论文标题
简单立方晶格中两级原子动力学的量子平均场
Quantum mean-field treatment of the dynamics of a two-level atom in a simple cubic lattice
论文作者
论文摘要
平均场近似用于研究在靠近Curie温度的铁磁晶格中两级原子动力学的一般特征。获得了各种分析和数值结果。我们首先将晶格哈密顿量线性化，并为磁场任意方向的相变阶参数得出了自符势方程。减少的动力学是通过追踪晶格的自由度来推断的，这导致动力学将动力学降低到有效的自旋浴中的原子，该动力学的大小等于晶格的单位单元格的大小。发现通过沿某些特定方向施加磁场，可以提高DEPHASing和激发状态职业概率。还研究了对温度变化和自旋大小的依赖性。事实证明，热波动的增加可能会降低激发态的职业概率。研究了两个这样的原子的纠缠，研究了占据非粘附细胞的纠缠，并发现其时间变化对磁场的方向不太敏感。纠缠猝死和复兴显示出接近临界温度。
The mean field approximation is used to investigate the general features of the dynamics of a two-level atom in a ferromagnetic lattice close to the Curie temperature. Various analytical and numerical results are obtained. We first linearize the lattice Hamiltonian, and we derive the self-consistency equation for the order parameter of the phase transition for arbitrary direction of the magnetic field. The reduced dynamics is deduced by tracing out the degrees of freedom of the lattice, which results in the reduction of the dynamics to that of an atom in an effective spin bath whose size is equal to the size of a unit cell of the lattice. It is found that the dephasing and the excited state occupation probability may be enhanced by applying the magnetic field along some specific directions. The dependence on the change of the temperature and the magnitude of spin is also investigated. It turns out that the increase of thermal fluctuations may reduce the occupation probability of the excited state. The entanglement of two such atoms that occupy non-adjacent cells is studied and its variation in time is found to be not much sensitive to the direction of the magnetic field. Entanglement sudden death and revival is shown to occur close to the critical temperature.
