Inhomogeneous state of few-fermion superfluids

TL;DR

This paper investigates inhomogeneous superfluid pairing in few-fermion systems, highlighting minimal configurations that exhibit pairing density variations and discussing how larger systems approach macroscopic superfluid behavior.

Contribution

It introduces the minimal few-fermion configurations that display inhomogeneous pairing and explores how increasing atom number transitions to macroscopic superfluidity.

Findings

Minimal three-fermion system shows inhomogeneous pairing density.

Larger systems with more than eight atoms approach macroscopic superfluid behavior.

Oblate traps with central barriers can probe pairing inhomogeneity experimentally.

Abstract

The few-fermion atomic gas is an ideal setting to explore inhomogeneous superfluid pairing analogous to the Larkin-Ovchinnikov state. Two up and one down-spin atom is the minimal configuration that displays an inhomogeneous pairing density whereas imbalanced systems containing more fermions present a more complex pairing topology. With more than eight atoms trapped the system approaches the macroscopic superfluid limit. An oblate trap with a central barrier offers a direct experimental probe of pairing inhomogeneity.