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arXiv · 2505.01010

Quasi-local Frustration-Free Free Fermions

Shunsuke Sengoku·Hoi Chun Po·Haruki Watanabe
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Abstract

Recent studies have revealed that frustration-free models, expressed as sums of finite-range interactions or hoppings, exhibit several properties markedly different from those of frustrated models. In this work, we demonstrate that, by relaxing the finite-range condition to allow for exponentially decaying hoppings, one can build gapped frustration-free systems that realize Chern insulators as well as quasi-degenerate ground states with finite-size splittings. Moreover, by permitting power-law decaying hoppings, we also construct a gapless band metal whose finite-size gap scales inversely with the system size $L$. These findings serve as an important step toward clarifying the general properties of frustration-free systems and those represented by tensor network states.

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Shunsuke Sengoku, Hoi Chun Po, Haruki Watanabe. 2025-05-02. Quasi-local Frustration-Free Free Fermions. https://doi.org/10.1103/794x-jdn7

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