Gradient of the Adiabatic Gauge Potential in Classical Systems

Abstract

The adiabatic gauge potential (AGP) is the generator of unitary transformations which preserve the eigenbasis of a quantum Hamiltonian under parametric variation. While its usefulness in quantum mechanics has been thoroughly demonstrated in recent years, less attention has been given to its behavior in classical systems, where the AGP is a phase space function and its gradient defines special canonical transformations. In this paper we propose an efficient method to compute the gradient of the AGP as a classical function. We demonstrate that the obtained canonical transformation reproduces expected results for simple orbits and integrable systems for which the adiabatic limit is well-defined. In chaotic systems the gradient diverges in a way that is related to Lyapunov times.