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AQP Seminar: Engineering of new topological phases of superfluid 3He by controlled correlated disorder.

Aalto Quantum Physics Seminar (Nanotalo). Speaker: Prof. Evgeny Surovtsev (Kapitza Institute, Russia).

Superfluid 3He is an ideal system to examine topological superfluidity and superconductivity. The properties of this extremely pure superfluid system were investigated in details during 45 years since its discovery (phase diagram, excitations, topological defects, spin-supercurrents, BEC of magnons, surface states etc.). In the mid-‘90s new prospects of investigation of this system were found by using aerogels as structures of correlated nano-impurities injected into superfluid 3He.  Such a system exhibits new thermodynamic and topological properties that are not possible in bulk (pure) 3He: new global symmetries, new phases, glass states (Larkin-Imry-Ma state), half-quantum vortices etc. These new properties are dependent on different characteristics of aerogel:  density of aerogel, correlations between elements of aerogel, initial deformation of aerogel, type of surface covering (solid 3He or solid 4He) and so on. The main goal of the talk is to demonstrate what properties of superfluid 3He are affected by aerogel and what are the mechanisms of such influence. Knowledge of such mechanisms is useful for engineering of new superfluid states with predetermined topological properties.