Dirac Monopoles in a Bose-Einstein Condensate

Michael Ray, Emmi Ruokokoski, Saugat Kandel +2 more

Michael Ray, Emmi Ruokokoski, Konstantin Tiurev +2 more

Azure Hansen, Justin T. Schultz, N. P. Bigelow

Ville Pietilä, Mikko Möttönen

We demonstrate theoretically that, by using external magnetic fields, one can imprint pointlike topological defects on the spin texture of a dilute Bose-Einstein condensate. The symmetries of the condensate order parameter render this topological defect to be accompanied with a vortex filament corresponding to the Dirac string of a magnetic monopole. The vorticity in the condensate coincides with the magnetic field of a magnetic monopole, providing an ideal analogue to the monopole studied by Dirac.

Ji Li, Yanmei Yu, Lin Zhuang +1 more

We report Dirac monopoles with a polar-core vortex induced by spin-orbit coupling in ferromagnetic Bose-Einstein condensates, which are attached to two nodal vortex lines along the vertical axis. These monopoles are more stable in the time scale of experiment and can be detected through directly imaging vortex lines. When the strength of spin-orbit coupling increases, Dirac monopoles with a vortex can be transformed into those with a square lattice. In the presence of spin-orbit coupling, increasing the strength of the interaction can induce a cyclic phase transition from Dirac monopoles with a polar-core vortex to those with a Mermin-Ho vortex. The spin-orbit coupled Bose-Einstein condensates not only provide a unique platform for investigating exotic monopoles and relevant phase transitions but also can hold stable monopoles even though a quadrupole field is turned off.

Luis J. Garay