Semi-local quantum liquids

TL;DR

This paper explores the semi-local quantum liquid phase predicted by gauge/gravity duality, characterized by unique scaling and entropy properties, and discusses its emergence and relevance to various strongly interacting systems.

Contribution

It demonstrates the universal emergence of semi-local quantum liquids at intermediate energies and explores their potential relevance to heavy electron systems and high-temperature superconductors.

Findings

Semi-local quantum liquids exhibit finite spatial correlation length and infinite correlation time.

This phase appears universally at intermediate energies in holographic models.

The phase may be relevant to understanding strange metals and heavy fermion systems.

Abstract

Gauge/gravity duality applied to strongly interacting systems at finite density predicts a universal intermediate energy phase to which we refer as a semi-local quantum liquid. Such a phase is characterized by a finite spatial correlation length, but an infinite correlation time and associated nontrivial scaling behavior in the time direction, as well as a nonzero entropy density. For a holographic system at a nonzero chemical potential, this unstable phase sets in at an energy scale of order of the chemical potential, and orders at lower energies into other phases; examples include superconductors and antiferromagnetic-type states. In this paper we give examples in which it also orders into Fermi liquids of "heavy" fermions. While the precise nature of the lower energy state depends on the specific dynamics of the individual system, we argue that the semi-local quantum liquid emerges universally at intermediate energies through deconfinement (or equivalently fractionalization). We also discuss the possible relevance of such a semi-local quantum liquid to heavy electron systems and the strange metal phase of high temperature cuprate superconductors.