What is a Quantumn Computer?

[MSNwar]

Should I save-up for one?

[FthrJACK]

Quantum computers use quantum mechanics to calculate problems. as the achitecture is so very small (as small as your gonna get!) its very very very fast. its also pretty complicated.

i wouldnt start saving just yet msnwar lol! it will be interesting to see them make it into peoples homes, also expect to see machines using not wires inside... but fiber optics within a few years.

to save me trying to explain quantum computers i copied and pasted this, its wording is beter than i could manage:

In a quantum computer, the fundamental unit of information (called a quantum bit or qubit), is not binary but rather more quaternary in nature.  This qubit property arises as a direct consequence of its adherence to the laws of quantum mechanics which differ radically from the laws of classical physics.  A qubit can exist not only in a state corresponding to the logical state 0 or 1 as in a classical bit, but also in states corresponding to a blend or superposition of these classical states.  In other words, a qubit can exist as a zero, a one, or simultaneously as both 0 and 1, with a numerical coefficient representing the probability for each state.  This may seem counterintuitive because everyday phenomenon are governed by classical physics, not quantum mechanics -- which takes over at the atomic level.  This rather difficult concept is perhaps best explained through an experiment

Read more over HERE

i also used to know of a page with a quantum computer simulator on it and you could use it to do very basic things, eg.. calculate numbers etc based on the algorythm quantum computers are based on.

Also i found this interesting idea, id recomend looking up on schrodingers cat, and if you can get the book its a good read!

John Cage's composition 4' 33" is a piano piece that is performed by not performing. The pianist goes through all the preliminary motions, but sits in silence for 4 minutes and 33 seconds -- after which, one assumes, the audience applauds. Two scientists are now aiming to produce a computer that works in the same spirit -- to give the answer without ever being switched on.

Like Cage's piece, this feat is not about doing nothing; it is about doing nothing in the time normally allotted for doing something. "Due time must be allowed for the machine not to run," say Graeme Mitchison of the University of Cambridge and Richard Jozsa of the University of Bristol, UK.

The researchers insist that this is not some surrealist form of computer science, but rather that it should truly be possible to determine the outcome of a computation while the machine stays off. The computer they have in mind is no ordinary desktop model but a quantum computer.

In theory, a quantum computer would be much faster than existing computers. It would exploit the principles of quantum mechanics to achieve massively parallel processing, performing many logic operations at the same time.

So far, demonstrations of quantum computing have been limited to the most rudimentary of calculations, involving only two or three bits of information. Extending this to the thousands or millions of bits needed for the computer to be practically useful is a huge challenge. Although there have been several suggestions for how a quantum computer might be built, no one is even close to doing it.

But imagine, say Mitchison and Jozsa, that such a computer exists. Quite apart from streamlining information technology, they point out, this hypothetical machine would highlight, "in a particularly poignant way," the counter-intuitive nature of quantum physics.

Quantum laws allow for the bizarre phenomenon of 'counterfactuality': one can glean information about a quantum event that did not actually take place.

Quantum systems can exist in two incompatible states at once, a condition known as 'superposition'. The most famous example is Schrödinger's cat, which can be both alive and dead if its fate is determined by a quantum superposition of two possible outcomes. A quantum computer uses such superpositions to enlarge its computational power. A superposition generally collapses into one state or the other if measured -- we can never actually 'see' a superposition.

Michison and Jozsa describe a scheme for probing all the possible states of a quantum computer, including that in which all the 'switches' are 'off' -- that is, in which the computer is not turned on.

In other words, although the computer's quantum circuits existed in a superposition of states while it was performing a computation, it is possible to collapse this into an identical state to that in which it never ran at all -- and, in so doing, to obtain the answer to the computation.

One interpretation of quantum superpositions is that they represent alternative worlds. When the collapse occurs, we end up in one of these worlds and the other becomes irrelevant to our own reality. But that parallel world nevertheless has, in some sense, a real existence. In this picture, a multiplicity of worlds is continually being generated by quantum events.

Mitchison and Jozsa's 'counterfactual computation' essentially taps into worlds in which the computer did run in order to extract the result into a world in which it didn't.

If a tree falls in the forest and nobody is there to hear it.... does it make a sound??

[MSNwar]

I want to be the first kid on the block with one of those babies.

The part about how a property can represent both 0 and 1 and the only difference is a mathematical element is intriguing. Star-Trek stuff.

Thanks

[MSNwar]

If a tree falls in the forest and nobody is there to hear it.... does it make a sound??

Now I understand the above statement you have made in the past. You are a very deep person Tris.

What scares me is i LIKE this stuff.

[FthrJACK]

ok... i think you got the idea. but im going to try and explain it in my own words anyway....

an atom can have multiple states, lets call them "on" and "off" and also "inbetween"

ok, as soon as you measure the atom to find out the state... it changes. bugger eh?

ok, so to find out if its on or off we have to use an equation, which looks complicated but isnt.. much. id explain the equation but its a long time ago since i read about this stuff... ill let you find it on some of the many sites out there on quantumn computing.

a good explanation about the atomic state and the equation can be found in the book "shrodingers cat"

the saying "if a tree falls in the forest, and nobodys there to hear it.. does it make a sound?" also is an explanation of this, for to find out you would have to measure the trees collapse somehow, and in doing so, change its state (ie its more likley to make a crashing sound)

oh.. ok i give up, hit google to learn more lol.

its late, and this is stuff i havent done in a long time, the atomic state, shrodingers cat and quantumn computers are all VERY closely linked to TELEPORTATION too. yes... star trek teleporters MSNwar! heh, its the same equation needed to find out the state of atoms to be teleported.

you cant measure the atoms of an object to be teleported because as soon as you do they change.

what they have to do is make an atom for atom copy of the object using the equation then destroy the origional. Teleporters have already been built and teleported atoms across a lab. it will be many many many years before they are teleporting apples and things, let alone people. i wouldnt expect that in my lifetime... unless someone makes a huge breakthrough.

Quantumn computers would push teleportation on a long way i expect

[LS_Dragons]

Beam me over to Tris's house for a pint, Scottie

LS_Dragons

[FthrJACK]

i was waiting for you to get in on this thread LS.... but i thought it would be something usefull!! doh