Controlling quantum coherence of a two-component Bose–Einstein condensate via an impurity atom

We propose a scheme to control quantum coherence of a two-component Bose–Einstein condensate (BEC) by a single impurity atom immersed in the BEC. We show that the single impurity atom can act as a single-atom valve (SAV) to control quantum coherence of the two-component BEC. It is demonstrated that the SAV can realize the on-demand control over quantum coherence at an arbitrary time. Specially, it is found that the SAV can also control higher-order quantum coherence of two-component BEC. We investigate the long-time evolution of quantum coherence of the two-component BEC and find that collapse–revival patterns of quantum coherence can be manipulated by the initial-state parameters of the impurity atom and the impurity–BEC interaction strengths.