What is a Qubit?

A classical bit is a basic unit in digital world which can store a binary value 0 or 1.

What is different between a quantum bit and a classical bit, is that a classical bit is either in state 0 or state 1. In contrast, a quantum bit can be prepared in what is called a superposition state, which is somewhere in between 0 and 1.

The state of a qubit can be represented by α|0⟩+β|1⟩, a linear superposition of the two possible states.

|0⟩ and |1⟩ are the two orthogonal basis vectors that are encoded as:

|0⟩ = [1/0]

|1⟩ = [0/1]