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If i have an arbitrary ket then i know it can always be expressed as a linear combination of the basis kets.I now have an operator A which has 2 eigenvalues +1 and -1.
The corresponding eigenvectors are | v >+ = k | b > + m | a > and | v >- = n | c > where | a > , | b > and | c > are linear combinations of the basis vectors.
The arbitrary ket is expressed as | ψ > = a | a > + b | b > + c | c > where | a |2 gives the probability of a measurement giving the eigenvalue corresponding to | a >. A question asks what is the probability of measuring the eigenvalue +1 . It gives the answer as | b |2 + | a |2 .
Finally to my question ; how or why does the expansion theorem apply to this situation as the eigenvector | v >+ only exists as a combination of | a > and | b >
Hoping you can understand my question. Thanks
The corresponding eigenvectors are | v >+ = k | b > + m | a > and | v >- = n | c > where | a > , | b > and | c > are linear combinations of the basis vectors.
The arbitrary ket is expressed as | ψ > = a | a > + b | b > + c | c > where | a |2 gives the probability of a measurement giving the eigenvalue corresponding to | a >. A question asks what is the probability of measuring the eigenvalue +1 . It gives the answer as | b |2 + | a |2 .
Finally to my question ; how or why does the expansion theorem apply to this situation as the eigenvector | v >+ only exists as a combination of | a > and | b >
Hoping you can understand my question. Thanks