States can be represented as vectors |Ψ> = ½|+> + (i√3)/2|-> = ½ ( 1 ) + (i√3)/2 ( 0 ) = ( 1/2 ) ( 0 ) ( 1 ) ( (i√3)/2 ) Operators are matrices Showed how Â|Ψ>=|φ> translates to a matrix in the z basis (pic x2) Example with S𝓏 operator (pic) Example with S𝓍 operator (pic) Often we know operator but not basis. How to find basis? (pic) i.e. find the eigen-basis S|α>=λ|α> Only non-trivial if determinant is zero. Solve for basis. (pic)