Analytic continuation over complex landscapes

Abstract

In this paper we follow up the study of ‘complex complex landscapes’ (Kent-Dobias and Kurchan 2021 Phys. Rev. Res. 3 023064), rugged landscapes of many complex variables. Unlike real landscapes, the classification of saddles by index is trivial. Instead, the spectrum of fluctuations at stationary points determines their topological stability under analytic continuation of the theory. Topological changes, which occur at so-called Stokes points, proliferate among saddles with marginal (flat) directions and are suppressed otherwise. This gives a direct interpretation of the gap or ‘threshold’ energy—which in the real case separates saddles from minima—as the level where the spectrum of the hessian matrix of stationary points develops a gap. This leads to different consequences for the analytic continuation of real landscapes with different structures: the global minima of ‘one step replica-symmetry broken’ landscapes lie beyond a threshold, their hessians are gapped, and are locally protected from Stokes points, whereas those of ‘many step replica-symmetry broken’ have gapless hessians and Stokes points immediately proliferate. A new matrix ensemble is found, playing the role that GOE plays for real landscapes in determining the topological nature of saddles.