Spin-Depairing-Induced Exceptional Fermionic Superfluidity
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| Format: | Preprint |
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2025
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| _version_ | 1866918263660740608 |
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| author | Takemori, Soma Yamamoto, Kazuki Koga, Akihisa |
| author_facet | Takemori, Soma Yamamoto, Kazuki Koga, Akihisa |
| contents | We investigate the non-Hermitian (NH) attractive Hubbard model with spin depairing, which is a spin-resolved asymmetric hopping that nonreciprocally operates spins in the opposite direction. We find that spin depairing stabilizes a superfluid state unique to the NH system. This phase is characterized not only by a finite order parameter, but also by the emergence of exceptional points (EPs) in the momentum space - a feature that starkly contrasts with previously discussed NH fermionic superfluidity, where EPs are absent within the superfluid state and emerge only at the onset of the superfluid breakdown. We uncover the rich mechanism underlying this ``exceptional fermionic superfluidity'' by analyzing the interplay between EPs and the effective density of states of the complex energy dispersion. Furthermore, we reveal that the exceptional superfluid state breaks down induced by strong spin depairing on the cubic lattice, while it remains robust on the square lattice. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2504_19525 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spin-Depairing-Induced Exceptional Fermionic Superfluidity Takemori, Soma Yamamoto, Kazuki Koga, Akihisa Quantum Gases Statistical Mechanics Strongly Correlated Electrons Superconductivity Quantum Physics We investigate the non-Hermitian (NH) attractive Hubbard model with spin depairing, which is a spin-resolved asymmetric hopping that nonreciprocally operates spins in the opposite direction. We find that spin depairing stabilizes a superfluid state unique to the NH system. This phase is characterized not only by a finite order parameter, but also by the emergence of exceptional points (EPs) in the momentum space - a feature that starkly contrasts with previously discussed NH fermionic superfluidity, where EPs are absent within the superfluid state and emerge only at the onset of the superfluid breakdown. We uncover the rich mechanism underlying this ``exceptional fermionic superfluidity'' by analyzing the interplay between EPs and the effective density of states of the complex energy dispersion. Furthermore, we reveal that the exceptional superfluid state breaks down induced by strong spin depairing on the cubic lattice, while it remains robust on the square lattice. |
| title | Spin-Depairing-Induced Exceptional Fermionic Superfluidity |
| topic | Quantum Gases Statistical Mechanics Strongly Correlated Electrons Superconductivity Quantum Physics |
| url | https://arxiv.org/abs/2504.19525 |