Dark solitons in nonlinear media with arbitrary degree of nonlocality

Here we describe analytically, for the first time to our knowledge, properties of dark nonlocal solitons. To this end we employ a variational approach and show that it enables one to retrieve the major features of dark solitons in a general nonlocal regime. And we also investigate analytically the interaction of dark solitons in nonlocal media with an arbitrary degree of nonlocality. Our results clearly show how nonlocality induces an attractive force, which depends on the degree of nonlocality and counteracts the otherwise inherent repulsive nature of dark soliton interaction.