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What is Quantum computer. i can't get right idea


faslan

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In a nutshell, using entangled states 2n different states can be simultaneously accessed using n register bits which resolve to a single measured state when the wave function collapses.

 

Currently this is infeasible. Efforts are on to replicate quantum gates, but like teleportation whether this is completely feasible is debatable. (at least at this juncture.).

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In a nutshell, using entangled states 2n different states can be simultaneously accessed using n register bits which resolve to a single measured state when the wave function collapses.

 

Actually in most of the qa I have studied you do not magically get the answer through a single measured state; you iterate the qa multiple times and work classically from the set of answers you have received.

 

Currently this is infeasible. Efforts are on to replicate quantum gates, but like teleportation whether this is completely feasible is debatable. (at least at this juncture.).

 

 

Not sure you are not being a little pessimistic there Petruska - there are papers out there describing use of quantum processors

 

http://arxiv.org/pdf/1201.1842v3.pdf

 

The R (8,2) computation used 84 qubits of which 28 were computational qubits. This computation is the largest experimental implementation of a scientifically meaningful adiabatic evolution algorithm that has been done to date

 

 

Our hardware is designed to implement QA using RF-SQUID flux qubits. Each qubit is a superconducting loop interrupted

by Josephson junctions, and the states |0〉and |1〉correspond to the two directions of circulating current about the loop.

 

This is all way beyond my pay-grade - but I am pretty sure these guys are claiming they have an actual physical working machine that relies on quantum properties.

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Oh didn't know bigger cores are still viable.

And how do you manipulate the superposition without measurement? Cause if don't observe, I thought they are not in a fixed state. I don't think you can work with them like this.

 

That's entirely possible. A "chip", if you will pardon the simplification, that does the quantum calculation and returns the result to a more traditional computer infratructure for consumption. In fact, I expect that to be a lot more likely that entire computers running on quantum based technology.

Yeah, After all the main point of quantum computers is their speed, the rest can stay the same as before.

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Actually in most of the qa I have studied you do not magically get the answer through a single measured state; you iterate the qa multiple times and work classically from the set of answers you have received.

 

 

Not sure you are not being a little pessimistic there Petruska - there are papers out there describing use of quantum processors

 

http://arxiv.org/pdf/1201.1842v3.pdf

 

 

This is all way beyond my pay-grade - but I am pretty sure these guys are claiming they have an actual physical working machine that relies on quantum properties.

 

Quantum registers would rely on superposition and a fuzzy state...which means they can be used to store data for more combinations per register than conventional electronic registers. Imagine what this would mean to a game like chess....even a brute force approach might yield tangible results. :unsure:

As far as I know (i accept that I am not a precept on the subject) the closest physicists have got to quantum circuits is using superconductivity in Canada where it was feasible to entangle a trivial number of photons. (i'm not sure of the exact figure though...). What the future entails is as much a conundrum to me as a Rubik's cube... :mellow: Your thoughts would be appreciated...

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Oh didn't know bigger cores are still viable.

And how do you manipulate the superposition without measurement? Cause if don't observe, I thought they are not in a fixed state. I don't think you can work with them like this.

/...

 

Sorry if I gave the impression you don't measure - what I meant to get across was that you do not measure to get a simple single collapsed answer. You set up the superposition, transform with unitary tranformation gates, measure, rinse and repeat - then classically manipulate the multiple answers. From hazy memory - for a quantum implementation of a factorisation algorithm you end up getting random multiples of factor from a period finding function, with large numbers of these you can then find the gcd classically and that is your factor (nb very simplified)

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