Convective Boson-Fermion pairing model constructed by oscillating one-dimensional optical superlattice

TL;DR

This paper introduces a convective boson-fermion pairing model in ultracold atoms within optical superlattices, revealing topological states, phase transitions, and low-energy observable pairing phenomena.

Contribution

It develops a novel convective pairing theory for boson-fermion mixtures in optical lattices, including topological classification and phase transition analysis.

Findings

Stable pairing states exist only in specific momentum zones.

The energy spectrum is complex with topological winding number classification.

Maximum critical temperature occurs at negative fermion chemical potential.

Abstract

Boson-fermion mixture exist in nature as quark-gluon plasma and $^3$He-$^4$He mixture. We proposed a convective boson-fermion pairing theory, that can be implemented by ultracold atoms in optical superlattice transformation between different configurations. This transformation may induce the collision and division between boson and fermion, which defines a theoretical convective pairing state. The paring Hamiltonian is Hermitian but it always generate a complex energy spectrum. Each finite gap state can be classified by a topological winding number. The stable pairing state only exists for certain discrete momentum vector zones. An unstable linear dispersion connects two neighboring stable pairing states. The boson-fermion gap function controls the momentum gap space between two neighboring pairing state. The critical temperature of transition from a gapped to gapless phase shows a maximal value at negative fermion chemical potential. The density of state for the pairing excitation diverges at low energy, thus most pairing states are observable at low energy.