**Figure:** Opening Screen for QEDApp

This program is similar to JCapp in its construction, as in Figure . The difference between these two programs is that QEDapp solves the completely quantized model. Its algorithm is based on eq:j4. The solution of this problem has been limited to a two level atom and field. In this situation, a simple symmetry in the structure of the density matrix arises which allows one to solve only eight equations; however, for larger numbers of field states, the entire density matrix must be solved. This problem for even twenty field states is beyond the computational power of a personal computer. Nonetheless, this limited model does illustrate some of the basic similarities and differences between the fully quantized model and the Jaynes--Cummings model.

QEDapp has the same controls as JCapp with three exceptions. The field window has been omitted; however, the probability of both the field and atom states may be plotted in the analysis window. The user has the ability to set the diagonal elements of the density matrix to any value. The ** State** dialog on the ** Parameters** menu provides this ability. This dialog has four entries for a0, b0, a1, b1 where a/b is the lower/upper state of the atom, and 0/1 is the lower/upper state of the field. The ** Numerical** menu item allows the user to toggle the algorithm between the RWA and a full solution. Remember that the Jaynes--Cummings model is merely the fully quantized system with the RWA. Initially, the RWA has been turned on.

Wed May 17 14:34:24 EDT 1995