标题： 有限温度下纠缠偏度的数值重整化群方法 显示英文标题

标题： Numerical renormalization group method for entanglement negativity at finite temperature

摘要： 我们开发了一种数值方法，以计算杂质与浴在有限温度下量子杂质系统中的纠缠度量——非正性。 我们通过使用数值重整化群（NRG）构造了一个热密度矩阵，并通过实现一种将计算成本指数级降低的NRG近似方法来评估非正性。 我们将该方法应用于单杂质库隆模型和单杂质安德森模型。 在库隆模型中，当温度远低于库隆温度时，非正性表现出幂律标度，而在高温下则出现突然死亡。 在安德森模型中，当杂质的局域库仑排斥有限时，即使在零温度下，杂质的电荷涨落也会对非正性产生贡献；而在低温下，杂质自旋与浴之间的非正性表现出与库隆模型相同的幂律标度行为。 显示英文摘要

摘要： We develop a numerical method to compute the negativity, an entanglement measure for mixed states, between the impurity and the bath in quantum impurity systems at finite temperature. We construct a thermal density matrix by using the numerical renormalization group (NRG), and evaluate the negativity by implementing the NRG approximation that reduces computational cost exponentially. We apply the method to the single-impurity Kondo model and the single-impurity Anderson model. In the Kondo model, the negativity exhibits a power-law scaling at temperature much lower than the Kondo temperature and a sudden death at high temperature. In the Anderson model, the charge fluctuation of the impurity contribute to the negativity even at zero temperature when the on-site Coulomb repulsion of the impurity is finite, while at low temperature the negativity between the impurity spin and the bath exhibits the same power-law scaling behavior as in the Kondo model.