Explicit Form of the Evolution Operator of Tavis-Cummings Model : Three   and Four Atoms Cases
  In this letter the explicit form of evolution operator of the Tavis-Cummings model with three and four atoms is given. This is an important progress in quantum optics or mathematical physics. 
Kazuyuki Fujii, Kyoko Higashida, Ryosuke Kato, Tatsuo Suzuki, Yukako   Wada