  The influence of gravitational field on entanglement of bipartite states is
investigated based on the recent idea of superposition states of gravitational
field. Different from earlier considerations, we study the case where the
gravitational field cannot be separated unitarily from the bipartite system in
the final stage of the interaction. When the different gravitational field
states are orthogonal, entanglement cannot be generated for an initial product
state. If the different gravitational field states are non-orthogonal,
entanglement can be generated and the amount of generated entanglement depends
on an overlap parameter between different gravitational field states. The
influence of gravitational field on the transfer of the state through quantum
teleportation is also studied, which might lead to an observable effect since
the quantum teleportation can be performed using macroscopic object.
