily be knocked out of their prepared state. The researchers used beryllium ions stored within so-called ion traps and added magnesium ions to keep the beryllium ones cool and prevent them from losing their quantum state." In related news, another reader links to an Australian study indicating that quantum computers "can continue to work perfectly even if half their components, or qubits, are missing."

This may be slightly off-topic, but

[Anonymous Coward]

Seriously WTF is Quantum Computing? I've looked at the wiki articles and googled things, and I'm still lost. I did read that unless you have an education in this area you just won't get it, but help me out here.

Re:This may be slightly off-topic, but

[xerent_sweden]

So basically it's quantum physics applied on computer science. Computers of today are based on semiconductors and diodes, which allows us to build electric circuits with memory. In this case, it's voltage applied or voltage off - one or zero. Quantum computing is a whole new world of computing; because it's based on the principles of quantum physics. This means that a quantum computer does not resemble the computers of today at all. In a quantum computer, information is stored in "qubits", which is 0, 1 or "undetermined / both". This is a direct application of the wave/particle duality of matter (wiki: De Broglie-wavelength). Working out how a quantum computer - which behaves totally differently from anything we have today - and constructing such a device is really hard. Theoretically, such devices would be more efficient than our computers - and that's an understatement. This story means that we've taken yet another small step towards practical quantum computers, but also that it'll be reposted at least 100 times before working quantum computers are reality. (Off the top of my head, please correct me if I wrote something in error. Thanks! :)

Re:This may be slightly off-topic, but

[iris-n]

You just couldn't resist using Everett's interpretation, could you?

I don't think it is a good idea using it to explain something to laymen. They usually end up thinking that quantum mechanics is some kind of inaccessible black magic.

Just to be clear here, it is possible (and it is what's done most of the times) to describe quantum mechanics without ever talking about splitting universes.

Let's see: the qubit can hold some combination of 0 and 1 (NOT 0 and 1). By the same reason (superposition), the quantum computer can perform multiples paths of computation at the same time, which can be used to accelerate the computation of some algorithms.

Quantum computers are quite sensible to noise; it causes decoherence, which can be understood as a loss of quantumness. In other words, a qubit that suffered too much decoherence can't hold a superposition of 0 and 1 anymore.

See? It wasn't that difficult.

Re:This may be slightly off-topic, but

[ajs]

Quantum computing is a whole new world of computing; because it's based on the principles of quantum physics. This means that a quantum computer does not resemble the computers of today at all. In a quantum computer, information is stored in "qubits", which is 0, 1 or "undetermined / both".

Yeah, I'm still not buying it. Quantum computing has yet to do anything that lives up to even its basic promise. If it's possible to harness these states, we should have been able to demonstrate, at the very least, the capacity for computation on the scale of, say, the average pocket calculator. And yet, we've still gotten nowhere. Why? Well, there are many possible reasons, but I tend to favor the simplest: quantum mechanics is a field that is built on some very nice math and as many intersections with reality as we've been able to test, but fundamentally we don't really understand what's going on at the level of the atom, much less at the level of its constituent parts. As we gain that understanding, our math is likely to be revised and refined several times.

Put simply: we're like Aristarchus of Samos measuring the relative sizes and distances of the sun and moon. He was more accurate than any before him, and his understanding drove countless others' discoveries, but if he'd tried to put a man on the moon using that math, he would have failed.

We're doing roughly that: trying to put a man on the moon at quantum scale, and while the discoveries of Plank and Dirac and all of their successors to the current day have enlightened us as to the nature of the quantum world, we're still not so much farther along than Aristarchus. I expect there to be at least one more wave of truly physics-shattering discoveries on par with the uncertainty principle before we even start to be able to perform real computation at the quantum scale. Even then, it's entirely possible that those discoveries will invalidate the entire idea of using superposition for computation.

Then again, I could be completely wrong, and quantum computing could be workable tomorrow. Just don't go betting the farm on it.