The Study On The Phenomenon Of Quantum Decoherence

Concerning the transition from the quantum world to the classical world,people putforward many kinds of explainations,the most famous among them is the theory of thequantum docoherence.The reason of the loss of quantum coherence of macroscopic objects isdue to their coupling with the environment,Therefore a perfect knowledge of the mechanismof decoherence is crucial for the understanding of the quantum-classical transition .In this paper,we mainly study in the two-mode squeezed states,the dynamical evolutionof the motion of C.M of a couple of atoms,and discuss in the vacuum electromagnetic fieldhow the spontaneous radiation of a couple of atoms induce the decoherence for the motion ofC.M of this pair atoms.Firstly,by negelecting muti-photon process as the higer orderapproximation,we simply the model greatly.Secondly,we study in detail by considering therealistic environment formed by the photons in spontaneous radiation,the time evolution ofthe spatial states of the C.M of the two atom system.Finaly,we calculate when reducedfactor γ = 0,the reduced density matrix of the relative position.By the disappearance of theoff-digonal element,we explain the phenomenon of quantum decoherence induced by theatomic spontaneous radiation.Through these researches,we demonstrate the essence of the environment-inducedquantum decoherence.