This spin-1/2 particle which behaves in a quantum manner could be the fundamental building block of a Quantum computer. We could call it a qubit, to denote that it is analogous in some ways to a bit in a classical computer. Just as a memory register in a classical computer is an array of bits, a quantum memory register is composed of several spin-1/2 particles, or qubits. There is no particular need for the spin-1/2 particle, we could equally well use a Hydrogen atom, and designate its electron being measured in the ground state to be the 0 state, and it being in the first excited state to be the 1 state. There are a multitude of possible qubit representations that will work. For simplicity only the spin-1/2 particle will be discussed from here on.