Maximal Entanglement of Two-Qubit States Constructed by Linearly Independent Coherent States

In this paper, we find the necessary and sufficient condition for the maximal entanglement of the state, |ψ〉=μ|α〉|β〉+λ|α〉|δ〉+ρ|γ〉|β〉+ν|γ〉|δ〉, constructed by linearly independent coherent states with real parameters when 〈α|γ〉=〈β|δ〉. This is a further generalization of the classified nonorthogonal states discussed in Fu et al. (Phys. Lett. A 291:73–76, 2001).