频率变化场J-C模型中的量子态保真度

Fidelity of Quantum States in the Jaynes-Cummings Model with a Time-varying Frequency Field

利用Jaynes-Cummings模型,考虑场频率受微扰的情况,在旋波近似下研究了二能级原子与单模辐射场相互作用系统中量子态保真度的演化.利用数值计算方法给出量子态保真度随时间的演化曲线.研究了场频率随时间正弦函数形式变化对系统、光场和原子的量子态保真度演化的影响.结果表明:场频率随时间正弦函数形式变化对系统和光场的量子态保真度的演化的影响很小,但对原子的量子态保真度的演化有显著影响.

Using the Jaynes-Cummings model, the dynamical properties of the fidelity of quantum states in the system that consists of a two-level atom interacting with a single-mode field are studied. The frequency of the field varying with time in the form of sine is considered. The results obtained by numerical calculations show that the time-evolution behavior of the fidelities of field and system are not influenced by the frequency variation of field,but the time-evolution behavior of the fidelity of atom is modulated by the frequency variation of field. The larger the amplitude of the field frequency variance u is, the stronger modulation interaction of the field frequency variance is. When the amplitude u is larger than a fixed value, the time-evolution behavior of the fidelity of atom will display periodic oscillation behavior. Its Oscillation period is in agreement with the period of frequency varying.