Controlling Collisions of Ultracold Atoms with dc Electric Fields

It is demonstrated that elastic collisions of ultracold atoms forming a heteronuclear collision complex can be manipulated by laboratory practicable dc electric fields. The mechanism of electric field control is based on the interaction of the instantaneous dipole moment of the collision pair with external electric fields. It is shown that this interaction is dramatically enhanced in the presence of a $p$-wave shape or Feshbach scattering resonance near the collision threshold, which leads to novel electric-field-induced Feshbach resonances.

Figure 1

Cross sections for elastic $s$-wave scattering (upper panel), elastic $p$-wave scattering (middle panel), and inelastic $s\to p$ transitions at an electric field strength of $30\mathrm{kV}/\mathrm{cm}$ (lower panel). The elastic scattering cross sections are computed at zero electric field. The collision energy is ${10}^{-7}{\mathrm{cm}}^{-1}$.

Figure 2

Left panels: Cross sections for elastic $s$-wave scattering (upper panel) and inelastic $s\to p$ transitions (lower panel) as a function of the electric field strength at the magnetic field magnitude 4709.6 G. Right panels: Elastic $s$-wave (solid curve) and $p$-wave (dashed curve) cross sections computed at zero electric field (upper panel) and $100\mathrm{kV}/\mathrm{cm}$ (lower panel). The collision energy is ${10}^{-7}{\mathrm{cm}}^{-1}$. The electric field not only couples the $s$ and $p$ states, but also shifts the positions of the $p$-wave resonances, thereby inducing the resonant variation of the $s$-wave cross section.

Figure 3

Variation of elastic $s$-wave scattering cross section at zero collision energy with the electric field in the presence of a $p$-wave shape resonance near threshold. The collision energy is ${10}^{-7}{\mathrm{cm}}^{-1}$. The two curves correspond to two slightly different positions of the resonance.