Attractive interaction between spinless fermions in a two-dimensional lattice drives the formation of a topological superfluid. But the topological phase is dynamically unstable towards phase separation when the system has a high density of states and large interaction strength. This limits the critical temperature to an experimentally challenging regime where, for example, even ultracold atoms and molecules in optical lattices would struggle to realize the topological superfluid. We propose that the introduction of a weaker longer-range repulsion, in addition to the short-range attraction between lattice fermions, will suppress the phase separation instability. Taking the honeycomb lattice as an example, we use the unrestricted Hartree-Fock approximation to show that our proposal significantly enlarges the stable portion of the topological superfluid phase and increases the critical temperature by an order of magnitude. Our work opens a route to enhance the stability of topological superfluids by engineering interparticle interactions.

中文翻译：

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稳定晶格费米子的拓扑超流性

二维晶格中无自旋费米子之间的吸引力相互作用驱动了拓扑超流体的形成。但是当系统具有高状态密度和大相互作用强度时，拓扑相对于相分离是动态不稳定的。这将临界温度限制在具有实验挑战性的范围内，例如，即使是光学晶格中的超冷原子和分子也难以实现拓扑超流体。我们提出，除了晶格费米子之间的短程吸引力之外，引入较弱的长程排斥将抑制相分离的不稳定性。以蜂窝格子为例，我们使用不受限制的 Hartree-Fock 近似来表明我们的提议显着扩大了拓扑超流体相的稳定部分，并将临界温度提高了一个数量级。我们的工作开辟了一条通过设计粒子间相互作用来增强拓扑超流体稳定性的途径。