How does a quantum computer work and what would its applications be?

Answer 1

These are still in the pure research stages yet and there is no complete one that I know of. You'd use them just like any other computer. A quatum computer just uses quantum phenomenon to perform switching and storage.

Here's a site;

http://www.cs.caltech.edu/~westside/quantum-intro.html

Answer 2

I recommend this explanation of the workings of a quantum computer:
http://www.cs.caltech.edu/~westside/quantum-intro.html

The appliations of quantum computing include integer factorization, simulating quantum mechanics, and the discrete logarithm problem:
http://en.wikipedia.org/wiki/Discrete_logarithm

The most popular of these three is of course, integer factorization. A shocking amount of modern cryptography lies on the assumption that there is no known way to easily factor very large numbers with a classical computer. Quantum computers can do this with their eyes closed.

Cheers,

Answer 3

A quantum computer would be perfect at code breaking by brute force as it could calculate all the possible passwords/codes at the same time.

It could also set codes that would be unbreakable...and you would know if anyone had been trying to break them.

Answer 4

look it up in http://www.wikipedia.org