Structure of two-component Bose-Einstein condensates with respective vortex-antivortex superposition states

摘要

We investigate the phase structure of two-component Bose-Einstein condensates (BECs) with repulsive intraandninterspecies interactions in the presence of respective vortex-antivortex superposition states (VAVSSs). Wenshow that different winding numbers of the vortex and antivortex and different intra- and interspecies interactionnstrengths may lead to different phase configurations, such as fully separated phases, inlaid separated phases,nasymmetric separated phases, and partially mixed phases, where the density profile of each component displaysna petal-like (or modulated petal-like) structure. A phase diagram is given for the case of equal unit windingnnumbers of the vortex and antivortex in the respective components, and it is shown that the conventional criterionnfor phase separation of two-component BECs is not applicable for the present system due to the VAVSSs. Innaddition, our nonlinear stability analysis indicates that the typical phase structures of two-component BECs withnVAVSSs allow them to be detected in experiments. Moreover, for the case of unequal winding numbers of thenvortex and antivortex in the respective components, we find that each component in any of the possible phasenstructures is in a cluster state of vortices and antivortices, where the topological defects appear in the form of ansingly quantized visible vortex, or a hidden vortex, or a ghost vortex, depending on the specific parameters ofnthe system. Finally, a general relationship between the vortex-antivortex cluster state and the winding numbersnof vortex and antivortex is revealed.