纠缠动力学过程中反旋转波项效应的研究

Quantum entanglement is one of the most striking consequences of nonlocal and nonclassical quantum correlation. An understanding of entanglement evolution and entanglement transfer between qubits is of fundamental interest in quantum information processing. The counter-rotating terms are the energy nonconserving terms in quantum optics. They correspond to the processes in which the atom jumps to an excited state and a virtual photon is emitted, followed quickly by the reverse process in which the atom jumps back to the ground state and now absorbs a photon. These terms are often dropped in the calculatin equations and the Rotating Wave Approximation (RWA) is used when the interaction is near resonant and weak. In fact,these counter-rotating terms neglected in the previous studies can have a large impact on the short-time evolution, especially when the interaction between atom and field is far-resonant and strong. In this project, we focus on the effects of the counter-rotating terms on entanglement dynamics. The following items are included: 1. Investigating the effects of the counter-rotating terms on the entanglement dynamics of two independent qubits; 2. Considering the dipole-dipole interaction between atoms and investigating the effects of the counter-rotating terms on the entanglement evolution of two interacting qubits with collective effect; 3. Entending two-qubit entanglement to three-qubit entanglement or multipartite entanglement. Investigating the effects of the counter-rotating terms on the entanglement evolution and transfer process of the three-qubit entanglement or multipartite entanglement. The meaning of this project is that understanding the coherent effects of the counter-rotating terms and the rotating terms on entanglement dynamics, and illustrating the physical mechanisms of the effects of the counter-rotating terms.

量子纠缠指两个或多个量子系统之间非定域非经典的强关联，量子比特的纠缠动力学演化在量子信息学中具有非常重要的作用。反旋转波项代表能量不守恒项，表示虚光子快速发射与吸收过程，在处理近共振弱相互作用问题时，可以忽略虚光子过程，采用旋转波近似方法处理。但是，当考虑瞬时动力学演化过程或者强场耦合时，必须计入反旋转波项。本项目主要研究纠缠动力学过程中的反旋转波项效应，内容包括：一、反旋转波项对独立的两量子比特纠缠演化产生的效应。二、考虑原子之间的偶极相互作用，研究具有集合原子效应的两量子比特纠缠演化过程中的反旋转波项效应。三、推广到三体及多体系统，研究三体及多体量子比特纠缠动力学演化过程中反旋转波项产生的效应。项目的意义在于，分析反旋转波项和旋转波项在纠缠动力学过程中的相干效应，阐明反旋转波项对纠缠动力学产生效应的物理机制。

本项目的立项目的是研究纠缠动力学过程中的反旋转波项效应。项目的意义在于，系统的了解反旋转波项在纠缠动力学过程中产生的效应，分析反旋转波项和旋转波项在纠缠动力学过程中的相干效应，阐明反旋转波项对纠缠动力学产生效应的物理机制。本课题的研究有助于实现短时标度下有效的纠缠操控和快速的纠缠转移，帮助人们在量子信息处理任务中更深入的了解和利用实际系统在环境影响下的量子纠缠，以实现实际物理体系下量子态的利用和操控。.研究按计划执行。利用腔耗散实现了原子-腔镜的纠缠压缩态，基于原子与光场的四波混频相互作用和腔镜的光辐射压的作用，导致原子与振子以Bogoliubov形式与光场作用，在绝热情况下，腔场使得Bogoliubov模演化到真空态，实现原子和振子的双模纠缠和压缩态；两个远距离薄膜之间的量子态传递。采用光场集合模作为中介来实现量子态传递，分别讨论了以下三种量子态传递方案：两步传递方案，绝热通道方案，混合方案的量子态传递。第一种方案能更强的对抗振子热噪声的影响，而第二种方案能抑制腔场耗散的作用；光力系统中机械耦合的双透明位置依赖。力学作用和辐射压力共同作用激发探测光子进入腔场的三个通道，这三个通道之间的相消干涉导致了探测场的双透明。