两能级原子与单模腔场共振耦合系统中热态纠缠现象

Thermal Entanglement in a Two-level Atom Resonantly Coupled to Single-mode Cavity System

借助于共生纠缠度,研究了旋转波和非旋转波近似下共振Jaynes Cummings模型中二能级原子与单光子腔场的热态纠缠现象 结果表明:该共振耦合系统中,存在影响原子与单光子腔模纠缠的临界温度,当环境温度高于这一温度时,原子与腔场的纠缠特性消失 若只考虑实光子跃迁,这一临界温度仅与原子和腔场的耦合强度有关,随耦合系数的增大而升高;若将虚光场一并考虑,只要实光子跃迁强度与虚光子跃迁强度不相等,在一定的温度下能很好的保持原子与腔场的纠缠相干性,当二者相等时,即使在绝对零度下,原子与腔场也难以形成纠缠形式。

The thermal entanglement produced by resonant Jaynes-Cummings model with and without the effect of virtual-photon field is investigated. It is shown that there exists a critical temperature, above which thermal entanglement of atom and field mode vanishes. In the absence of virtual-photon field, the critical temperature increases with the increasing of the coupling constant between atom and cavity field. Thermal entanglement can be generated for sufficiently strong coupling under room temperature. In the presence of virtual-photon field, it is also shown that the critical temperature is determined by the processes of real and virtual photon transition. When the process of virtual photon transition is equal to that of real photon transition, no thermal entanglement takes place even if the setup is cooled to below the critical temperature.