Accurate calculation of elastic scattering properties of potassium and cesium atoms at ultracold temperatures

Abstract

In this paper, we calculate the scattering parameters for collision between potassium and cesium atoms at ultracold temperatures, such as s-wave scattering length, effective range and p-wave scattering length, by the quantum method and semiclassical method, respectively. The singlet and the triplet elastic scattering cross sections between 39K and Cs atoms at ultracold temperatures are dominated by s-wave scattering, and shape resonance occurs with the increase of collision energy. There exist pronounced g-wave and d-wave shape resonances for the singlet and the triplet cross sections, respectively. In addition, s-wave scattering lengths are calculated by using the degenerate internet state approximation for selected hyperfine states of 41KCs.

Measurement of129Xe frequency shift due to Cs—129Xe collisions

“…In previous measurements, the alkali-metal electron spins and the noble-gas nuclear spins are decoupled from each other at high magnetic field. [11][12][13][14][15] Therefore, the equations describing the electron and nuclear spins' polarization dynamics can be considered separately, simplifying the problem considerably. In our experiment, Cs and 129 Xe atoms are located at an ultralow magnetic field of about 100 nT, such that the frequency shifts due to spin-exchange are comparable with or larger than the Larmor frequencies.…”

“…[8,9] A common technique for producing large quantities of hyperpolarized 129 Xe is spin-exchange optical pumping (SEOP), and Cs is the best choice for SEOP. [10][11][12] The Fermi-contact hyperfine interaction α(R)K • S between the noble-gas nuclear spin K and the alkali-metal electron spin S is a fundamental aspect of SEOP. This interaction gives rise to complementary shifts in both the NMR frequency of the noble gas and the EPR frequency of the alkali-metal, and it can be well-described by effective magnetic fields with the appropriate enhancement factors: [13] δ B z a = 8π 3…”