Quantum register

A quantum register (also known as a qregister) is the quantum mechanical analogue of a classical processor register.

A mathematical description of a quantum register is achieved by using a tensor product of qubit bra or ket vectors. For example, an n qubit quantum register is described by an element $|\Psi\rangle=|\psi\rangle_{1}\otimes|\psi\rangle_{2}\otimes\ldots\otimes|\psi\rangle_{n}$ in the tensor product Hilbert space $\mathcal{H}=\mathcal{H}_{1}\otimes\mathcal{H}_{2}\otimes\ldots\otimes\mathcal{H}_{n}$