Australian boffins say Quantum Pentiums are on the horizon Australian boffins have overcome one of quantum computing's big problems by building a gate comprised of two qubits in silicon, using techniques very similar to those used to manufacture whatever device you're using to read this story. Building a quantum logic gate in silicon is a big deal because hitherto it's only been …
Really, El Reg.
In a conventional computer, the presence or absence of an electron indicates a one or a zero. Quantum computers store information in the spin of an electron which, thanks to the weirdness of the world at quantum scale, can be in several states at once. A single electron in a quantum computer can therefore be a zero and a one at the same time, which creates the potential for parallel processing inside a chip and therefore for faster computation.
Reformulate:
In a classical computer, bit states can be encoded by the presence or absence of electric charge. In quantum computers, qubit states can be encoded by the spin state of single electrons which, quantum mechanics tells us, can be in a superposition of states 0 and 1 akin to the superposition of an à priori unknown classical bit in classical probability, albeit here one must use complex numbers to express the "quantum probability". Interesting for computation are arrays of N entangled qubits, which express a complex probability distribution in a 2^N large space, but then one still has to manipulate this qubit vector using quantum gates to yield the computation of interest, a feat that is still a bit in the future.
"In a conventional computer, the presence or absence of an electron indicates a one or a zero."
Thats the presence or absence of a large number of electrons gathered at a single storage location, (where they are sensed due to their effects on the electrical characteristics of that location).
@ Destroy All Monsters - thank you. However, I'm in need of the Ladybird Big Book on Quantum Computing for kiddywinks, because even though I understand the notion of quantum superposition in general, I completely fail to understand how on earth we can make use of it to compute anything. If you can point me to something that describes how starting at ignoramus level,'twould be much appreciated. But if there isn;t anything of the sort, I'll be the one just standing in the corner oohing and ahhing at the red, no green, no red with a greeny tinge? blinkenlights... :-}
However, I'm in need of the Ladybird Big Book on Quantum Computing for kiddywinks
Let's just call it a quantum leap forward in computing :).
I can't get my head around this either, because it gets weirder the closer you look at this. As it is possible to have two whatsits act in sync, would that mean that every computer leaving the factory can be spied upon forever? And how does that sync work, because observation changes state so looking at Schrödingers cat would make your local cloned cat acquire the same state.
I suspect that many in that branch of science must be raving alcoholics...
(joking aside, I will indeed have to look for a beginners book on this..)
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If you can point me to something that describes how starting at ignoramus level,'twould be much appreciated.
With pleasure. I have found that the easiest way to start (though it does need some perserverance) is Scott Aaronson's "Quantum Computing Since Democritus" (and in a lesser way the lecture notes). This may not be what you are looking for because he's only indirectly talking about the algorithms.
"The computation" is actually applied linear algebra, continuous or discrete, in a complex vector space (although this may not be best representation or even an adequate one, work is still needed), where at the end you have to probabilistically select a single element of the vector you are massaging. I confusingly feel that this means nature works as a constraint solver, not as a clockwork universe with probability bolted on, but that's just my view, sure ain't good enough to make this precise.
This may not be what you are looking for because he's only indirectly talking about the algorithms.
For those who want a follow-up that describes the actual algorithms, there are a number of good introductions online, such as this one for Grover's Algorithm. Note, though, that even simplified explanations are going to require some level of comfort with complex numbers, linear algebra, etc.
(Many years ago I ran across an explanation of Grover's Algorithm that gave a decent sense of how it worked without really describing the mathematics at all, but a quick search didn't find it. And without the math it may mislead readers anyway.)
built "using techniques very similar to those used to manufacture whatever device you're using to read this story"
good grief, I certainly hope not, I'm reading this on an Apple device and if the NSW guys have been treating their construction bods the same way Foxconn do, 1/10th of them have certainly killed themselves by now..
Also I'd like to add that if you record all the electrons as being zero at the same time, your quantum computer might be switched off.
Two or three times a year someone announces that they've identified another physical system capable of computing with qubits. Unfortunately, that alone is a lot like identifying a new fluid that one can blow soap bubbles from. That is not the really really difficult part.
Now imagine blowing a soap bubble as large as the continent of Europe, and keeping it from popping for a month despite all the gusts of wind and rain and lightning here and there. THAT is the hard part, and what is required for quantum computation to become useful.
Don't hold your breath (or rather, everyone do hold your breath to keep that bubble from popping).
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