Although quantum computing is still in its infancy, the theoretical foundations have been developed and early experiments are giving cause for optimism. Researches foresee quantum computers with almost unimaginable computing power. It may still be early days for scientists, but it is actually possible to compute using the special physical properties of individual atoms and ions. Quantum scientists make use of the quantum state of, for example,metal atoms from the elements rubidium or potassium. Short laser pulses can affect these quantum states. The most important way in which they differ from electronic circuits is in the versatility of quantum states. The most important way in which they differ from electronic circuits is in the versatility of quantum states. They cannot be set to digital zero or one because they can hold these, and many other states in between, simultaneously.This means that, in principle ,they can perform several computations at the same time, whereas today's transistors are limited to performing tasks in sequence.