Machine-translated by Google. Questions are authored in English.
Top

Discussion

For any operator A, i (A+ - A) is :

  • A.Hermitian
  • B.Anti-Hermitian
  • C.Unitary
  • D.Orthogonal

Answer: A

The operator \(i(A^{+} - A)\) is Hermitian.

Take the Hermitian conjugate, using \((cX)^{+} = c^{*}X^{+}\) and \((A^{+})^{+} = A\):

\[ \begin{aligned} [i(A^{+} - A)]^{+} &= -i(A - A^{+}) \\ &= i(A^{+} - A) \end{aligned} \]

The operator equals its own conjugate, which is the definition of Hermitian. The bracket \(A^{+} - A\) alone is anti-Hermitian, and multiplying an anti-Hermitian operator by i makes it Hermitian. Unitarity (\(U^{+}U = 1\)) and orthogonality are different properties that do not follow for an arbitrary A.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.