:A qubit isn't to be confused with a cubit, which's an ancient measure of length. A quantum bit or qubit ['kju.bɪt] (sometimes also qbit or qu bit)'s a unit of quantum information. That information's described by a state vector in a two-level quantum-mechanical system, which's formally equivalent to a two-dimensional vector space over the complex numbers. In addition, the qubit should've these properties Scalability (long coherence time) Can be initialized Controlled unitary transformati… (More on Qubit)