The phases of deuterium at extreme densities

TL;DR

This paper explores the phases of deuterium at extreme densities, revealing a competition between ferromagnetic and nematic superconducting states, and identifying a novel phase with enhanced symmetry.

Contribution

It introduces a theoretical framework for understanding the phase structure of deuteron liquids at high densities, including the emergence of a new phase with SU(3) symmetry.

Findings

Dominant interactions are perturbative Coulomb interactions.

High-density ground state favors ferromagnetic phase.

A novel phase with SU(3) symmetry appears at lower densities.

Abstract

We consider deuterium compressed to higher than atomic, but lower than nuclear densities. At such densities deuterium is a superconducting quantum liquid. Generically, two superconducting phases compete, a "ferromagnetic" and a "nematic" one. We provide a power counting argument suggesting that the dominant interactions in the deuteron liquid are perturbative (but screened) Coulomb interactions. At very high densities the ground state is determined by very small nuclear interaction effects that probably favor the ferromagnetic phase. At lower densities the symmetry of the theory is effectively enhanced to SU(3), and the quantum liquid enters a novel phase, neither ferromagnetic nor nematic. Our results can serve as a starting point for investigations of the phase dynamics of deuteron liquids, as well as exploration of the stability and dynamics of the rich variety of topological objects that may occur in phases of the deuteron quantum liquid, which range from Alice strings to spin skyrmions to Z_2 vortices.