Dipolar evaporation of reactive molecules to below the Fermi temperature

TL;DR

This paper demonstrates a method to produce a quantum degenerate 2D Fermi gas of polar molecules using dipolar evaporation, electric fields, and optical lattices, enabling exploration of strongly interacting quantum phases.

Contribution

It introduces a novel approach combining electric fields and optical lattices to achieve quantum degeneracy in dipolar molecules, overcoming previous inelastic loss limitations.

Findings

Efficient dipolar evaporative cooling of KRb molecules.

Observation of Fermi statistics effects at quantum degeneracy.

Achievement of a 2D Fermi gas of polar molecules.

Abstract

Molecules are the building blocks of matter and their control is key to the investigation of new quantum phases, where rich degrees of freedom can be used to encode information and strong interactions can be precisely tuned. Inelastic losses in molecular collisions, however, have greatly hampered the engineering of low-entropy molecular systems. So far, the only quantum degenerate gas of molecules has been created via association of two highly degenerate atomic gases. Here, we use an external electric field along with optical lattice confinement to create a two-dimensional (2D) Fermi gas of spin-polarized potassium-rubidium (KRb) polar molecules, where elastic, tunable dipolar interactions dominate over all inelastic processes. Direct thermalization among the molecules in the trap leads to efficient dipolar evaporative cooling, yielding a rapid increase in phase-space density. At the onset of quantum degeneracy, we observe the effects of Fermi statistics on the thermodynamics of the molecular gas. These results demonstrate a general strategy for achieving quantum degeneracy in dipolar molecular gases to explore strongly interacting many-body phases.