Stability and internal interaction of multipole solitons in nonlocal PT-symmetric lattices

We investigate the existence, stability and internal interaction of two-dimensional multipole solitons in defocusing PT symmetric nonlocal nonlinear media. Compared with nonlocal fundamental solitons in PT-symmetric lattices, the multipole solitons reveal the novel internal interaction such as the oscillation of the gravity center. We consider the change of the gravity center of dipole solitons during propagation, and find that these dipole solitons have "breather-like" or "competition" behavior in different nonlinearities. We also demonstrate that dipole solitons are easier to be stabilized under the intermediate nonlocality. Moreover, two more complicated multipole solitons are studied and it is found that there also exist the novel internal interaction for the multipole solitons.