What are Quantum Computers?
Quantum computers are not that different from normal computers outwardly, but they are in the sense that quantum theory is the basis on which these computers operate. The end result is that they are put together in a completely different way.
A normal computer operates on the basis of units known as bits. Each byte in a normal computer can only be one of 0 or 1 and nothing else. No matter how many bytes you have, each computer at a single point in time can only occupy one combination of these bytes in order for the programming to actually work.
A quantum computer is different from this because of a principle in quantum mechanics known as superposition. If you think back to your high school science courses, you may have learned about superposition when looking at how waves like light and sound waves move from one point to another. Quanta can also be in superposition with respect to each other and the end result is that the quantum bits that make up the computer can actually be 0, 1 and any superposition of the two.
The more quantum bits (also known as qubits) that you have, the more possibilities they are. Because you are dealing with superposition, it also means that the different positions can be occupied simultaneously. Whereas a simple 8-bit computer can only occupy one of the 256 positions generated by those 8 bits at once, the same 8-bit quantum computer could occupy all 256 qubit positions at once.
The end result is that quantum computers can be much more efficient than their conventional computer counterparts. Although quantum computers are still in their infancy, as the technology improves eventually it will become true that these computers will be able to calculate faster than the computers we have today. When that happens, the 3.0 GHz speed of a personal computer that we brag about now will be nothing in comparison to the new quantum computer models that become available on the market.