The statistical and fluctuational properties of an electromagnetic field in a nonideal cavity are studied with the help of the collective two-atom Jaynes-Cummings model taking into account losses of photons and spontaneous radiation of atoms into bath modes. For the coherent state of the field and excited initial state of atoms, the general analytical expressions for the second-order field correlation function, the second-order squeezing parameters, and the squared field amplitude are obtained by solving the master equation for the density matrix. The statistics and the degree of squeezing of the cavity field mode are studied as functions of the initial field intensity and of the coefficients of the energy dissipation of the system. It is shown that, for the two-atom dissipative model, compared to the single-atom model, the type of field statistics can be changed and the maximal degree of short-term squeezing can be increased.
We study interaction between a pair of indistinguishable two-level atoms and the single-mode cavity field. It is supposed that the pair of two-level atoms is laser cooled and trapped into the ground vibrational state, in which vibrational quantum number
⟨nv⟩=0 . Two Jaynes–Cummings models are investigated. One is the Jaynes–Cummings model with intensity-dependent coupling and the another is the two-photon Jaynes–Cummings model of a pair of indistinguishable two-level atoms. It should be noted that in the present model, at initial moment
t=0 , in intensity-dependent Jaynes–Cummings model the cavity field is prepared in Holstein–Primakoff SU(1,1) CS, while in two-photon Jaynes–Cummings model it is prepared in the squeezed vacuum state. Moreover, at initial moment
t=0 , pair of atoms is supposed to be in the first excited state
∣e1⟩ in both models. By using exact analytical solutions for state-vectors of the coupled atom-field systems amplitude-squared squeezing of the quantized cavity field is examined as a function of the
∣ξ∣ parameter. In this situation, in both models higher-order squeezing has the tendency towards oscillations, but exact periodicity of these oscillations is violated by the analogy with the second-order squeezing.
There have recently been several proposals for generation of optical superposition states in the resonant atom-field interaction and more practically in microwave cavities. In the present paper we study the influence of the vacuum reservoir on properties of the near-superposition state of the cavity field which is described by the Jaynes-Cummings model at one-half of the revival time. Instead of introducing the cavity loss from the first instance of the atom-field interaction we consider the cavity loss only after the near-superposition state is produced and after the atom leaves the cavity. We solve the corresponding master equation with the initial condition being the Jaynes-Cummings field at one-half of the revival time. We find that under the influence of the vacuum reservoir the photon number distribution of the superposition state we study exhibits certain asymmetry around the mean photon induced by the decay process. We show that an analogous effect can be seen when the Jaynes-Cummings superposition state is amplified. For a basic test of our approach we study the dissipation and amplification of Fock states.
We have studied the influence of thermal photons on the symmetry between the field and atomic squeezing (SFAS) exposed in the resonant vacuum-field Jaynes-Cummings model with an initially coherent atom. We have shown that when the number of thermal photons ( N av ) is less than 0.01, the SFAS is not sensitive to the presence of thermal photons; when N av ⩾ 0.01, the broken SFAS can be seen; when N av ⩾ 0.1, the squeezed atom cannot radiate a squeezed field any longer. Also, we have discussed the possibility of detection of the boken symmetry in superconducting maser cavity.