Entanglement Distillation for Mixed States Using Particle Statistics

We extend the idea of entanglement concentration protocol for pure states （Phys. Rev. Lett. 88, 187903） to the case of entanglement distillation for mixed states. The scheme works only with particle statistics and local operations, without the need of any other interactions. We show that the maximally entangled state can be distilled out when the initial state is pure, otherwise the entanglement distilled depends on the off-diagonal element of density matrix of the initial state. Because of the requirement for density matrix, the entanglement distilled is always less than one, and this result is the same for both fermionic and bosonic particles. The distillation efficiency is a product of the diagonal elements of the initial state, it takes the maximum 50%, the same as that in the case for pure states.We extend the idea of entanglement concentration protocol for pure states （Phys. Rev. Lett. 88, 187903） to the case of entanglement distillation for mixed states. The scheme works only with particle statistics and local operations, without the need of any other interactions. We show that the maximally entangled state can be distilled out when the initial state is pure, otherwise the entanglement distilled depends on the off-dlagonal element of density matrix of the initial state. Because of the requirement for density matrix, the entanglement distilled is always less than one, and this result is the same for both fermionic and bosonic particles. The distillation effciency is a product of the diagonal elements of the initial state, it takes the maximum 50%, the same as that in the case for pure states.     

带有Dzyaloshinski-Mariya相互作用的两比特XXZ模型的纠缠量子热机

以带有Dzyaloshinski-Mariya 相互作用的两比特XXZ模型为工作物质构建纠缠量子热机. 在量子热力学平衡态下, 采用Kieu的形式描述了做功与热传递.对于不同的各向异性参数, 分析了热机循环中量子纠缠与热传递、做功以及机械效率等热力学量之间的关系. 结果表明: 在这个纠缠体系中, 热力学第二定律依然成立; 机械效率的等值线图是环状曲线; 当各向异性参数Δ较小时, 热机在C₁ > C₂ 和C₁ < C₂ 两区域运行, 当增大Δ值时, 热机只在C₁ > C₂ 区域运行. 关键词： 量子热机 并发度 机械效率     

Dynamical Evolution and Entanglement in a Nonlinear Interacting System

We investigate a few features of entanglement of two types of particles coupled through a nonlinear interaction. It is shown that the entanglement created by the nonlinear interaction can reflect nonlinearity of the system. Possible observation of our prediction in a double-well trapped Bose-Einstein condensate is discussed.