Two-mode excited entangled coherent states and their entanglement properties

We introduce two types of two-mode excited entangled coherent states (TMEECSs) $|\Psi_{\pm}(\alpha,m,n)>$, study their entanglement characteristics, and investigate the influence of photon excitations on quantum entanglement. It is shown that for the state $|\Psi_{+}(\alpha,m,n)>$ the two-mode photon excitations affect seriously entanglement character while the the state $|\Psi_{-}(\alpha,m,n)>$ is always a maximally entangled state. We show how such states can be produced by using cavity QED and quantum measurements. It is found that the entanglement amount of the TMEECSs is larger than that of the single-mode excited entangled coherent states with the same photon excitation number.