Quenched binary Bose-Einstein condensates: spin domain formation and coarsening

TL;DR

This paper investigates the dynamic formation and growth of spin domains in quenched quasi-1D two-component Bose-Einstein condensates, revealing instability-driven domain formation and coarsening processes validated by stochastic Gross-Pitaevskii simulations.

Contribution

It introduces a detailed analysis of spin domain formation and coarsening in quenched two-component BECs, linking experimental observations with stochastic Gross-Pitaevskii modeling.

Findings

Rapid amplification of spin fluctuations leads to domain formation.

Domains grow and coarsen over time as the system approaches equilibrium.

Experimental results align with stochastic Gross-Pitaevskii simulations.

Abstract

We explore the time evolution of quasi-1D two component Bose-Einstein condensates (BEC's) following a quench from one component BEC's with a ${\rm U}(1)$ order parameter into two component condensates with a ${\rm U}(1)\shorttimes{\rm Z}_2$ order parameter. In our case, these two spin components have a propensity to phase separate, i.e., they are immiscible. Remarkably, these spin degrees of freedom can equivalently be described as a single component attractive BEC. A spatially uniform mixture of these spins is dynamically unstable, rapidly amplifing any quantum or pre-existing classical spin fluctuations. This coherent growth process drives the formation of numerous spin polarized domains, which are far from the system's ground state. At much longer times these domains grow in size, coarsening, as the system approaches equilibrium. The experimentally observed time evolution is fully consistent with our stochastic-projected Gross-Pitaevskii calculation.