论文标题
超导谐振器中的非平衡准粒子分布：分析方法
Nonequilibrium quasiparticle distribution in superconducting resonators: analytical approach
论文作者
论文摘要
在超导状态下，激发光谱中存在有限间隙，这意味着在温度远低于关键的温度下，激发数（准粒子）的数量成倍小。相反，微小的扰动可以显着影响能量分布和准粒子数量。通常，与电磁环境的相互作用是将准粒子从热平衡中驱动的主要扰动源，而声子浴则负责恢复平衡。在这里，我们得出了超导谐振器中准颗粒分布函数的近似分析解，并探索了非平衡对两个可测量量的影响：谐振器的质量因子及其谐振频率。将我们的结果应用于实验数据，我们得出的结论是，在中等温度下，有明确的证据表明，由于光子加热了准粒子而产生的非平衡作用，但低温测量结果并未通过这种机制来解释。
In the superconducting state, the presence of a finite gap in the excitation spectrum implies that the number of excitations (quasiparticles) is exponentially small at temperatures well below the critical one. Conversely, minute perturbations can significantly impact both the distribution in energy and number of quasiparticles. Typically, the interaction with the electromagnetic environment is the main perturbation source driving quasiparticles out of thermal equilibrium, while a phonon bath is responsible for restoration of equilibrium. Here we derive approximate analytical solutions for the quasiparticle distribution function in superconducting resonators and explore the impact of nonequilibrium on two measurable quantities: the resonator's quality factor and its resonant frequency. Applying our results to experimental data, we conclude that while at intermediate temperatures there is clear evidence for the nonequilibrium effects due to heating of the quasiparticles by photons, the low-temperature measurements are not explained by this mechanism.
