Interaction between an impurity and nonlinear excitations in a polariton condensate

Abstract

An important challenge in exploring the dynamics of a mobile impurity immersed in the field excitations comes from the necessity to include the entanglement between the impurity and the surrounding excitations. To address this challenge, the impurity's effective mass has to be assumed as finite, rather than infinite. Here we theoretically investigate how a finite-mass impurity interacts with a nonlinear excitation (i.e., soliton) in the polariton Bose-Einstein condensate (BEC), which is intrinsically non-equilibrium. Using the Lagrange variational method and the open-dissipative Gross-Pitaevskii equation, we analytically derive the interaction phase diagram between a bright soliton and an impurity in a polariton BEC. We show that when the soliton collide with the impurity, it can transmit through, be trapped, or reflected. Our work goes beyond prior researches in the context of equilibrium systems, and opens a new perspective toward understanding the nonequilibrium dynamics of a mobile impurity immersed in the nonliear field excitations.