Atomic number fluctuations in a mixture of two spinor condensates

TL;DR

This paper investigates particle number fluctuations in a mixture of two spin-1 atomic condensates, revealing unique fragmentation and fluctuation features in the AA phase through analytical and numerical methods.

Contribution

It provides a comprehensive analysis of ground state fluctuations in mixed spinor condensates, highlighting new fragmentation phenomena in the AA phase.

Findings

Fragmented ground states in the AA phase.

Distinct atom number fluctuation characteristics from single condensates.

Numerical validation of analytical predictions.

Abstract

We study particle number fluctuations in the quantum ground states of a mixture of two spin-1 atomic condensates when the interspecies spin-exchange coupling interaction $c_{12}\beta$ is adjusted. The two spin-1 condensates forming the mixture are respectively ferromagnetic and polar in the absence of an external magnetic (B-) field. We categorize all possible ground states using the angular momentum algebra and compute their characteristic atom number fluctuations, focusing especially on the the AA phase (when $ c_{12}\beta >0$), where the ground state becomes fragmented and atomic number fluctuations exhibit drastically different features from a single stand alone spin-1 polar condensate. Our results are further supported by numerical simulations of the full quantum many-body system.