A novel holographic quantum phase transition and butterfly velocity

TL;DR

This paper investigates quantum phase transitions and butterfly velocity behaviors in an Einstein-Maxwell-dilaton-axions model, revealing new mechanisms and the role of butterfly velocity as a probe for phase transitions.

Contribution

It identifies two mechanisms driving quantum phase transitions and introduces a novel QPT in metal phases, highlighting butterfly velocity as an effective probe.

Findings

Butterfly velocity exhibits local extrema at QPTs.

Different IR geometries govern distinct phases.

A new QPT mechanism related to IR instability was discovered.

Abstract

In this paper, we make a systematical and in-depth exploration on the phase structure and the behaviors of butterfly velocity in an Einstein-Maxwell-dilaton-axions (EMDA) model. Depending on the model parameter, there are two kinds of mechanisms driving quantum phase transition (QPT) in this model. One is the infrared (IR) geometry to be renormalization group (RG) unstable, and the other is the strength of lattice deformation leading to some kind of bifurcating solution. We also find a novel QPT in the metal phases. The study on the behavior of the butterfly velocity crossing QPT indicates that the butterfly velocity or its first derivative exhibiting local extreme depends on the QPT mechanism. Further, the scaling behaviors of the butterfly velocity in the zero-temperature limit confirm that different phases are controlled by different IR geometries. Therefore, the butterfly velocity is a good probe to QPT and it also provides a possible way to study QPT beyond holography.