Topological superfluidity · Topological superfluidity in ultracold gas of Dysprosium atoms

Topological superfluidity in ultracold gas of Dysprosium atoms

"The Nobel Prize in Physics in 2016 has celebrated the efforts of the past decades in understanding the materials with a non-trivial, so-called topological order. In mathematics topology refers to the classification of surfaces depending on properties invariant upon continuous deformations. As an illustration a ball and a torus, having different number of holes, belong to different topological classes. By analogy, topological materials possess some characteristics with an intrinsic stability against local perturbations. These unique properties might be used to dramatically decrease the coupling of the quantum system with a ""noisy"" environment, with possible application in a new generation of metrology standards and inherently error-free quantum computation. Recently, the concept of topological matter was successfully generalized to superconductors, opening new exciting research directions. In our project, we experimentally investigate the phenomenon of superfluidity, that shares similar physics with supercondustivity, with the difference of supercurrents being formed by neutral particles (atoms) instead of paired electrons. Topological properties of the superfluid are directly connected with the type of pairing between the particles. Trivial topology, corresponding to the pairing between two fermionic particles with different internal states (for example, opposite spin directions for electrons), was experimentally realized in different systems and described within Bardeen-Cooper-Schrieffer theory. A topologically non-trivial superfluid state is more experimentally challenging and requires effective simulation of the pairing between fermionic atoms with identical spin via carefully engineered coupling between their spin and motional degrees of freedom, so-called spin-orbit coupling (SOC). By means of atom-light interaction in our experiment we aimed to create an artificial SOC and study its key role in topological properties of materials. The main objectives of our project were to understand the underlying mechanisms of SOC and realize a topological superfluid with ensembles of Dysprosium atom at ultra-low temperatures. We have developed and implemented the necessary toolbox for studying topological superfluid state. We performed preliminary experiments which were necessary to fine-tune our apparatus and answer related open questions in our field. These results constitute a benchmark for the experimental study of ultracold gases of magnetic Lanthanide atoms. The atom-light interactions and SOC mechanisms in our system is currently under active experimental investigation. The results will be presented most likely before the end of the year 2017."

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