Core filling of dark solitons in a topological superfluid with one-dimensional spin-orbit coupling

We investigated the core-filling properties of dark solitons in one-dimensional spin-orbit-coupled Fermi gases. Majorana fermions can exist at the edges of the topological superfluid, when the spin-orbit coupling drives this system from the superfluid to the topological superfluid. Our results show that when dark solitons participate, the state of the system and the existence of Majorana zero-energy modes at the edges of topological superfluid correlate with the filling status of the core of the dark soliton. Furthermore, this dark soliton can actually accommodate two extra Majorana excitations without interactions in its core, when it is filled with highly imbalanced spins in a specific region of parameters. These features can be utilized to manipulate Majorana fermions in the topological superfluid.