Ultracold Fermionic Feshbach Molecules of $^{23}$Na$^{40}$K

TL;DR

This paper reports the creation of ultracold, chemically stable fermionic $^{23}$Na$^{40}$K molecules with long lifetimes, demonstrating their open-channel character and potential for stable, strongly dipolar quantum gases.

Contribution

First demonstration of ultracold fermionic $^{23}$Na$^{40}$K molecules with stability and open-channel character, enabling future ground-state transfer and dipolar quantum gas studies.

Findings

Molecular lifetime exceeds 100 ms near Feshbach resonance

Molecular binding energy depends on magnetic field, indicating open-channel character

Significant singlet admixture suggests efficient ground state transfer

Abstract

We report on the formation of ultracold fermionic Feshbach molecules of $^{23}$Na$^{40}$K, the first fermionic molecule that is chemically stable in its ground state. The lifetime of the nearly degenerate molecular gas exceeds 100 ms in the vicinity of the Feshbach resonance. The measured dependence of the molecular binding energy on the magnetic field demonstrates the open-channel character of the molecules over a wide field range and implies significant singlet admixture. This will enable efficient transfer into the singlet vibrational ground state, resulting in a stable molecular Fermi gas with strong dipolar interactions.