Characterizing Feshbach resonances in ultracold scattering calculations

Abstract

We describe procedures for converging on and characterizing zero-energy Feshbach resonances that appear in scattering lengths as a function of an external field. The elastic procedure is appropriate for purely elastic scattering, where the scattering length is real and displays a true pole. The regularized scattering length (RSL) procedure is appropriate when there is weak background inelasticity, so that the scattering length is complex and displays an oscillation rather than a pole, but the resonant scattering length $a_{\mathrm{res}}$ is close to real. The fully complex procedure is appropriate when there is substantial background inelasticity and the real and complex parts of $a_{\mathrm{res}}$ are required. We demonstrate these procedures for scattering of ultracold ${}^{85}$Rb in various initial states. All of them can converge on and provide full characterization of resonances, from initial guesses many thousands of widths away, using scattering calculations at only about 10 values of the external field.

9 pages, 5 figures

References in corpus (5)

• Feshbach resonances in ultracold atomic and molecular collisions: threshold behaviour and suppression of poles in scattering lengths
• Molecule formation in ultracold atomic gases
• Ultracold atom-molecule collisions and bound states in magnetic fields: tuning zero-energy Feshbach resonances in He-NH (3Sigma-)
• Feshbach resonances in ultracold 85Rb
• Feshbach spectroscopy of an ultracold mixture of ${}^{85}$Rb and ${}^{133}$Cs

Cited by in corpus (8)

• Pinpointing Feshbach Resonances and Testing Efimov Universalities in ${}^{39}$K
• Improved characterization of Feshbach resonances and interaction potentials between ${}^{23}$Na and ${}^{87}$Rb atoms
• Interaction potential for NaCs for ultracold scattering and spectroscopy
• Feshbach Spectroscopy of Cs Atom Pairs in Optical Tweezers
• Feshbach resonances and molecule formation in ultracold mixtures of Rb and Yb(${}^3$P) atoms
• Spin--spin interaction and magnetic Feshbach resonances in collisions of high-spin atoms with closed-shell atoms
• Formation of ultracold ${}^{39}$K${}^{133}$Cs Feshbach molecules
• Fitting ultracold resonances without a fit