Entanglement Degree of Finite-Dimensional Pair Coherent States

We study in detail the entanglement degree of finite-dimensional pair coherent states (PCSs) in terms of different parameters involved in the coherent states. Since these states are a type of correlated two-mode states in finite dimension, we use the D concurrence and linear entropy to quantify their amount of entanglement. We show that the maximum entanglement can be obtained for two and threedimensional (finite-dimensional) PCSs, and states with higher dimensions cannot attain this limit. We generalize the discussion to a superposition of two states of this class and give the maximum entangled states for even and odd finite-dimensional PCSs. In addition, we consider the entanglement degree of nonlinear finite-dimensional PCSs and survey the maximality condition. Finally, we discuss the entanglement for a class of mixed states defined as a statistical mixture of two pure finite-dimensional PCSs. Our observations may have important implications in exploiting these states in quantum information theory.