Browsing by Author "Tufa, Merid"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Interaction of Subharmonic Light Modes with Three-Level Atom
    (Addis Ababa University, 2021-01-09) Tufa, Merid; Kassahun, Fesseha (PhD)
    In this dissertation we have studied the photon statistical and the quadrature squeezing properties of the two-mode cavity light available following the interaction of subharmonic light modes, emerging from a nonlinear crystal pumped by coherent light, with a single three-level atom in a closed cavity. The cavity is coupled to a vacuum reservoir via a single port mirror. We have considered the case in which the top and bottom levels of the three-level atom are not coupled by the coherent light emerging from the nonlinear crystal. Employing the pertinent Hamiltonian and master equations, we have obtained the equations of evolution of the expectation values for the cavity mode and atomic operators. Applying the steady-state solutions of the equations of evolution of the expectation values for the cavity mode and atomic operators, we have calculated the global mean photon number for the two-mode cavity light. The global mean photon number of the two-mode cavity light is found to be the sum of the mean photon number due to the subharmonic generation and the mean photon number emitted and absorbed by the atom. We have observed that the effect of the interaction of the subharmonic light modes with the three-level atom is to decrease the global mean photon number of the two-mode cavity light. This is due to the fact that the mean number of photons absorbed is greater than the mean number of photons emitted. Moreover, applying the time dependent solutions of the equations of evolution of the expectation values for the cavity mode and atomic operators, we have also obtained the local mean photon number for the two-mode cavity light. Our analysis shows that the local mean photon number of the two-mode cavity light increases with frequency and eventually approaches to the global mean photon number within a relatively small frequency interval. In addition, we have calculated the global photon-number variance for the twomode cavity light. We have noticed that the photon statistics of the two-mode cavity light is supper poissonian. Our analysis indicates that the global photon-number variance in the presence of the interaction is less than that in the absence of the interaction. This implies that the effect of the interaction is to decrease the global photon-number variance. Furthermore, we have determined the global quadrature squeezing for the twomode cavity light with arbitrary ordering of the two-mode vacuum reservoir noise operators. We have established that the two-mode cavity light is in squeezed state and the squeezing occurs in the plus quadrature. We have also found that the global quadrature squeezing in the presence of the interaction (43:5%) is less than the global quadrature squeezing (50%) in the absence of the interaction. In addition, We have seen that the maximum local quadrature squeezing for the two-mode cavity light is 60:8% at _ = 0:17 and eventually approaches to the global quadrature squeezing as the frequency increases. Finally, applying the steady-state solutions of the equations of evolution of the expectation values for the cavity mode operators, we have determined the global quadrature squeezing for the two-mode cavity light when the two-mode vacuum reservoir noise operators are in normal order. We have found that the global quadrature squeezing for the two-mode cavity light is 100% for c = 16 15 _ 1:067 and is 88:3% for c = 1:25 with the vacuum noise operators in normal order.