(a) Momentum-resolved photoemission spectrum, exhibiting an oscillatory behaviour at zero energy reflecting the delocalization of the Majorana states at both ends of the topological superfluid
Figure 7. (a) Momentum-resolved photoemission spectrum, exhibiting an oscillatory behaviour at zero energy reflecting the delocalization of the Majorana states at both ends of the topological superfluid. The small rectangle at zero energy represents the spectrum of the Majorana states shown in (b). (b) Momentum-resolved photoemission spectrum ni(k) for both Majorana states i = 1, 2, differing from the phase of the fast oscillations. The slow modulation (period π/d) reflects the wavefunction modulation by the lattice potential, while the fast oscillation is due to the delocalization of the wavefunction at both ends of the topological superfluid.
We propose an experimental implementation of a topological superfluid with ultracold fermionic atoms. An optical superlattice is used to juxtapose a 1D gas of fermionic atoms and a 2D conventional superfluid of condensed Feshbach molecules. The latter acts as a Cooper pair reservoir and effectively induces a superfluid gap in the 1D system. Combined with a spin-dependent optical lattice along the 1D tube and laser-induced atom tunnelling, we obtain a topological superfluid phase. In the regime of weak couplings to the molecular field and for a uniform gas, the atomic system is equivalent to Kitaev's model of a p-wave superfluid. Using a numerical calculation, we show that the topological superfluidity is robust beyond the perturbative limit and in the presence of a harmonic trap. Finally, we describe how to investigate some physical properties of the Majorana fermions located at the topological superfluid boundaries. In particular, we discuss how to prepare and detect a given Majorana edge state.