Maxon and roton solitons in a Rydberg-dressed Bose-Einstein condensate

We present a scheme to generate maxon and roton solitons via the maxon and roton excitations of a Rydberg-dressed Bose-Einstein condensate (BEC). We show that the strong, long-range Rydberg-Rydberg interaction between Rydberg atoms can drastically alter the linear excitation spectrum of the quasiparticles (phonons) on the homogeneous background of the BEC, which displays obvious maxon-roton character and can be tuned actively by adjusting the strength of the Rydberg-Rydberg interaction and Rydberg blockade radius. We also show that the system supports both bright maxon and dark roton solitons if the center wave numbers of excited wave packets are chosen respectively to be those of the maxon and roton. Moreover, we corroborate that both the maxon and roton solitons are dynamical stable during the evolution if system parameters are kept in the domain where the homogeneous background of the BEC is modulationally stable. The results reported are beneficial not only for understanding the physical property of Rydberg-dressed BECs, but also for creating and actively manipulating new types of nonlinear matter-wave excitations in cold atomic gases.