Majorana Fermions : Direct Measurements in superfluid 3He

Orateur : Yury BUNKOV

The Majorana fermions, which acts as its own antiparticle, was suggested by Majorana in 1937. While no stable particle with Majorana properties has not yet been o bserved, Majorana quasiparticles (QPs) was suggested at the boundaries of topological insulators, like superfluid 3He-B. Here we report the direct observation of Majorana QPs by precise measurements of the superfluid 3He-B heat capacity. We have succeed to separate the temperature dependence of the bulk Bogolyubov fermions and the surface Majorana fermions heat capacity. The Bogolyubov QPs in bulk 3He-B have a gap and consequently its heat capacity drops down exponentially with cooling. The Majorana QPs behave as a two dimensional gas on the surface of the cell with 3He-B. Majorana QPs have a zero gap, but they have a kinetic energy. Owing to this energy the Majorana QPs have a heat capacity, which drops down with cooling by power law. In our experiments we have found the deviation of exponential law of Bogolyubov QPs heat capacity, which corresponds well to an additional heat capacity due to zero gaped Majorana particles. The very good agreement with a theoretical prediction sup ports our claim of a direct observation of zero gaped Majorana particles.

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