Bell states and entanglement of two-dimensional polar molecules in electric fields

Entanglement generated from polar molecules of two-dimensional rotation is investigated in a static electric field. The electric field modulates the rotational properties of molecules, leading to distinctive entanglement. The concurrence is used to estimate the degree of entanglement. When the electric field is applied parallel or perpendicular to the intermolecular direction, the concurrences reveal two overlapping features. Such a pronounced signature corresponds to the coexistence of all Bell-like states. The characteristics of Bell-like states and overlapping concurrences are kept independent of the modulation of dipole-field and dipole-dipole interactions. On the contrary, the Bell-like states fail to coexist in other field directions, reflecting nonoverlapping concurrences. Furthermore, the thermal effect on the entanglement is analyzed for the Bell-like states. Dissimilar suppressed concurrences occur due to different energy structures for the two specific field directions.