# US boffins build, test working 2-qubit quantum processor

Federal boffins in America say they have built the first computer processing device able to handle quantum-mechanical numbers expressed as "qubits". Whereas a regular bit is either 1 or 0, a qubit can be 1, 0 or some of both just as a metaphorical cat in a box may be dead, alive or in a mysterious semi-undead waveform zombie …

#### Encryption

"If many such devices could be successfully hooked together to create a quantum computer, various major consequences could be expected - not least the breaking of encryption regarded today as completely uncrackable"

and creating new encryption that will be uncrackable by even quantum computers....?

#### Is there a Murphy's Law over the other side of the Pond? Or a Sod's Law if IT's a Buggy Project.

"Whereas a regular bit is either 1 or 0, a qubit can be 1, 0 or some of both just as a metaphorical cat in a box may be dead, alive or in a mysterious semi-undead waveform zombie condition. ...... "This is the first time anyone has demonstrated a programmable quantum processor for more than one qubit," says NIST postdoc researcher David Hanneke. "It's a step toward the big goal of doing calculations with lots and lots of qubits. The idea is you'd have lots of these processors, and you'd link them together.""

Epic Result, chaps ..... Chaos Squared, with the Left not knowing what the Right is doing and the Middle not giving a Fiddlers because they're all doing IT Together Different and Screwing someone else for Themselves. It is bound to be a Smashing Success.

Might I suggest its Colossal Reserve Power for Federal Disaster Recovery Programs and the Stimulation of Fisci which are all heading Due South this Deep Winter of Virtual Discontent.

"and the US military are also known to be interested in the idea." ... Well, blow me down with a feather, who would have thought it, whenever causing bits of chaos to churn into dollar denominated destruction is so very much not their thing.

Does anyone else think that it is gonna be a bugger to Properly Program to does it is told rather than do as IT wants? :-) ...... unless you have the Knack/Crack, that is.

#### Nice. But what does "programmable" man...

...as this is the most analog computer possible - there are no possible discontinuities and everything is smooth, linear transformations.

"a qubit can be 1, 0 or some of both just as a metaphorical cat in a box may be dead, alive or in a mysterious semi-undead waveform zombie condition."

You are looking for the word "Bloch Sphere": http://en.wikipedia.org/wiki/Bloch_sphere

#### Fair enough..

"If many such devices could be successfully hooked together to create a quantum computer, various major consequences could be expected - not least the breaking of encryption regarded today as completely uncrackable."

I don't doubt that, but the real question is - can it play Crysis on full settings?

#### Does Heisenberg apply

The answer is only 79% acurate?

Does this mean that you can either know the answer, or you can know the accuracy of the answer, just not both at the same time?

#### Yes2ID?

"At the moment, the 2-qubit processor is only 79 per cent accurate."

The Home Office have apparently expressed a great deal of interest in such a high level of accuracy.

#### It's not just the military who are interested

If I can get a computer that can be made totally secure, i.e. with unbreakable encryption, I'll take it.

Then the nosey bastards in government can't read my traffic.

#### Quantum Moore's Law?

The Moore's Law for quantum computation seems to be, the power of quantum computers will improve by 1 qubit each 5 years.

Adding a qubit multiplies the complexity of the quantum system, thereby multipying the complexity of the control system. So while the control system gets exponentially better over time, the qubit system only gets linearly better.

But the qubit system can solve exponentially complex problems. An N-bit quantum system is as good as a 2^N-bit classic system, say.

But what good is that if the N-bit quantum system needs a 2^N-bit control system?

And that's ignoring the 1/5 chance of a wrong answer with the existing system. This makes thermionic valves look like a model of reliability.

#### Comming soon to XBox Quantum...

from the creators of Guess the Bit comes the all new Guess both the Bits! bit reading chemical laz0r not included (probably).

#### So, what sort of results do you get?

Instead of 1+1 = 2, do you get something like 1+1 = somewhere between -infinity and +infinity?

...Or A xor B = Teacup?

Seriously, what does a result look like from a quantum computer? Or can it not be written down without opening up a rip in the time matrix and sucking up the whole universe into an infinitely small quantum giraffe?

#### @Michael Shaw: computation V accuracy

I think you're asking a question I've been wondering about ever since this quantum crap started, namely that they were promising too much to be credible. Quantum computation apparently grows (from what I've read) non-linearly as qbits are added [*], yet accuracy is always the problem. I've long wondered if there's a fundamental link between computation and accuracy in that there's an upper limit to one which, if exceeded, starts to eat into the second. But no-one's ever raised this point that I've seen. Anyone here know any better?

