辐射场中二能级原子的量子态保真度

Fidelity of two-level atom's quantum states in radiation field

利用半经典理论和量子理论研究辐射场与二能级原子(量子位)的相互作用,给出二能级原子的量子态保真度表达式。讨论了不同的原子初始态条件下,半经典理论中辐射场强度对量子态保真度的影响和量子理论中辐射场光子数对量子态保真度的影响。结果表明:在半经典理论中,当原子与辐射场发生共振相互作用时,初始处于叠加态的原子的量子态保真度与辐射场强度无关;原子的量子态保真度随时间呈周期性演化,其演化的频率受辐射强度或光子数调制。此外,选择适当的失谐量,能够有效地改变量子信息的保真度。

The interaction between radiation and two-level atom was investigated by semi-classical theory and quantum theory respectively. The fidelity of the two-level atom＇s quantum state was written out The influences of the radiation intensity in the case of semi-classical theory and the photon number of the radiation in the case of quantum theory on the fidelity were discussed for different atomic initial states. It is found that the fidelity of quantum state is independent of radiation intensity when the atom is initially in a superposition state and the atom interacts resonantly with the radiation field in semi-classical theory The atom＇s quantum fidelity evolves periodically with time, and its frequency is modulated by radiation intensity. Furthermore, it can effectively change quantum information fidelity when the appropriate detuning is selected.