Effective Hamiltonian with tunable mixed pairing in driven optical lattices

Abstract

Mixed pairing in ultracold Fermi gases can give rise to interesting many-body phases, such as topological nontrivial superfluids that support Majorana zero modes (MZMs) with various spatial configurations. Unfortunately, in ordinary lattice systems, the topological phase and the associated MZMs are suppressed by the dominant s-wave pairing. Here we present a proposal for engineering effective Hamiltonians with tunable mixed on-and off-site pairing based on driven optical lattices. The on-and off-site pairing can be changed independently by means of a periodical driving field rather than magnetic Feshbach resonances. It paves the way for suppressing the dominant onsite interaction that frustrates the emergence of topological superfluids and for synthesizing MZMs localized in edges or corners.

Bogoliubov corner excitations in a conventional s-wave superfluid

“…Topological superconductors and superfluids as one type of nontrivial topological states have attracted great attention due to nontrivial non-Abelian Majorana modes and potential applications in topological quantum computing. In recent years, higher-order topological superconductors and superfluids are proposed in various platforms, such as superconductor-topological insulator heterostructures [13][14][15][16][17][18][19][20][21][22], iron-based superconductors [23][24][25][26][27][28], π-Joesphson junctions [29,30], ultracold atomic systems [31][32][33][34][35][36][37][38] and (twisted) bilayer graphene [39,40]. Majorana (Kramers) corner or hinge modes naturally arise as the exhibitions of nontrivial higher-order topology.…”