In this paper we study an interacting mixture of ultracold spinless fermions on the $s$ band and bosons on the $p$ band in a 2D square optical lattice, of which the effective model is reduced to a $p$ -band fermionic system with nearest-neighbor attractive interaction. From this effective $p$ -band model, we find a translation symmetry protected ${\mathbb{Z}}_{2}$ topological superfluid that is characterized by a special fermion parity pattern at high-symmetry points in momentum space $\mathbf{k}=(0,0)$ , $(0,\ensuremath{\pi})$, $(\ensuremath{\pi},0)$, $(\ensuremath{\pi},\ensuremath{\pi})$. Such ${\mathbb{Z}}_{2}$ topological superfluid supports the robust Majorana edge modes and a new type of low-energy excitation---(supersymmetric) ${\mathbb{Z}}_{2}$ link excitation.In this paper we study an interacting mixture of ultracold spinless fermions on the $s$ band and bosons on the $p$ band in a 2D square optical lattice, of which the effective model is reduced to a $p$-band fermionic system with nearest-neighbor attractive interaction. From this effective $p$-band model, we find a translation symmetry protected ${\mathbb{Z}}_{2}$ topological superfluid that is characterized by a special fermion parity pattern at high-symmetry points in momentum space $\mathbf{k}=(0,0)$, $(0,\ensuremath{\pi})$, $(\ensuremath{\pi},0)$, $(\ensuremath{\pi},\ensuremath{\pi})$. Such ${\mathbb{Z}}_{2}$ topological superfluid supports the robust Majorana edge modes and a new type of low-energy excitation---(supersymmetric) ${\mathbb{Z}}_{2}$ link excitation.

Physical Review BAug 20, 201211 citations

Cavity-Mediated Unconventional Pairing in Ultracold Fermionic Atoms

Frank Schlawin, Dieter Jaksch

We investigate long-range pairing interactions between ultracold fermionic atoms confined in an optical lattice which are mediated by the coupling to a cavity. In the absence of other perturbations, we find three degenerate pairing symmetries for a two-dimensional square lattice. By tuning a weak local atomic interaction via a Feshbach resonance or by tuning a weak magnetic field, the superfluid system can be driven from a topologically trivial s wave to topologically ordered, chiral superfluids containing Majorana edge states. Our work points out a novel path towards the creation of exotic superfluid states by exploiting the competition between long-range and short-range interactions.We investigate long-range pairing interactions between ultracold fermionic atoms confined in an optical lattice which are mediated by the coupling to a cavity. In the absence of other perturbations, we find three degenerate pairing symmetries for a two-dimensional square lattice. By tuning a weak local atomic interaction via a Feshbach resonance or by tuning a weak magnetic field, the superfluid system can be driven from a topologically trivial s wave to topologically ordered, chiral superfluids containing Majorana edge states. Our work points out a novel path towards the creation of exotic superfluid states by exploiting the competition between long-range and short-range interactions.

arXiv:1906.10035Physical Review LettersSep 24, 201941 citations

Superfluid properties of ultracold fermionic atoms in two-dimensional optical lattices

Masahisa Koga, Akihisa Koga

Jan 1, 20100 citations

Topological superfluid in a fermionic bilayer optical lattice

Ya-Jie Wu, Jing He, Chun-Li Zang +1 more

arXiv:1209.5463The European Physical Journal BMar 1, 20132 citations

Majorana fermions in quasi-1D and higher dimensional ultracold optical lattices

Chunlei Qu, Ming Gong, Yong Xu +2 more

We show that Majorana fermions (MFs) exist in twoand three-dimensional (2D,3D) fermionic optical lattices with strictly 1D spin-orbit coupling (SOC) which has already been realized in experiments. For a quasi-1D topological BCS superfluid, there are multiple MFs at each end which are topologically protected by a chiral symmetry. In the generalization to higher dimensions, the multiple MFs form a zero energy flat band. An additional experimentally tunable in-plane Zeeman field drives the system to a topological Fulde-Ferrell (FF) superfluid phase. We find that even though the multiple MFs are robust against the in-plane Zeeman field if the order parameters at the different chains are enforced to be identical, they are destroyed in the self-consistently obtained FF phase where the order parameters are inhomogeneous on the boundaries. Our results are useful to guide the experimentalists on searching for MFs in the context of ultracold fermionic atoms.We show that Majorana fermions (MFs) exist in twoand three-dimensional (2D,3D) fermionic optical lattices with strictly 1D spin-orbit coupling (SOC) which has already been realized in experiments. For a quasi-1D topological BCS superfluid, there are multiple MFs at each end which are topologically protected by a chiral symmetry. In the generalization to higher dimensions, the multiple MFs form a zero energy flat band. An additional experimentally tunable in-plane Zeeman field drives the system to a topological Fulde-Ferrell (FF) superfluid phase. We find that even though the multiple MFs are robust against the in-plane Zeeman field if the order parameters at the different chains are enforced to be identical, they are destroyed in the self-consistently obtained FF phase where the order parameters are inhomogeneous on the boundaries. Our results are useful to guide the experimentalists on searching for MFs in the context of ultracold fermionic atoms.

Bulletin of the American Physical SocietyJun 6, 20140 citations

In this paper we study an interacting mixture of ultracold spinless fermions on the

s

band and bosons on the

p

band in a 2D square optical lattice, of which the effective model is reduced to a

p

-band fermionic system with nearest-neighbor attractive interaction. From this effective

p

-band model, we find a translation symmetry protected

{\mathbb{Z}}_{2}

topological superfluid that is characterized by a special fermion parity pattern at high-symmetry points in momentum space

\mathbf{k}=(0,0)

, $(0,\ensuremath{\pi})$, $(\ensuremath{\pi},0)$, $(\ensuremath{\pi},\ensuremath{\pi})$. Such

{\mathbb{Z}}_{2}

topological superfluid supports the robust Majorana edge modes and a new type of low-energy excitation---(supersymmetric)

{\mathbb{Z}}_{2}

link excitation.