一维费米气体中具有共存$s$-波和$p$-波相互作用的有限动量三聚体与库珀四聚体
Finite-momentum trimers and Cooper quartets in a one-dimensional Fermi gas with coexistent $s$- and $p$-wave interactions
- RIKEN Nishina Center for Accelerator-Based Science（理化学研究所仁科加速器科学中心）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究在一维费米气体中研究有限动量三聚体与库珀四聚体，发现四聚体束缚由多体效应决定，而非单对或主导相互作用能，且费米海增强弱耦合四聚体束缚。
AI中文摘要：
我们研究了一维双组分费米气体中具有共存$s$-波和$p$-波相互作用的有限动量三聚体与库珀四聚体，该相互作用在每对粒子的相对动量下进行正则化，以保持伽利略不变性。仅泡利阻塞就使三聚体的色散偏离自由质心运动，因此三聚体能量可在有限总动量处达到最低。允许这种运动扩展了$abb$区域（在成对态与三聚体之间），并消除了奇波对能量最低的区域。在所有采样的耦合强度下，$aabb$四聚体都低于所有这些分支，并且在从两个二聚体-对通道交叉处起始的一条带状区域内，其最低碎裂通道是一个运动的$abb$三聚体加一个原子。在弱种间吸引下，一个变分界表明两个奇波库珀对束缚成一个四聚体，随着吸引减弱，其束缚能比共存的三聚体高出数个数量级。在较强种间吸引下，当奇波相互作用被关闭时，四聚体相对于两个异种二聚体的束缚能消失，尽管偶波相互作用主导了相互作用能。相对于真空情形，费米海增强了弱耦合四聚体的束缚能，并且在固定散射长度下，四聚体束缚能随密度增加而增大，而共存的三聚体则变得浅得多。这些结果表明，既不是最强束缚对，也不是主导的相互作用能单独决定四聚体是否束缚。
英文摘要：
We study finite-momentum trimers and Cooper quartets in a one-dimensional two-component Fermi gas with coexistent $s$- and $p$-wave interactions, regularized in the relative momentum of each pair so that they remain Galilean invariant. Pauli blocking alone then makes the trimer dispersion deviate from free center-of-mass motion, so the trimer energy can be lowest at finite total momentum. Allowing this motion expands the $abb$ region among pairs and trimers and removes the region where an odd-wave pair is lowest. The $aabb$ quartet lies below all these branches at every sampled coupling, and in a strip starting on the crossing of the two dimer-pair channels its lowest breakup channel is a moving $abb$ trimer and an atom. At weak interspecies attraction, a variational bound shows that two odd-wave Cooper pairs bind into a quartet, whose binding exceeds that of the coexisting trimer by orders of magnitude as the attraction weakens. At stronger interspecies attraction, the quartet binding relative to two unlike-species dimers disappears when the odd-wave interaction is switched off, although the even-wave interaction dominates the interaction energy. Relative to the in-vacuum case, the Fermi sea enhances the weak-coupling quartet binding, and at fixed scattering lengths the quartet binding grows with density while the coexisting trimer becomes much shallower. These results show that neither the most strongly bound pair nor the dominant interaction energy alone determines whether the quartet binds.
