Magnetic Field Dependence of Inelastic Collisions Near a Feshbach Resonance

José Paulo D'Incao, Brett D. Esry, Chris H. Greene

Jacob Roberts, N. R. Claussen, Simon L. Cornish +1 more

Inelastic collision rates for ultracold ${}^{85}\mathrm{Rb}$ atoms in the $F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2$, ${m}_{f}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}2$ state have been measured as a function of magnetic field. At 250 gauss (G), the two- and three-body loss rates were measured to be ${K}_{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(1.87\ifmmode\pm\else\textpm\fi{}0.95\ifmmode\pm\else\textpm\fi{}0.19)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}{\mathrm{cm}}^{3}/\mathrm{s}$ and ${K}_{3}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({4.24}_{\ensuremath{-}0.29}^{+0.70}\ifmmode\pm\else\textpm\fi{}0.85)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}25}{\mathrm{cm}}^{6}/\mathrm{s}$, respectively. As the magnetic field is decreased from 250 G towards a Feshbach resonance at 155 G, the inelastic rates decrease to a minimum and then increase dramatically, peaking at the Feshbach resonance. Both two- and three-body losses are important, and individual contributions have been compared with theory.

James R. Macdonald Lab

Jacob Roberts, N. R. Claussen, Simon L. Cornish +1 more

Inelastic collision rates for ultracold 85 Rb atoms in the F=2, m f =-2 state have been measured as a function of magnetic field.At 250 Gauss (G), the two-and three-body loss rates were measured to be K 2 =1.87±0.95±0.19x 10 -14 cm 3 /s and K 3 =4.24+0.70 -0.29 ±0.85 x 10 -25 cm 6 /s respectively.As the magnetic field is decreased from 250 G towards a Feshbach resonance at 155 G, the inelastic rates decrease to a minimum and then increase dramatically, peaking at the Feshbach resonance.Both two-and three-body losses are important, and individual contributions have been compared with theory.

J. C. Gay, Werner B. Schneider

Shi-Guo Peng, Shina Tan, Kaijun Jiang

It is well known that the magnetic Feshbach resonances of cold atoms are sensitive to the magnitude of the external magnetic field. Much less attention has been paid to the direction of such a field. In this work we calculate the scattering properties of spin polarized fermionic atoms in reduced dimensions, near a p-wave Feshbach resonance. Because of the spatial anisotropy of the p-wave interaction, the scattering has a nontrivial dependence on both the magnitude and the direction of the magnetic field. In addition, we identify an inelastic scattering process which is impossible in the isotropic-interaction model; the rate of this process depends considerably on the direction of the magnetic field. Significantly, an Einstein-Podolsky-Rosen entangled pair of identical fermions may be produced during this inelastic collision. This work opens a new method to manipulate resonant cold atomic interactions.