Photon occupation enhancement of emission
= Photon occupation enhancement of emission
{title2=$\Gamma_{\rm em}\propto n+1$}
The creation-operator <matrix element> $\langle n+1|a^\dagger|n\rangle=\sqrt{n+1}$ makes emission into a radiation mode proportional to $n+1$. The $n$ part is <stimulated emission> and the remaining part is <spontaneous emission>. Absorption has the corresponding occupation factor $n$.