首先研究了处在热平衡条件下的Λ型三能级原子与环境(热辐射场)的涨落耗散，利用马尔科夫近似下的系统－源相互作用理论精确推导出Λ型三能级原子衰减态密度矩阵元的演化方程组。在此基础上进一步研究了热平衡稳定态。最后利用全量子理论对光场失谐时电磁诱导透明中探测光的量子噪声进行了研究。结果表明量子噪声主要来源于激发态的原子态密度以及驱动光的失谐量，因此在冷原子系统中实现EIT并且减少驱动光的失谐量将是控制量子噪声的关键。

The fluctuation-dissipation between three-level Λ-type atoms and environment(thermal radiation field)in thermal equilibrium is discussed firstly. The equations of motion for the atomic density matrix elements are derived by using the system-reservoir interaction theorem in the Markovian approximation. The thermal equilibrium steady-state is obtained. The quantum noise of probe laser in the electromagnetically induced transparency(EIT)is studied by using the fully quantum theory. It is found that quantum noise comes from the excited-atom density and the detuning of drive laser. So realizing EIT in the cold atomic system and reducing the detuning of drive laser are the keys to control quantum noise.