Shapiro-like Resonance in Ultracold Molecule Production via an Oscillating Magnetic Field

TL;DR

This paper investigates Shapiro-like resonances in ultracold molecule production using oscillating magnetic fields, revealing how resonance profiles are affected by temperature, amplitude, and many-body effects, with implications for optimizing molecular yields.

Contribution

The study provides a theoretical model explaining resonance behaviors and predicts a maximum molecular yield ceiling in uncondensed clouds, extending understanding of ultracold molecule formation.

Findings

Resonance profiles fit Lorentzian functions.

Line widths broaden with amplitude and duration.

Maximum yield in uncondensed clouds is about 1/3.

Abstract

We study the process of production of ultracold molecules from ultracold atoms using a sinusoidally oscillating magnetic field modulation. When the magnetic field is resonant roughly with the molecular binding energy, Shapiro-like resonances are observed. Their resonance profiles are well fitted by the Lorentzian functions. The line widths depend on both the amplitude and the duration of the applied modulations, and are found to be dramatically broadened by thermal dephasing effect. The resonance centers shift due to both many-body effect and finite temperature effect. Our theory is consistent with recent experiment (S. T. Thompson, E. Hodby, and C. E. Wieman, Phys. Rev. Lett. 95, 190404 (2005)). Our model predicts a 1/3 ceiling for the molecular production yield in uncondensed ultracold atomic clouds for a long coupling time, while for the condensed atoms the optimal conversion yield could be beyond the limit.