Repulsively-bound exciton-biexciton states in high-spin fermions in optical lattices

TL;DR

This paper explores how spin-changing collisions and quadratic Zeeman effects can create stable, repulsively bound exciton-biexciton states in high-spin fermions within optical lattices, revealing new quantum composite phases.

Contribution

It introduces a novel mechanism for forming repulsively bound states in high-spin fermions and analyzes their properties and stability in optical lattices.

Findings

Identification of two types of exciton-biexciton composites.

Dependence of composite stability on spin-changing collisions and Zeeman effect.

Potential for stable quantum composite phases against inelastic collisions.

Abstract

We show that the interplay between spin-changing collisions and quadratic Zeeman coupling provides a novel mechanism for the formation of repulsively bound composites in high-spin fermions, which we illustrate by considering spin flips in an initially polarized hard-core 1D Mott insulator of spin-3/2 fermions. We show that after the flips the dynamics is characterized by the creation of two types of exciton-biexciton composites. We analyze the conditions for the existence of these bound states, and discuss their intriguing properties. In particular we show that the effective mass and stability of the composites depends non-trivially on spin-changing collisions, on the quadratic Zeeman effect and on the initial exciton localization. Finally, we show that the composites may remain stable against inelastic collisions, opening the possibility of novel quantum composite phases.