三能级原子同时存在辐射和吸收时的量子相干性

量子位和环境的相互作用,将引起量子位能量耗散或相对位相改变,最终导致量子位由相干叠加态退化为混合态或纯态,这种现象被称为量子消相干.针对三能级原子同时存在辐射和吸收时的情况,基于量子力学和Kraus算子理论,利用约化密度矩阵方法,分析了三能级原子密度矩阵元的演化规律,从而研究该系统的量子相干特性.结果表明:初态处于相干叠加态的三能级原子,由于辐射和吸收,可能演化成相干叠加态、未完全混合态、完全混合态、纯态.

Coherence properties of radiation and absorption in the three-level atom

The interaction of the qubit with its environment induces the qubit dissipation or dephasing,which causes the qubit collapse from a coherent superposition state to a mixed or pure state.This process is known as quantum decoherence.The radiation and absorption of the three-level atom is studied.Basis on theories of quantum mechanics and Kraus operator and utilizing the reducible density rectangular method the transformation of density matrix of the three-level atom which simultaneously in the case of the radiation and absorption is investigated.The coherence properties of quantum states are also investigated.If the early state of the three-level atom is coherence state,it may evolve to the coherent state,the partial mixed state completely,the completely state,and the pure state.