Separability Conditions for a Subclass of Circulant States in Two-Qutrit System and Quasi-Distillation of Entanglement

We will show the necessary and sufficient condition of separability for a sub-class of circulant states in the ℂ3 ⊗ ℂ3 system. This sub-class includes the models proposed by several authors as special cases. Moreover, it will be proved that our separability condition equals to the failure condition of quasi-distillation of entanglement.