*ITAMP Topical Lunch Discussion* Date: Friday, September 25th Time: 12:00-1:30 pm Pizza will be served. Location: B-106 @ Center for Astrophysics (60 Garden Street) Directions: after entering the lobby of the CfA, turn right to enter the hallway of the B building. In the hallway, turn right again, and B-106 is there. *Speaker*:Márton Kanász-Nagy , Harvard *Title: *Stabilizing the topological vacuum: Mott skyrmions *Abstract: *Topological have kept physicist excited for several decades, mostly due to their beautiful structures and enormous stability. While individual vortices and solitons have been observed in many areas of physics, it is much harder to observe their higher dimensional topological relatives, skyrmions and magnetic monopoles. In particular, earlier attempts to create stable individual skyrmions in ultracold atomic experiments suffered from important instabilities: skyrmions have a tendency to shrink or expand, and to slip away from the atomic trap. In this talk, I will propose that loading a three-component nematic superfluid, such as 23Na, into a deep optical lattice and thereby creating an insulating core, one can create topologically stable individual skyrmions, and investigate their properties in detail. I will show furthermore, that the spectrum of the excitations of the superfluid and their quantum numbers change dramatically in the presence of the skyrmion, and they reflect the presence of a trapped monopole, as imposed by the skyrmion’s topology. -- Stefan Pabst ITAMP Postdoc Alexander von Humboldt Fellow ITAMP, Harvard-Smithsonian Center for Astrophysics 60 Garden Street Cambridge, MA 02138, USA phone: +1-617-495-7239 fax: +1-617-496-7668 email: stefan.pabst(a)cfa.harvard.edu website: www.stefanpabst.name