超导体中Higgs模的玻色-爱因斯坦凝聚界限
Bounds on Bose-Einstein Condensation of Higgs modes in a Superconductor
- University of Basel（巴塞尔大学）
- King Fahd University of Petroleum and Minerals（法赫德国王石油矿物大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究从BCS哈密顿量推导出耦合Higgs-Goldstone-电子系统的微观理论，确定了光泵浦Higgs模发生玻色-爱因斯坦凝聚的密度窗口，并证明在现实材料参数下可实现该非平衡凝聚。
AI中文摘要：
超导体中的集体模对应于序参量振幅（Higgs模）或相位（Goldstone模）的涨落。从BCS哈密顿量出发，我们推导出一个包含这些自由度之间所有相互作用的耦合Higgs-Goldstone-电子系统的微观哈密顿量。Higgs子系统是一个弱相互作用的玻色气体：Higgs模通过Bogoliubov准粒子对的虚交换感受到相互吸引。它们还与外部电磁场相互作用，我们显式地推导出其耦合常数。我们利用这一理论来研究光泵浦的Higgs模气体是否能够发生玻色-爱因斯坦凝聚。我们确定了一个密度窗口，其下界由平衡凝聚判据决定，上界由吸引相互作用导致的坍缩决定，在该窗口内凝聚可以发生，并且我们推导了由外部泵浦产生的Higgs模的预期密度。这种泵浦关键依赖于费米能量附近电子色散的非抛物型修正。我们证明，对于现实材料参数，泵浦模密度与凝聚是相容的。我们提出了这种非平衡凝聚的可能实验特征。
英文摘要：
Collective modes in a superconductor correspond to fluctuations in the amplitude (Higgs mode) or the phase (Goldstone mode) of the order parameter. Starting from the BCS Hamiltonian, we derive a microscopic Hamiltonian for the coupled Higgs-Goldstone-electron system that contains all interactions among these degrees of freedom. The Higgs subsystem is a weakly interacting Bose gas: Higgs modes experience a mutual attraction mediated by the virtual exchange of Bogoliubov quasi-particle pairs. They also interact with external electromagnetic-fields with a coupling constant that we derive explicitly. We use this theory to examine whether an optically pumped gas of Higgs modes can undergo Bose-Einstein condensation. We identify a density window, bounded below by the equilibrium condensation criterion and above by collapse due to the attractive interaction, in which condensation can occur and we derive the expected density of Higgs-modes due to external pumping. This pumping depends crucially on non-parabolic corrections to the electron dispersion around the Fermi-energy. We show that the pumped mode density is compatible with condensation for realistic material parameters. We suggest possible experimental signatures of this non-equilibrium condensate.
