Unitary matrices

From SklogWiki

A unitary matrix is a complex matrix $U$ satisfying the condition

$U^\dagger U = UU^\dagger = I_n\,$

where $I$ is the identity matrix and $U^\dagger$ is the conjugate transpose (also called the Hermitian adjoint) of $U$ . Note this condition says that a matrix $U$ is unitary if and only if it has an inverse which is equal to its conjugate transpose $U^\dagger \,$