Radio-Frequency Manipulation of Fano-Feshbach Resonances in an Ultracold Fermi Gas of $^{40}$K

TL;DR

This paper demonstrates the use of radio-frequency fields to precisely control Fano-Feshbach resonances in ultracold $^{40}$K gases, enabling detailed spectroscopic measurements and manipulation of scattering properties near molecular states.

Contribution

It introduces a method for RF manipulation of Fano-Feshbach resonances in ultracold gases, providing high-accuracy molecular state locations for studying quantum crossover phenomena.

Findings

RF fields can modify scattering properties in ultracold gases.

Spectroscopic measurements of molecular levels near the continuum.

RF control enables exploration of BEC-BCS crossover regimes.

Abstract

Experimental control of magnetic Fano-Feshbach resonances in ultracold $^{40}$K Fermi gases, using radio-frequency (RF) fields, is demonstrated. Spectroscopic measurements are made of three molecular levels within 50 MHz of the atomic continuum, along with their variation with magnetic field. Modifying the scattering properties by an RF field is shown by measuring the loss profile versus magnetic field. This work provides the high accuracy locations of ground molecular states near the s-wave Fano-Feshbach resonance, which can be used to study the crossover regime from a Bose-Einstein condensate to a Bardeen-Cooper-Schrieffer superfluid in presence of an RF field.