Stimulated emission by two-level atoms pumped to the upper level

► We have considered N two-level atoms, in a closed cavity, pumped to the upper level by means of electron bombardment. We have somehow managed to incorporate the effect of the pumping process in the equations of evolution of the atomic operators. ► We have carried out the analysis of the two-level laser by putting the noise operators associated with a vacuum reservoir in normal order. This leads to normally-ordered quadrature and photon-number variance. ► We found that the two-level laser operating well above threshold generates coherent light and the same laser operating at threshold generates chaotic light.