On Holographic Insulators and Supersolids

TL;DR

This paper constructs holographic models resembling Mott insulators and supersolids, analyzing their ground states, conductivity properties, and IR fixed points within Einstein-Maxwell-scalar systems.

Contribution

It introduces holographic realizations of insulator and supersolid phases, including methods to compute conductivity gaps and Drude weights, supported by numerical RG flow analysis.

Findings

Real part of AC conductivity exhibits a hard gap and discrete spectrum.

Momentum dissipation removes delta functions in conductivity.

Identifies IR fixed points of the ground states in holographic models.

Abstract

We obtain holographic realizations for systems that have strong similarities to Mott insulators and supersolids, after examining the ground states of Einstein-Maxwell-scalar systems. The real part of the AC conductivity has a hard gap and a discrete spectrum only. We add momentum dissipation to resolve the delta function in the conductivity due to translational invariance. We develop tools to directly calculate the Drude weight for a large class of solutions and to support our claims. Numerical RG flows are also constructed to verify that such saddle points are IR fixed points of asymptotically AdS_4 geometries.