Quantum computers are the next generation in computing, and they will raise the bar so incredibly high, it will be hard just to adapt to their computing power. A quantum computer relies on the intriguing and hard to comprehend phenomena in quantum mechanics, and uses qubits instead of bits. Why is this going to rock our world? Well… quantumsystem.info
Have you ever heard of entanglement? Entanglement is a state of a quantum mechanical state that allows a channel for quantum information that just wouldn’t be possible for “classical systems”.
A classical computer has its memory made out of bits, where each bit can be 1 or 0, while a quantum computer maintains a series of qubits where a qubit can be a 1, a 0, or any other superposition between them. If you have n qubits, then you could have any superposition of the 2n, while in a classical computer you could just have one of these states. Measuring the qubits would produce a classical state of only n bits, but such an action would also destroy the quantum state (the laws of the quantum world are pretty messed up). We can think of the system as being exactly one of the n-bit strings-we just do not know which one. For example, a 300-qubit quantum computer has a state described by 2300 (approximately 1090) complex numbers
Although it is still only in its infancy, quantum computers show great promise, and a rapid development, being backed by many – you’d expect that from a technology that will probably change the world as we know it. Just think about it – astronomy, medicine, math, physics, it could all sky rocket, because a lot of today’s technology relies on software, computer simulation models, or massive calculation.
Aside from the technical difficulties, the most major problem is going to be the quantum decoherence. This usually means isolating the system from its environment as the slightest interaction with the external world would cause the system to decohere.
All in all, they will definitely bring a new spin to the world of computers, but even though significant developments have already been made, don’t think they will just pop up in a matter of weeks. It will probably take some 5 years until we have a decent quantum computer, and it will take even more time until they will start rocking the world, but sooner or later, they will.