A spin-half operator is .

PHYSICS · Multi-part · Fermi University Physics · Mathematical Methods for Physics · Quantum Mechanics · The formalism of quantum mechanics

The Structure of Quantum Mechanics, Ch Observables, spectra and the spectral theorem

Problem

A spin-half operator is A^=∣ ⁣↑⟩⟨↓ ⁣∣+2i∣ ⁣↓⟩⟨↑ ⁣∣\hat A=|\!\uparrow\rangle\langle\downarrow\!|+2i|\!\downarrow\rangle\langle\uparrow\!|. ((a)) Write the matrix Amn=⟨m∣A^∣n⟩A_{mn}=\langle m|\hat A|n\rangle in the basis {∣ ⁣↑⟩,∣ ⁣↓⟩}\{|\!\uparrow\rangle,|\!\downarrow\rangle\}. ((b)) Use (A^†)mn=Anm∗(\hat A^\dagger)_{mn}=A_{nm}^* to write the matrix of A^†\hat A^\dagger. ((c)) Decide whether A^\hat A is Hermitian, and whether it is unitary.

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