Emergent Loss Pathways in a Spin-imbalanced Three-component Fermi Gas

In a spin-balanced three-component Fermi gas, decay is typically modeled by three-body recombination, where each event leads to the loss of one atom from each spin component, provided the trap potential is sufficiently shallow. However, this conventional picture was recently challenged in an experiment in which the relative populations of spin species were varied [1]. The experiment, conducted with a spin-population-imbalanced three-component Fermi gas of ⁶Li, revealed anomalous decay behavior contradicting the standard understanding of three-body recombination. The gas included three distinct spin states in the lowest hyperfine Zeeman levels, and the system was probed at two magnetic fields where three tunable s-wave Feshbach resonances induced changes in the scattering properties for the different spin pairs. Initially, it was assumed that the loss rate for each species followed the standard form dn_i/dt = −L<span style="font-size:10.8333px">3n₁n₂n₃. This was indeed valid when all three s-wave scattering lengths were negative. However, this assumption no longer held when one scattering length became infinite and the others were large and positive. To reconcile the model with the experimental data, an additional term proportional to the relative population of each species was required. This modification indicates that the species with higher concentrations suffer a higher loss rate. In this presentation, I will discuss a theoretical analysis to understand the source of this anomaly and explore the underlying mechanisms that lead to this modified loss behavior in the system.

References

[1] Grant L. Schumacher et al. Observation of Anomalous Decay of a Polarized

Three-Component Fermi Gas. 2023. arXiv: 2301.02237 [cond-mat.quant-gas].

url: https://arxiv.org/abs/2301.02237.