Spin-twisted Optical Lattices: Tunable Flat Bands and Larkin-Ovchinnikov Superfluids

Abstract

Moiré superlattices in twisted bilayer graphene and transition-metal dichalcogenides have emerged as a powerful tool for engineering novel band structures and quantum phases of two-dimensional quantum materials. Here we investigate Moiré physics emerging from twisting two independent hexagonal optical lattices of atomic (pseudo-)spin states (instead of bilayers), which exhibits remarkably different physics from twisted bilayer graphene. We employ a momentum-space tight-binding calculation that includes all range real-space tunnelings, and show that all twist angles $\theta \lesssim 6^{\circ }$ can become magic that support gapped flat bands. Due to greatly enhanced density of states near the flat bands, the system can be driven to superfluid by weak attractive interaction. Strikingly, the superfluid phase corresponds to a Larkin-Ovchinnikov state with finite momentum pairing, resulting from the interplay between flat bands and inter-spin interactions in the unique single-layer spin-twisted lattice. Our work may pave the way for exploring novel quantum phases and twistronics in cold atomic systems.

4 pages, 4 figures, and Supplementary Materials (7 pages), to appear in Phys. Rev. Lett

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• Synthetic dimensions for topological and quantum phases: Perspective
• Electromagnetically induced moiré optical lattices in a coherent atomic gas
• Magic continuum in twisted bilayer square lattice with staggered flux
• Three-dimensional Moiré Crystal
• State-dependent potentials for the ${}^1{\text{S}}_0$ and ${}^3{\text{P}}_0$ clock states of neutral ytterbium atoms
• Double and Quadruple Flat Bands tuned by Alternative magnetic Fluxes in Twisted Bilayer Graphene
• Quantum phases of dipolar bosons in multilayer optical lattice
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• Interaction induced moiré systems in twisted bilayer optical lattices
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• Vacancy-induced tunable Kondo effect in twisted bilayer graphene
• The low energy excitation spectrum of magic-angle semimetals
• Topologically nontrivial and trivial flat bands via weak and strong interlayer coupling in twisted bilayer honeycomb optical lattices for ultracold atoms
• Tunable symmetry-protected higher-order topological states with fermionic atoms in bilayer optical lattices
• Determining the ${}^3$P${}_0$ excited-state tune-out wavelength of ${}^{174}$Yb in a triple-magic lattice
• Moiré Superradiance in Cavity Quantum Electrodynamics with Quantum Atom Gas
• Electronic properties of twisted multilayer graphene