Quantum phase transitions in semi-local quantum liquids

TL;DR

This paper explores various unconventional quantum critical points in gauge-gravity duality, revealing new phenomena like infinite towers of states and hybridized sectors, extending understanding beyond traditional Landau-Ginsburg-Wilson theory.

Contribution

It introduces and analyzes three novel types of quantum critical points in holographic models, including bifurcating, hybridized, and marginal critical points, with unique properties.

Findings

Identification of bifurcating critical points with confinement-driven transitions.

Discovery of infinite spiral structures in nonlinear response.

Connection of marginal critical points to Marginal Fermi Liquid behavior.

Abstract

We consider several types of quantum critical phenomena from finite-density gauge-gravity duality which to different degrees lie outside the Landau-Ginsburg-Wilson paradigm. These include: (1) a "bifurcating" critical point, for which the order parameter remains gapped at the critical point, and thus is not driven by soft order parameter fluctuations. Rather it appears to be driven by "confinement" which arises when two fixed points annihilate and lose conformality. On the condensed side, there is an infinite tower of condensed states and the nonlinear response of the tower exhibits an infinite spiral structure; (2) a "hybridized" critical point which can be described by a standard Landau-Ginsburg sector of order parameter fluctuations hybridized with a strongly coupled sector; (3) a "marginal" critical point which is obtained by tuning the above two critical points to occur together and whose bosonic fluctuation spectrum coincides with that postulated to underly the "Marginal Fermi Liquid" description of the optimally doped cuprates.