Two-field optical methods to control magnetic Feshbach resonances

TL;DR

This paper demonstrates two-field optical control of magnetic Feshbach resonances in a $^6$Li Fermi gas, significantly extending the lifetime near the broad resonance and introducing a new theoretical model for light-induced loss spectra.

Contribution

It introduces a novel two-field optical tuning method for Feshbach resonances and a continuum-dressed basis model that accurately predicts loss spectra.

Findings

Optical tuning of Feshbach resonances by up to 3 G

Increase in lifetime from 0.5 ms to 0.4 s near the broad resonance

Model accurately matches experimental loss spectra for both resonances

Abstract

Using an optically-trapped mixture of the two lowest hyperfine states of a $^6$Li Fermi gas, we observe two-field optical tuning of the narrow Feshbach resonance by up to 3 G and an increase in spontaneous lifetime near the broad resonance from $0.5$ ms to $0.4$ s. We present a new model of light-induced loss spectra, employing continuum-dressed basis states, that agrees in shape and magnitude with measurements for both broad and narrow resonances.