Polarized entangled Bose-Einstein condensation

TL;DR

This paper investigates the ground states of a two-species pseudospin-1/2 Bose-Einstein condensate with spin-exchange interactions, revealing a polarized entangled phase where unpaired atoms are spin-polarized alongside singlet pairs.

Contribution

It introduces the concept of polarized entangled Bose-Einstein condensation in a multi-component system with spin-exchange interactions and analyzes its effects on the condensate's properties.

Findings

Identification of parameter regimes with polarized entangled BEC

Demonstration of interplay between spin polarization and entanglement

Modification of Gross-Pitaevskii equations due to spin interactions

Abstract

We consider a mixture of two distinct species of atoms of pseudospin-1/2 with both intraspecies and Interspecies spin-exchange interactions, and find all the ground stats in a general case of the parameters in the effective Hamiltonian. In general, corresponding to the two species and two pseudo-spin states, there are four orbital wave functions into which the atoms condense. We find that in certain parameter regimes, the ground state is the so-called polarized entangled Bose-Einstein condensation, i.e. in addition to condensation of interspecies singlet pairs, there are unpaired atoms with spins polarized in the same direction. The interspecies entanglement and polarization significantly affect the generalized Gross-Pitaevskii equations governing the four orbital wave functions into which the atoms condense, as an interesting interplay between spin and orbital degrees of freedom.