text: where ˆ*a*, ˆ*a*† are the annihilation and creation operators of the 
  ﬁeld mode inside the cavity, with the frequency ω, σ*j*
  *a*= 
  )*j*are the projection operators for the 
  ( 
  *a*
  | 
  | 
  jth atom corresponding to the upper and lower lasing levels, 
  )*j*and σ*j*
  | 
  *b*= ( 
  *a*
  i h 
  *b*
  *b*
  i h  | 