Abstract:

We investigated the changes of the WignerYanase information in the processes of the spontaneous emission of a twolevel atom system, and calculated the WignerYanase information for the reduced density matrix of the atom and that for the quantum radiation respectively. Our investigations show that both of them depend on the expectation of 〈S_z〉. And the WignerYanase information for the radiation field reach the maximum when the atom stays in the ground state. Additionally, the results also show that both the atom and the field will not simultaneously become the maximal mixed state.

Key words: two-level atom, spontaneous emission, Dicke mode, Wigner-Yanase skew information, mixed state