Ground states and dynamics of population-imbalanced Fermi condensates in one dimension

TL;DR

This paper uses advanced numerical methods to explore the ground states and dynamics of population-imbalanced 1D Fermi gases, revealing the prevalence of LO states and their behavior under excitations.

Contribution

It provides the first comprehensive phase diagram of 1D imbalanced Fermi gases showing LO states and analyzes their real-time dynamics after spin-flip excitations.

Findings

LO state realized over wide parameter range

Phase diagram with two distinct states identified

Majority atoms mainly contribute to LO quasi-condensate

Abstract

By using the numerically exact density-matrix renormalization group (DMRG) approach, we investigate the ground states of harmonically trapped one-dimensional (1D) fermions with population imbalance and find that the Larkin-Ovchinnikov (LO) state, which is a condensed state of fermion pairs with nonzero center-of-mass momentum, is realized for a wide range of parameters. The phase diagram comprising the two phases of i) an LO state at the trap center and a balanced condensate at the periphery and ii) an LO state at the trap center and a pure majority component at the periphery, is obtained. The reduced two-body density matrix indicates that most of the minority atoms contribute to the LO-type quasi-condensate. With the time-dependent DMRG, we also investigate the real-time dynamics of a system of 1D fermions in response to a spin-flip excitation.