Double universality of a quantum phase transition in spinor condensates: the Kibble-\.Zurek mechanism and a conservation law

TL;DR

This paper investigates a quantum phase transition in spinor condensates, revealing two distinct scaling laws related to spin fluctuations and domain formation, explained by a model incorporating conservation laws beyond the standard Kibble-Zurek mechanism.

Contribution

It introduces a model that explains the emergence of two scaling laws during a quantum phase transition, extending the Kibble-Zurek mechanism with conservation law considerations.

Findings

Two scaling laws observed for spin fluctuations and domain formation

Only the first scaling aligns with the standard Kibble-Zurek mechanism

The second scaling is explained by post-selection due to magnetization conservation

Abstract

We consider a phase transition from antiferromagnetic to phase separated ground state in a spin-1 Bose-Einstein condensate of ultracold atoms. We demonstrate the occurrence of two scaling laws, for the number of spin fluctuations just after the phase transition, and for the number of spin domains in the final, stable configuration. Only the first scaling can be explained by the standard Kibble-\.Zurek mechanism. We explain the occurrence of two scaling laws by a model including post-selection of spin domains due to the conservation of condensate magnetization.