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(a) General scheme of the setup, consisting of quasi-1D gases of fermionic atoms coupled to a 2D gas of condensed molecules

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posted on 24.06.2013 by Sylvain Nascimbène

Figure 1. (a) General scheme of the setup, consisting of quasi-1D gases of fermionic atoms coupled to a 2D gas of condensed molecules. The tunnelling of atom pairs into the 1D tubes acts as a superfluid gap applied externally. A spin-dependent optical lattice is applied along the tube, leading to an effective lattice with spin ↑ (↓) particles localized in the even (odd) sites. Atom tunnelling inside the tube is driven by Raman lasers, leading to the realization of Kitaev's model of a p-wave superfluid. (b) Scheme of the atom pair tunnelling from A to B, resonant for Eb = 2 δ.

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.

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