Majorana Fermions as Andreev Bound States in Superfluid \(^3\)He-B

In this article in memory of academician A.F. Andreev, we consider the results of experiments in superfluid \(^{3}\) ${}^3$ He-B at ultralow temperatures. These experiments directly demonstrate the existence of gapless Majorana quasiparticles, which appear as Andreev bound states at the boundary of superfluid \(^3\) ${}^3$ He-B (Silaev and Volovik in JETP 119:1042, 2014). Precision measurements of the heat capacity of superfluid \(^3\) ${}^3$ He-B showed that at a temperature of 0.12 mK, Majorana fermions can account for up to \(50\%\) $50\%$ of the heat capacity of \(^3\) ${}^3$ He-B in our experimental conditions.