Searching for Majorana Fermions in 2D Spin-orbit Coupled Fermi Superfluids at Finite Temperature

摘要

Recent experimental breakthrough in realizing spin-orbit (SO) coupling forcold atoms has spurred considerable interest in the physics of 2D SO coupledFermi superfluids, especially topological Majorana fermions (MFs) which werepredicted to exist at zero temperature. However, it is well known thatlong-range superfluid order is destroyed in 2D by the phase fluctuation atfinite temperature and the relevant physics is theBerezinskii-Kosterlitz-Thouless (BKT) transition. In this Letter, we examinefinite temperature effects on SO coupled Fermi gases and show that finitetemperature is indeed necessary for the observation of MFs. MFs aretopologically protected by a quasiparticle energy gap which is found to be muchlarger than the temperature. The restrictions to the parameter region for theobservation of MFs have been obtained.