**2. Topological properties of superfluids and superconductors**

Recently, there has been a growing interest in both fields for the important implications of the two phenomena in terms of their topological properties. In particular, if stirred, superfluids form cellular vortices that rotate indefinitely. On the other hand, also multiply-connected superconductors form vortices giving rise to flux quantization that can be just like the quantization of

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

circulation in multiply-connected superfluids. Quantized vortex structures are characterized by a singularity in the center and the vortex core is quantified by means of vorticity, a topological charge otherwise called winding number characterizing the strength of a vortex and identifying superfluid and superconducting vortices as topological defects. This description is an important step forward in both fields because the study of the topological properties is crucial to fully understand the underlying physics in the systems exhibiting either superconductivity or superfluidity.

**Section 2**

**Superfluidity: Theory and Observation**
