Length--Velocity Gauge Equivalence of Quantum Geometric Nonlinear Conductivity in the Adiabatic DC Limit
The episode discusses a paper establishing gauge-consistent density-matrix theory for intrinsic nonlinear conductivity in both length and velocity gauges. This confirms that the adiabatic DC response is determined by a Fermi surface quantum geometric contribution linked to the quantum metric tensor. The hosts conclude that this provides a robust framework for predicting the reactive part of the nonlinear Hall response, while noting future work must focus on incorporating realistic impurity scattering for dissipative components.