The effects of combined external electric and magnetic fields on elastic collisions in ultracold Li-Rb mixtures are studied using recently obtained experimentally verified potentials. Our analysis provides both quantitative predictions for and a detailed physical interpretation of the phenomena arising from electric-field-induced interactions. It is shown that the electric field shifts the positions of intrinsic magnetic Feshbach resonances, generates copies of resonances previously restricted to a particular partial-wave collision to other partial-wave channels, and splits Feshbach resonances into multiple resonances for states of nonzero angular momenta. It was recently observed that the magnetic dipole-dipole interaction can also lift the degeneracy of a
p-wave state splitting of the associated
p-wave Feshbach resonance into two distinct resonances at different magnetic fields. Our work shows that the splitting of the resonances produced by an applied electric field is more than 1 order of magnitude larger. This phenomenon offers a complementary way to produce and tune an anisotropic interaction and to study its effect on the many-body physics of heteronuclear atomic gases.
The heteronuclear atomic collision in the presence of a radio frequency (RF) electric field and a dc magnetic field is investigated theoretically by using the asymptotic bound state model. A RF field can be used to modify Feshbach resonance by choosing suitable intensity and frequency. The control mechanism is based on the interaction of the RF electric field with the instantaneous dipole moment of the collision atomic pair. We find an interesting phenomenon: the character exchange of the Feshbach resonances and resonance interference modulated by the RF field takes place in the ultracold collision of 6 Li and 40 K. This resonance interference may be used to modify the interactions in ultracold quantum gases.