Stabilizing the False Vacuum: Mott Skyrmions

January 16, 2015
Figure 2: Inner structure of the skyrmion in the (x, z) plane

Figure 2: Inner structure of the skyrmion in the (x, z) plane. (a) In-trap SF densities of the |+1〉 (|−1〉) bosons form a vortex (antivortex) around the equator, whereas that of the |0〉 condensate in (b) creates a dark soliton at the poles. [from M. Kanász-Nagy, B. Dóra, E.A. Demler & G. Zaránd, "Stabilizing the false vacuum: Mott skyrmions," Scientific Reports 5:7692 | doi:10.1038/srep07692. Reprinted by permission from Macmillan Publishers Ltd: Scientific Reports ©2015.

Topological excitations keep fascinating physicists since many decades. While individual vortices and solitons emerge and have been observed in many areas of physics, their most intriguing higher dimensional topological relatives, skyrmions (smooth, topologically stable textures) and magnetic monopoles emerging almost necessarily in any grand unified theory and responsible for charge quantization remained mostly elusive. Researchers from Budapest University of Technology and Economics and from Harvard, including Prof. Eugene Demler and the Fellow of the Harvard Department of Physics Kanász-Nagy, propose that, by 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 skyrmion textures. The skyrmion's extreme stability and compact geometry enable one to investigate its structure and the interplay of topology and excitations in detail. In particular, the superfluid's excitation spectrum as well as the quantum numbers are demonstrated to change dramatically due to the skyrmion, and reflect the presence of a trapped monopole, as imposed by the skyrmion's topology. The study was published in Scientific Reports on January 13, 2015.