Question

Any physical meaning that the electric field operator consists of creation and annihilation operators?

Answer 1

You need both parts for the operator to be hermitian( observable). Similarly if you had a two photon process, the sum of two photon absorption and annhilation would be hermitian and the sum of Rabi (or Rayleigh) cross products would be hermitian.

Answer 2

You need both parts for the operator to be hermitian( observable). Similarly if you had a two photon process, the sum of two photon absorption and annhilation would be hermitian and the sum of Rabi (or Rayleigh) cross products would be hermitian.