Protocol to engineer Fulde-Ferrell-Larkin-Ovchinnikov states in a cold Fermi gas

TL;DR

This paper presents a two-step experimental protocol to engineer and stabilize Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states in a cold Fermi gas, enabling controlled studies of these exotic superfluid phases.

Contribution

The authors introduce a novel two-step method combining phase imprinting and RF sweeps to create stable FFLO states in a cold Fermi gas, which can be implemented with high fidelity in current experiments.

Findings

Protocol can produce stable FFLO states with high fidelity.

Applicable across a wide range of interaction strengths.

Feasible with existing experimental setups.

Abstract

We propose a two-step experimental protocol to directly engineer Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states in a cold two-component Fermi gas loaded into a quasi-one-dimensional trap. First, one uses phase imprinting to create a train of domain walls in a superfluid with equal number of $\uparrow$- and $\downarrow$-spins. Second, one applies a radio-frequency sweep to selectively break Cooper pairs near the domain walls and transfer the $\uparrow$-spins to a third spin state which does not interact with the $\uparrow$- and $\downarrow$-spins. The resulting FFLO state has exactly one unpaired $\downarrow$-spin in each domain wall and is stable for all values of domain-wall separation and interaction strength. We show that the protocol can be implemented with high fidelity at sufficiently strong interactions for a wide range of parameters available in present-day experimental conditions.