Feshbach resonances, molecular bound states and prospects of ultracold molecule formation in mixtures of ultracold K and Cs

TL;DR

This paper investigates the formation of ultracold KCs molecules via magnetoassociation, analyzing Feshbach resonances and scattering properties in different isotopic mixtures to guide experimental strategies.

Contribution

It provides detailed coupled-channel calculations of scattering lengths and Feshbach resonances for all three K-Cs isotopic combinations, offering new insights for ultracold molecule production.

Findings

Identification of Feshbach resonances with widths from below 1 nG to 5 G.

Calculation of bound-state energies as a function of magnetic field.

Strategies for cooling and molecule formation in different isotopic mixtures.

Abstract

We consider the possibilities for producing ultracold mixtures of K and Cs and forming KCs molecules by magnetoassociation. We carry out coupled-channel calculations of the interspecies scattering length for $^{39}$KCs, $^{41}$KCs and $^{40}$KCs and characterize Feshbach resonances due to s-wave and d-wave bound states, with widths ranging from below 1 nG to 5 G. We also calculate the corresponding bound-state energies as a function of magnetic field. We give a general discussion of the combinations of intraspecies and interspecies scattering lengths needed to form low-temperature atomic mixtures and condensates and identify promising strategies for cooling and molecule formation for all three isotopic combinations of K and Cs.