Web Quantum Computer Simulator

Heraklit writes "As reported on Heise News, the Frauenhofer Institute of Computer Architecture and Software Technology has made available the first online quantum computer simulator - it will be simulating up to 31 quantum bits, for testing new advanced quantum algorithms. Behind the scenes, it is a 32 node Athlon 3200 Myrinet Linux Cluster with 56GByte RAM! Now imagine the computing power of a few hundred qubits, if ever constructed..."

Comments

Qbit algorithm explained...

[Anonymous Coward]

The algorithm in psuedo-code:

int qbit[32];

for ( i = 0; i < 32; i++ )
qbit[i] = (rand() >>30) & 0x01;

Nice rack.

[Anonymous Coward]

Nice rack, seriously. Clean, uncluttered.

Finally...

[bairy]

A "PC" that just scrapes Longhorn's requirements.

Quantum Observations

[Nom du Keyboard]

Well, there goes my private encryption key.

The only question left is, can a Quantum Computer Simulator handle the /. effect?

Re:Quantum Observations

[shadowcabbit]

The only question left is, can a Quantum Computer Simulator handle the /. effect?

Maybe, maybe not.

Re:Quantum Observations

[WarriorPoet42]

It both can handle /. and cannot handle /. This is known as the CowboyNeal's Cat Effect.

no fair!

[maxbang]

You changed the outcome of the loading time of the page by posting a link to it!

powerful only for certain algorithms

[Anonymous Coward]

'Now imagine the computing power of a few hundred qubits, if ever constructed...'

A few hundred qubits would be very powerful at factoring numbers and other such specialized algorithms. But as far as linux and other "normal" software goes, a few hundred qubit computer won't be any better than a few hundred bit software.

If the Q-Bit had gone to the other processor

[Nom du Keyboard]

32 node Athlon 3200 Myrinet Linux Cluster with 56GByte RAM!

If that had been a 32 node Itantium cluster, Intel could have boasted of doubled Itantium sales for that quarter.

So... I did my little quantum calculation deal

[strictnein]

and the answer I got was....

I don't know. I don't even know what the fuck I did. Just pushed buttons and two minutes later it told me I was done! THE QUANTUM POWER IS AMAZING!

...simulated?

[Cyclotron_Boy]

The scaling is not 1:1, so while it takes 32 Athlon processors with 56GB of ram, the processing power of 31 qbits is not that of the 32-processor cluster. This is an emulator, so the actual 31-qbit probably isn't quite as powerful as the hardware required to accurately mathematically model it. So while the computing power of a few hundred real qbits might be impressive, the computing power required to simulate those few hundred qbits would be extremely impressive.
-F

Re:Finally...

[B3ryllium]

Sorry, if you just imagine playing Duke Nukem Forever, you collapse it into a wave function and the game never gets finished.

Or something. Look, a monkey!

Life, The Universe, & Everything

[Nom du Keyboard]

And this quantum computer simulator contained the whole answer to Life, The Universe, and Everything...

Until somebody went and looked at it.

(Or does that need 42 Q-bits?)

Re:Life, The Universe, & Everything

[Elder Entropist]

Something else that blew my mind with Douglas Adams' work and quantum:

In one of the books (Life the Universe, and Everything?) he explains about how the infinite improbability generator works, and he states that an artifical brain (Bambleweeney Vector Plotter?) is connected to a really hot cup of tea.

One of the problems with quantum computers is decoherence - isolating the qubits from the environment. I was reading an article where they were discussing a strategy for this by isolating the qubits in a fluid that had a strong random component to it, but where the many interactions averaged out to zero. A fluid with lots of brownian motion - in other words, a hot cup of tea would do.

Re:wow!!!

[zeath]

Unfortunately, quantum computers aren't as powerful to the giddy consumer as that cluster describes. They're capable of doing repetitive, simple mathemetical tasks simultaneously on a large number of values. It's extremely complicated how that works, but I have it written in this paper (pdf) that I wrote a few years ago. The paper was focused primarily on quantum physics for the first half (also interesting, and related to the story ran a few weeks ago on the red laser and the parallel universe theory), while the second half deals with explaining how the quantum registers work. It starts in the second paragraph of page 3, though a few terms reference previous topics from the paper. It's only a few pages long and it'll explain a lot of things (some things more technical than others) that none of the articles explained. Especially pay attention to the first full paragraph on page four, which I'll quote here:

Richard Feynman was one of the first to see the potential in quantum superposition for solving such exponentially complicated problems much faster. For example, a system of 500 qubits, which is impossible to simulate with any computer today, represents a quantum superposition of as many as 2^500 states. Each of these states would be equivalent to a single list of 500 1's and 0's in a classical computer. A single quantum operation on such a system would simultaneously operate on all 2^500 states; with a single tick of the quantum computer's clock, the operation would compute not just on one machine state, as our serial computers do, but on all 2^500 machine states at once. Eventually, observing the system would cause it to reduce into a single state corresponding to a single answer, a single list of 500 1's and 0's, as measured by an axiom of quantum mechanics. A classical super computer would take approximately 10^150 separate processors to accomplish this task in the same amount of time (which is, of course, impossible).

What I can explain without too much trouble is that the cluster is merely emulating the abilities of a quantum computer. A quantum computer, conversely, would be incapable of matching the performance of, say, seti@home on all of those machines. Emulation is taxing on any system - just ask the people who are using PearPC on their brand spankin' new computers only to get sub-G3 performance out of OS X.

Re:For the quantumly challenged amoung us

[NonSequor]

Basically this stuff can't be done in polynomial time. For all quantum algorithms you start by setting a bunch of qubits into a uniform superposition of states (e.g. if you do this to 8 qubits and then measure them, you will be equally likely to get any number between 0 and 255 as your result). Then you can use these qubits as input into a function and effectively calculate the value of that function over every possible value of the input. The trouble is that you don't get 2^n different values of the function, you get a superposition of 2^n states. When you measure the output, you'll only find out one of the values of the function. So in order to get a working quantum algorithm, you have to manipulate the quantum state until you have a high probability of measuring the state you want.

Quantum computing has other complexities. Every function must output as many qubits as it has for input. It's also impossible to make a copy of a qubit without altering the original qubit. This means that in any quantum programming langauge, all funciton parameters must be passed by reference. All functions must be invertible. This can be generally accomplished by leaving the inputs unaltered and writing the output to some scratch qubits which are set to 0 beforehand.

If you want to learn more about quantum algorithms, I suggest you read up on Grover's search algorithm. It's much simpler than many quantum algorithms and it's also proven very adaptible to other situations.