Dynamics of vortex defect formation in two dimensional Coulomb crystals

TL;DR

This paper investigates how topological vortices form in two-dimensional Coulomb crystals during a phase transition, using simulations and theory to understand defect creation and relaxation dynamics.

Contribution

It demonstrates the formation of stable vortices during a structural phase transition in ion Coulomb crystals and connects defect density scaling to Kibble-Zurek theory.

Findings

Vortex defects are created during the phase transition.

Defect density scales with quench rate as predicted by Kibble-Zurek.

Vortex-antivortex pairs annihilate, leading to diffusive defect relaxation.

Abstract

We study the non-equilibrium dynamics of two dimensional planar ion Coulomb crystals undergoing a structural buckling transition to a three plane configuration, driven by a reduction of the transverse confining frequency. This phase transition can be theoretically modeled using a mapping to a two dimensional Ginzburg-Landau theory with complex order parameter field. We demonstrate that finite rate quenches result in creation of stable topological vortices, which are localized point regions around which the phase of the order parameter field winds a multiple of 2{\pi}. The density of the defects as a function of quench rate is investigated using molecular dynamics simulations and its scaling is shown to be consistent with Kibble-Zurek theory of defect formation. Following the quench, the annihilation of vortex and anti-vortex pairs results in the relaxation of defect density that follows a diffusive scaling with a logarithmic correction. This work highlights the potential for investigating complex non-equilibrium statistical physics of topological defects in an experimentally accessible ion trap setting.