Ruby laser is a three-level system.This paper utilizes theories of Kraus operator,to analysis the three-level system which is in the case of absorption as well as radiation .The object of the research is to probe into the transformation properties of density matrix.The result show that when particles transform from ground state to the second excitated state and from the second excitated state to the first excitated state at very high probability,the system forms reversion of particles and prepares for producing laser.It also show that when particles transform from the first excitated state to ...
