非旋波近似下双光子Jaynes—Cummings模型的量子特性

Quantum Properties of Two-Photon Jaynes-Cummings Model without Rotating Wave Approximation

在非旋波近似下对双光子Jaynes-Cummings(J-C)模型与单模相干态光场相互作用的量子特性进行了精确求解。对双光子J-C模型与单光子J-C模型量子纠缠和原子布居数反转的演化特点进行了对比,讨论了平均光子数、光场与原子之间的耦合强度以及失谐对量子纠缠以及原子布居数反转的影响,数值计算的结果表明,随着光场与原子之间耦合强度的增大,量子纠缠的周期性逐渐消失,随着平均光子数的增加,纠缠达到较稳定的最大值所需时间逐渐增大。无论耦合强度、平均光子数还是失谐的增大,由非旋波项产生的虚光子效应逐渐增强,量子纠缠演化曲线和原子布居数反转的塌缩区出现小锯齿状振荡。

Quantum properties of a two photon Jaynes-Cummings model（JCM） interacting with a single mode coherent light field is calculated mechanically without rotating wave approximation. The evolution properties of the two-photon JCM and JCM quantum entanglement and the atomic population inversion are contrasted. The effects of the mean photon number, the atom-field coupling coefficient and the detuning on the quantum entanglement and the atomic population inversion are studied. The numerical results indicate that, with the increase of the atom-field coupling coefficient, the period of the entanglement evolution disappear gradually, and it takes longer time for the mean entanglement to reach the maximum value with increasing of the mean photon number.The little indentation oscillation appears in the evolution curves of quantum entanglement and the collapse regime of the atomic population inversion, which is caused by virtual photon effect, weather increasing of the atom-field coupling coefficient or the mean photon number and the detuning.