论文标题
旋转中的超导性增强 - $ \ frac {1} {2} $ fermion链，耦合到$ \ mathbb {z} _2 $ lattice Gauge字段
Confinement-Induced Enhancement of Superconductivity in a Spin-$\frac{1}{2}$ Fermion Chain Coupled to a $\mathbb{Z}_2$ Lattice Gauge Field
论文作者
论文摘要
我们研究了一个旋转 - $ \ frac {1} {2} $ fermion链，最小化与$ \ mathbb {z} _2 $ gauge字段。在量规生成器$ \ hat g_j = -1 $的扇区中，该模型以排斥的现场交互将耦合到$ \ Mathbb {z} _2 $ gauge字段的替补式现场交互。我们发现电场如何通过分析方法和数值方法影响低能量激发。在半填充情况下，尽管电场，该系统仍然是莫特绝缘子，就像哈伯德模型一样。对于孔掺杂的系统，孔限制在非零电场下，导致孔对结合状态。此外，这种约束状态也显着影响超导性，这表现出了自身在邦德单线库珀对之间有吸引力的相互作用的出现。具体而言，数值结果表明，在增加电场时，主要超导顺序参数的尺寸变小了，这表明了晶格费米恩限制引起的超导不稳定的增强。超导顺序甚至可以成为适当掺杂和大型施加电场的系统的主要顺序。该限制还引起了$π$动量的主导超导顺序参数，从而导致准长范围对密度波顺序。我们的结果为理解$ \ Mathbb {Z} _2 $ LGTS中非常规超导的见解提供了见解，并可能在量子模拟器中实验解决。
We investigate a spin-$\frac{1}{2}$ fermion chain minimally coupled to a $\mathbb{Z}_2$ gauge field. In the sector of the gauge generator $\hat G_j =-1$, the model reduces to the Hubbard model with repulsive onsite interaction coupled to a $\mathbb{Z}_2$ gauge field. We uncover how electric fields affect low-energy excitations by both analytical and numerical methods. In the half-filling case, despite electric fields, the system is still a Mott insulator, just like the Hubbard model. For hole-doped systems, holes are confined under nonzero electric fields, resulting in a hole-pair bound state. Furthermore, this bound state also significantly affects the superconductivity, which manifests itself in the emergence of attractive interactions between bond singlet Cooper pairs. Specifically, numerical results reveal that the dimension of the dominant superconducting order parameter becomes smaller when increasing the electric field, signaling an enhancement of the superconducting instability induced by lattice fermion confinement. The superconducting order can even be the dominant order of the system for suitable doping and large applied electric field. The confinement also induces a $π$ momentum for the dominant superconducting order parameter leading to a quasi-long-range pair density wave order. Our results provide insights for understanding unconventional superconductivity in $\mathbb{Z}_2$ LGTs and might be experimentally addressed in quantum simulators.
