Universal Threshold Laws for Dipolar Evaporation of Molecular Fermi Gases
Abstract
Fermi statistics suppress the elastic collisions that rethermalize a Fermi gas during evaporative cooling, creating a fundamental low-temperature bottleneck for producing quantum degenerate gases. We show that, for shielded single-component ultracold dipolar molecular Fermi gases in the Wigner threshold regime, this bottleneck is governed by universal threshold laws fixed by the effective dimensionality of the gas. In this regime, Fermi suppression of rethermalization scales quadratically with temperature in 3D but only linearly in 2D. Consequently, the thermalization-to-loss ratio is more favorable in 2D than in 3D, and these results suggest that 2D geometries are better suited for reaching deep degeneracy. We also present ab initio close-coupling calculations that agree well with experimental measurements on Fermi degenerate gases of KRb molecules, supporting our conclusions.
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BibTeX
@misc{xu2026universal,
title = {{Universal Threshold Laws for Dipolar Evaporation of Molecular Fermi Gases}},
author = {Kevin B. Xu and John L. Bohn and Reuben R. W. Wang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.22639},
eprint = {2610.22639},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.22639},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Universal Threshold Laws for Dipolar Evaporation of Molecular Fermi Gases
AU - Kevin B. Xu
AU - John L. Bohn
AU - Reuben R. W. Wang
PY - 2026
DA - 2026/10/15
PB - arXiv
DO - 10.48550/arxiv.2610.22639
UR - https://arxiv.org/abs/2610.22639
AB - Fermi statistics suppress the elastic collisions that rethermalize a Fermi gas during evaporative cooling, creating a fundamental low-temperature bottleneck for producing quantum degenerate gases. We show that, for shielded single-component ultracold dipolar molecular Fermi gases in the Wigner threshold regime, this bottleneck is governed by universal threshold laws fixed by the effective dimensionality of the gas. In this regime, Fermi suppression of rethermalization scales quadratically with temperature in 3D but only linearly in 2D. Consequently, the thermalization-to-loss ratio is more favorable in 2D than in 3D, and these results suggest that 2D geometries are better suited for reaching deep degeneracy. We also present ab initio close-coupling calculations that agree well with experimental measurements on Fermi degenerate gases of KRb molecules, supporting our conclusions.
ER -