Fredkin Gate Breakthrough Brings Quantum Computing Within Closer Reach (pcworld.com)

An anonymous reader quotes a report from PCWorld: Quantum computers are based on atomic-scale quantum bits, or qubits, that can represent both 0 and 1 simultaneously. Realizing that potential, however, depends on the ability to build working quantum circuits. The quantum version of the classic Fredkin gate exchanges two qubits depending on the value of the third. It could be a key component of quantum circuitry, but because of the complexity involved, no one has ever managed to build one in the real world -- until now. Whereas the Fredkin gate typically requires a circuit of five logic operations, researchers from Griffith University and the University of Queensland used the quantum entanglement of particles of light to implement the controlled-SWAP operation directly. Essentially, the scientists demonstrated how to build large quantum circuits directly, without having to use numerous small logic gates. That, in turn, puts real quantum computers within closer reach.

Comments

Spooky confusion at a distance.

[Tablizer]

I give up, quantum stuff makes sorcery sound logical in comparison.

Too bad Einstein's not still around; maybe he could find a more down-to-earth or simpler explanation. He seemed to be the only prominent one questioning that something seems really out of whack, as if we are missing a yuuuuuge piece of the puzzle.

He solved the ether weirditity by plugging in relativity. Similarly, maybe the probability and multi/ghostiverses games will fade away when the equivalent of relativity is applied to quantum stuff.

Maybe particles are like sperm in that when one photon is apparently emitted, there's really many particles emitted, and the first one to hit (react) shuts off the other particles so that they are invisible, almost like neutrinos, so that we don't detect them.

Thus, the interference pattern really *is* a wave; it only looks like a lone particle upon detection because the others cloak. Well, I'm rambling, but you get the idea: there's a BIG IDEA out there to be discovered...

Re: Spooky confusion at a distance.

[Anonymous Coward]

The problem is that QM is straight forward if you have high school calculus plus some math, mostly notation, that would fit within a small appendix. Things like the particle wave duality aren't that mysterious or a problem at all if you can work out actual QM instead of trying to contemplate a bad analogy. A large amount of the mysticism and confusion is not there in what is a sophomore level class. Most of the problems people think make QM confusing comes from trying to make math-free analogies connecting to everyday experiences. This isn't unique to quantum, as you can make classical physics riddles that even physicists will get wrong using intuition, but can be worked out straightforwardly using a formal approach. This is not to say that there is a lack of questions still left even at the formal level, and there is always room for more simpler explanations. But like many things in life, you can't expect everything to be reducible to a level you can just skim through in a couple of minutes, and understanding some things in this world takes more dedication than half-assing. If you have some math background, even rusty, you can get through a couple chapters of an actual textbook instead of reading numerous popsci books.

Re: Spooky confusion at a distance.

[Tablizer]

But that's possibly like saying, "epicycles are straight forward to model if you remember your math". (Circular regression?) While possibly true, epicycles were the "wrong model" to begin with for orbital mechanics.

One can model just about any fake or spooky thing that follows patterns with math/algorithms, but that doesn't mean the model reflects the underlying mechanism well.

If it's anything like fusion...

[Sax Russell 5449D29A]

Quantum computing will always be 20 years away. Getting anything practical work done on quantum computers is not likely going to happen in our lifetimes (unless you redefine 'practical work', of course).

Re:If it's anything like fusion...

[MouseR]

Quantum computing will never be observed. Every time we look at it, the expectation changes.

Re:Quantum computing in layman's terms

[JoshuaZ]

Quantum computing can be described as a method, a technique, which allows for the computer for a given task to take a peak into the future and to read the answer from the future back to the present.

This is completely wrong. There are in fact computational models that have been worked out about what a computer that could peak into the future would be like and they are insanely more powerful than quantum computers. See http://www.scottaaronson.com/papers/ctc.pdf. Quantum computing has nothing remotely like what you've said. I suggest for an actual primer on the topic reading Scott Aaronson's excellent book "Quantum Computing Since Democritus" which doesn't require anything beyond a little basic linear algebra. And in the meantime, if you don't know much about a topic, maybe don't make extreme policy suggestions?

Re:Quantum computing in layman's terms

[alvinrod]

Alternatively, this video does a reasonable job at outlining how a quantum computer works. It doesn't go into too much detail, but it's probably enough to give the average person an idea of the differences between quantum and classical computers.

Is quantum computing within reach?

[PopeRatzo]

Well, it is and it's not.

Re:Real Quantum computing in layman's terms

[JoshuaZ]

Pretty much everything you've said is wrong. Yes, the Delft experiment used filtering. No, the filtering doesn't do what you think it does. But more to the point, there have been many experiments prior to the Delft experiment that didn't use that sort of filtering and still got results consistent with entanglement. See e.g. http://www.nature.com/nature/journal/v409/n6822/abs/409791a0.html for an example.