Robustness in Projected Entangled Pair States

TL;DR

This paper investigates the stability of PEPS ground states under perturbations, introducing a checkable LTQO-based criterion that ensures local property stability and demonstrating its robustness under spectral gap-preserving perturbations.

Contribution

It introduces a practical LTQO-based criterion for assessing PEPS stability and proves its stability under certain perturbations, advancing understanding of PEPS robustness.

Findings

LTQO provides a checkable stability criterion for PEPS.

LTQO is stable under spectral gap-preserving perturbations.

PEPS with LTQO are stable under arbitrary perturbations.

Abstract

We analyze a criterion which guarantees that the ground states of certain many body systems are stable under perturbations. Specifically, we consider PEPS, which are believed to provide an efficient description, based on local tensors, for the low energy physics arising from local interactions. In order to assess stability in the framework of PEPS, one thus needs to understand how physically allowed perturbations of the local tensor affect the properties of the global state. In this paper, we show that a restricted version of the Local Topological Quantum Order (LTQO) condition provides a checkable criterion which allows to assess the stability of local properties of PEPS under physical perturbations. We moreover show that LTQO itself is stable under perturbations which preserve the spectral gap, leading to nontrivial examples of PEPS which possess LTQO and are thus stable under arbitrary perturbations.