Supervisor: Jan Arlt  

The theory behind crystalline solids and superfluid liquids is well understood individually. A more complicated substance occurs when one tries to combine these two, in what can initially seem like an impossible object. This scenario is known as a supersolid, which behaves simultaneously as a superfluid liquid and crystalline solid.

In this colloquium I will describe supersolids in terms of the known properties of solids and superfluids. An historical account of the initial advancements in the search for a supersolid and the approaches that were used is given. Finally, a modern approach to supersolids is presented in terms of ultracold atoms with focus on recent experiments which have proved to be successful in observing a supersolid state. One of these experiments which makes use of a BEC with light scattering into two optical cavities to obtain supersolid properties, is highlighted.