We study Majorana fermions (MFs) in quasi-one dimensional (quasi-1D) and higher-dimensional fermionic optical lattices with a strictly 1D spin-orbit coupling, which has already been realized in cold atom experiments. We show that when the superfluid order parameters are homogeneous and are enforced to be identical along different chains, there are multiple MFs at each end with or without an experimentally tunable in-plane Zeeman field ${V}_{y}$ . For ${V}_{y}=0$ the multiple MFs are topologically protected by a chiral symmetry; however, for ${V}_{y}\ensuremath{\ne}0$ the existence of multiple MFs is related to the peculiar spectrum properties of the system despite the broken chiral symmetry. In the generalization to higher dimensions, the multiple MFs form a zero-energy flat band. Furthermore, when the superfluid order parameters are solved self-consistently, the multiple MFs are usually destroyed because of the inhomogeneous order parameters of either Bardeen-Cooper-Schrieffer ( ${V}_{y}=0$ ) type or Fulde-Ferrell (${V}_{y}\ensuremath{\ne}0$) type. Our results are useful to guide the experimentalists on searching for MFs in ultracold spin-orbit coupled fermionic superfluids.We study Majorana fermions (MFs) in quasi-one dimensional (quasi-1D) and higher-dimensional fermionic optical lattices with a strictly 1D spin-orbit coupling, which has already been realized in cold atom experiments. We show that when the superfluid order parameters are homogeneous and are enforced to be identical along different chains, there are multiple MFs at each end with or without an experimentally tunable in-plane Zeeman field ${V}_{y}$. For ${V}_{y}=0$ the multiple MFs are topologically protected by a chiral symmetry; however, for ${V}_{y}\ensuremath{\ne}0$ the existence of multiple MFs is related to the peculiar spectrum properties of the system despite the broken chiral symmetry. In the generalization to higher dimensions, the multiple MFs form a zero-energy flat band. Furthermore, when the superfluid order parameters are solved self-consistently, the multiple MFs are usually destroyed because of the inhomogeneous order parameters of either Bardeen-Cooper-Schrieffer (${V}_{y}=0$) type or Fulde-Ferrell (${V}_{y}\ensuremath{\ne}0$) type. Our results are useful to guide the experimentalists on searching for MFs in ultracold spin-orbit coupled fermionic superfluids.

arXiv:1310.7557Physical Review AAug 14, 201512 citations

New phases from interacting Majorana fermions in one dimension

Marcel Franz, Armin Rahmani, Xiaoyu Zhu +1 more

Bulletin of the American Physical SocietyMar 17, 20160 citations

Statistical Certification of Majorana fermions

Abu Ashik Irfan, Karl Mayer, Gerardo Ortíz +1 more

Bulletin of the American Physical SocietyMar 5, 20200 citations

Nonlocal Entanglement of 1D Thermal States Induced by Fermion Exchange Statistics

YeJe Park, Jeongmin Shim, Seung‐Sup B. Lee +1 more

When two identical fermions exchange their positions, their wave function gains a phase factor of -1. We show that this distance-independent effect can induce nonlocal entanglement in one-dimensional (1D) electron systems having Majorana fermions at the ends. It occurs in the system bulk and has a nontrivial temperature dependence. In a system having a single Majorana fermion at each end, the nonlocal entanglement has a Bell-state form at zero temperature and decays as the temperature increases, vanishing suddenly at a certain finite temperature. In a system having two Majorana fermions at each end, it is in a cluster-state form and its nonlocality is more noticeable at a finite temperature. By contrast, the thermal states of corresponding 1D spins do not have nonlocal entanglement.When two identical fermions exchange their positions, their wave function gains a phase factor of -1. We show that this distance-independent effect can induce nonlocal entanglement in one-dimensional (1D) electron systems having Majorana fermions at the ends. It occurs in the system bulk and has a nontrivial temperature dependence. In a system having a single Majorana fermion at each end, the nonlocal entanglement has a Bell-state form at zero temperature and decays as the temperature increases, vanishing suddenly at a certain finite temperature. In a system having two Majorana fermions at each end, it is in a cluster-state form and its nonlocality is more noticeable at a finite temperature. By contrast, the thermal states of corresponding 1D spins do not have nonlocal entanglement.

arXiv:1808.08505Physical Review LettersNov 20, 201711 citations

{V}_{y}

. For

{V}_{y}=0

the multiple MFs are topologically protected by a chiral symmetry; however, for ${V}_{y}\ensuremath{\ne}0$ the existence of multiple MFs is related to the peculiar spectrum properties of the system despite the broken chiral symmetry. In the generalization to higher dimensions, the multiple MFs form a zero-energy flat band. Furthermore, when the superfluid order parameters are solved self-consistently, the multiple MFs are usually destroyed because of the inhomogeneous order parameters of either Bardeen-Cooper-Schrieffer (

{V}_{y}=0

) type or Fulde-Ferrell (${V}_{y}\ensuremath{\ne}0$) type. Our results are useful to guide the experimentalists on searching for MFs in ultracold spin-orbit coupled fermionic superfluids.