Читать книгу Quantum Mechanics, Volume 3 - Claude Cohen-Tannoudji - Страница 31

Using creation and annihilation operators makes it much easier to deal, in the Fock space, with physical operators that are thus symmetric (§ C-4-a-β of Chapter XIV). We first study the simplest of such operators, those which act on a single particle and are called “one-particle operators”.