Absence of Weak Localization on Negative Curvature Surfaces

TL;DR

This paper demonstrates that negative curvature surfaces can suppress weak localization effects, leading to classical diffusion behavior even in disordered quantum systems, by providing a geometric mechanism that disrupts quantum interference.

Contribution

It introduces a novel geometric approach showing how negative curvature can prevent localization, supported by explicit calculations of the Cooperon in hyperbolic space.

Findings

Negative curvature introduces an infrared cutoff for return paths.

Hyperbolic space enhances the number of trajectories, reducing interference.

Classical diffusion is restored despite disorder.

Abstract

The interplay between disorder and quantum interference leads to a wide variety of physical phenomena including celebrated Anderson localization -- the complete absence of diffusive transport due to quantum interference between different particle trajectories. In two dimensions, any amount of disorder is thought to induce localization of all states at long enough length scales, though this may be prevented if bands are topological or have strong spin-orbit coupling. In this note, we present a simple argument providing another mechanism for disrupting localization: by tuning the underlying curvature of the manifold on which diffusion takes place. We show that negative curvature manifolds contain a natural infrared cut off for the probability of self returning paths. We provide explicit calculations of the Cooperon -- directly related to the weak-localization corrections to the conductivity -- in hyperbolic space. It is shown that constant negative curvature leads to a rapid growth in the number of available trajectories a particle can coherently traverse in a given time, reducing the importance of interference effects and restoring classical diffusive behavior even in the absence of inelastic collisions. We conclude by arguing that this result may be amenable to experimental verification through the use of quantum simulators.