Density-Matrix Renormalization Group Study of Trapped Imbalanced Fermi Condensates

TL;DR

This study uses the density-matrix renormalization group to analyze a one-dimensional trapped imbalanced Fermi condensate, revealing phase separation, FFLO phase characteristics, and the persistence of minority atoms at high imbalance.

Contribution

It demonstrates the application of DMRG to identify phase separation and FFLO order in a trapped imbalanced Fermi system, providing new insights into its quantum phases.

Findings

Flattened population difference at trap center

Phase separation between condensate and unpaired atoms

Sign change in order parameter indicating FFLO phase

Abstract

The density-matrix renormalization group is employed to investigate a harmonically-trapped imbalanced Fermi condensate based on a one-dimensional attractive Hubbard model. The obtained density profile shows a flattened population difference of spin-up and spin-down components at the center of the trap, and exhibits phase separation between the condensate and unpaired majority atoms for a certain range of the interaction and population imabalance $P$. The two-particle density matrix reveals that the sign of the order parameter changes periodically, demonstrating the realization of the Fulde-Ferrell-Larkin-Ovchinnikov phase. The minority spin atoms contribute to the quasi-condensate up to at least $P \simeq 0.8$. Possible experimental situations to test our predictions are discussed.