论文标题
等离子在三维超导体中的分散
Dispersion of plasmons in three-dimensional superconductors
论文作者
论文摘要
我们研究以$ s $波超导状态的均匀三维电子气体的等离子体分支。我们专注于等离子频率$ω_p$与GAP $δ$相媲美的制度，该差距$δ$在丘比特实验中实现。尽管总和保证了等离子体分支的偏离始终与等离子频率一致，但等离子的分散和寿命会受到配对凝结物的存在，尤其是在接近破坏阈值$2δ$的能量的情况下。当$ω_p$高于$1.7δ$时，水平排斥足以使等离子分支具有异常的负分散体，最小值在有限波长下。在非零温度下，在$ω_p>2δ$下，我们以非扰动的方式对待等离子与费米子激发的耦合，并表明在带间隙中，配对破坏连续性的连续均与未障碍的溶液中宽阔的等离子体共振。这种共振分裂与库珀对传播器的分析延续中存在多个极点有关。
We study the plasma branch of an homogeneous three-dimensional electron gas in an $s$-wave superconducting state. We focus on the regime where the plasma frequency $ω_p$ is comparable to the gap $Δ$, which is experimentally realized in cuprates. Although a sum rule guarantees that the departure of the plasma branch always coincides with the plasma frequency, the dispersion and lifetime of the plasmons is strongly affected by the presence of the pair condensate, especially at energies close to the pair-breaking threshold $2Δ$. When $ω_p $ is above $1.7Δ$, the level repulsion is strong enough to give the plasma branch an anomalous, negative dispersion with a minimum at finite wavelength. At non-zero temperature and at $ω_p>2Δ$, we treat in a non-perturbative way the coupling of plasmons to the fermionic excitations, and show that a broadened plasma resonance inside the pair-breaking continuum coexists with an undamped solution in the band gap. This resonance splitting is associated with the presence of multiple poles in the analytic continuation of the propagator of the Cooper pairs.
