(a) Scheme of the bichromatic superlattice potential along z (black line), made of the superposition of two standing waves of wavelength λ (blue line) and 2 λ (red line)

Figure 9. (a) Scheme of the bichromatic superlattice potential along z (black line), made of the superposition of two standing waves of wavelength λ (blue line) and 2 λ (red line). The energy offset δ in the resulting double-well potential can be controlled using a relative offset in position of the two standing waves. (b) Amplitude of the standing wave along z used for generating the y lattice, which vanishes at z_B. (c) Superlattice potential with the Wannier function in plane B centred on z_B.

Abstract

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.