# Holographic Duals of Inhomogeneous Systems: The Rainbow Chain and the Sine-Square Deformation Model

## TL;DR

This paper develops a holographic framework to analyze inhomogeneous quantum systems, specifically the rainbow chain and SSD model, by relating their entanglement entropy to different spacetime foliations, verified through numerical methods.

## Contribution

It introduces a holographic approach to inhomogeneous systems using BTZ spacetime foliations, providing new insights into their entanglement properties.

## Key findings

- Holographic entanglement entropy matches numerical results.
- Different spacetime slicings capture various inhomogeneous phenomena.
- The approach applies to a range of inhomogeneous theories.

## Abstract

A holographic dual description of inhomogeneous systems is discussed. Notably, finite temperature results for the entanglement entropy in both the rainbow chain and the SSD model are obtained holographically by choosing appropriate foliations of the BTZ spacetime. Other inhomogeneous theories are also discussed. The entanglement entropy results are verified numerically, indicating that a wide variety of inhomogeneous field theory phenomenology can be seen in different slicings of asymptotically $AdS_3$ spacetimes.