标题： 2+1D临界费米面的涨落谱及其在光学电导率和流体力学中的应用 显示英文标题

标题： Fluctuation Spectrum of 2+1D Critical Fermi Surface and its Application to Optical Conductivity and Hydrodynamics

摘要： 我们扩展了在配套论文[H.Guo,arXiv:2311.03455]中开发的动力学算子形式，以研究涨落正常模式的一般本征值。我们将该形式应用于计算接近伊辛-向列量子临界点的临界费米面的光学电导率。我们发现电导率是多个传导通道的总和，包括动力学算子的软和非软本征向量，因此使用适用于动量守恒系统的扩展德鲁德公式来解释光学电导率是不合适的。我们还表明，FS软模的传播由一个玻尔兹曼方程控制，从该方程中可以出现流体力学。我们计算了粘度，其显示出非费米液体物理的明显特征。 显示英文摘要

摘要： We extend the kinetic operator formalism developed in the companion paper [H.Guo,arXiv:2311.03455] to study the general eigenvalues of the fluctuation normal modes. We apply the formalism to calculate the optical conductivity of a critical Fermi surface near the Ising-Nematic quantum critical point. We find that the conductivity is the sum of multiple conduction channels including both the soft and non-soft eigenvectors of the kinetic operator, and therefore it is not appropriate to interpret the optical conductivity using extended Drude formula for momentum conserved systems. We also show that the propagation of the FS soft modes is governed by a Boltzmann equation from which hydrodynamics emerges. We calculate the viscosity and it shows clear signature of the non-Fermi liquid physics.