[*] for a given unit of computing power, you can expand this by a cube power in 3 dimensions ie. a box 1 foot per side holds 1 unit of computation, double the boxes in each direction & you get a box 2 foot per side & holding 8 units of computation. You can't do better in 3d space, but quantum promises a much higher scaling, so there's a conflict.

#### Q: What is 2 + 2 ? A: 4

" At the moment, the 2-qubit processor is only 79 per cent accurate."

Q: What is 2 + 2 ?

A: 4.

Q: What is 2 + 2 ?

A: 4.

Q: What is 2 + 2 ?

A: 3.

Q: What is 2 + 2 ?

A: Twelfty?

Sounds great.

#### LOL

"in a mysterious semi-undead waveform zombie condition"

OK, so who do I bill for the new keyboard as it is now covered in Coke!

Funniest thing I have read today!

B.

#### Enough with the semi-dead cat already!

Schrödinger's cat is intended to illustrate the paradox of the Copenhagn interpretation of quantum mechanics, and has bugger all to do with QM in this case.

#### As Douglas Adams would say

The problem with an immense Quantum Computer is that you could only know either the question you asked it, or the answer it gives, but not both at the same time. Particularly frustrating if it gave you the answer "Yes, he exists" and you didn't know whether you asked about God, Santa Claus or the tax man.

Nonetheless, I think this project should be turned over to the little white mice.

#### A 4 year math course...

Apparently the only advantage of all this is that it's faster than 2 state.

When we find ENTANGLEMENT in our 2 state memory, we have to replace it.

Possibly we could also build a qubit computer by merely saving all our defective ram sticks and assembling them all in a closed box, togetrher with a cat, of course..

#### Quantum LMAO

for n = 0 to 2

Print "Hello world"

next n

end

..run

Hello world

Goodbye world

Who needs the world anyway? Humans are no longer required. Bombing will commence in three minutes.

Just wait until the AI guys have a play with this compute power and the 'third state' complexities.

I will LMAO in the 0 and 1 state whilst it lasts.

#### "But the qubit system can solve exponentially complex problems"

No. The complexity class you are referring to is Bounded-Error Quantum Polynomial-Time (BQP). This complexity class is a letdown as it is only somewhat more powerful than P:

http://en.wikipedia.org/wiki/BQP

#### Hmm...

As Heisenberg once said: "I'm not sure about this".

Pauley was less equivocal. His take was: "Leave me out of it".

#### I understand

the folks at CERN are interested in using this as a control system.

It seems clear from reading this article that we would then have countervailing rifts in the reality/unreality interface which would then create a vortex in probability space of sufficient size to encompass much of Switzerland.

One shudders to imagine the worm-holey pseudo-fromagerie soon to be unleashed upon a sleeping world.

I for one welcome our coming fuzzily logical cheesy overlords.

#### learn how to think people!

" At the moment, the 2-qubit processor is only 79 per cent accurate."

Q: What is 2 + 2 ?

A: 4.

Q: What is 2 + 2 ?

A: 4.

Q: What is 2 + 2 ?

A: 3.

Q: What is 2 + 2 ?

A: Twelfty?

Sounds great.

Oh dear, miss the point and the boat. it doesn't matter what the factor of acuracy is as long as it is greater than 50%. It's a quantum computer, calculate 2+2 50 trillion times and use the answer that comes up most often, it will be 100% correct every time :-) As the preceding admittedly few calcualtion demonstrate clearly, the correct answer is 4.

#### Great. How useful!

IIRC, about the only thing we can do with a quantum computer that we cannot do about as well with a normal one is to crack public key cryptography. That is, some of the systems only, and and of course a computer with around 3000 qubits would be needed.

"Quantum computing" sounds really good, but it is pretty much useless.

PH, because she looks good too, but...

#### Re: learn how to think people!

Actually, it could be wrong 50 trillion times in a row, then right for the next 200 trillion or so. But the odds of that are 2^telephone_no:1 against.

(And why would anybody want to learn how to think people?)

#### Grover's algorithm

You can do more than factorise prime numbers, you can, using Grover's Algorithm search an unordered list in O(n^0.5) time.

If only I didn't think of the Sesame Street muppet http://en.wikipedia.org/wiki/Grover every time this comes up :-)