Interacting ultracold fermions in one dimension

Cold atoms provide a pristine and tunable platform for studying quantum gases in reduced dimensions. We report on our experimental studies of interacting fermions in quasi-1D, both in two-spin and single-spin systems, realized using combinations of the hyperfine sublevels of ⁶Li. In the two-spin case, we measure the low-energy collective excitations in the Tomonaga-Luttinger liquid regime, as a function of strong, repulsive interactions. We separately excite charge and spin modes via two-photon Bragg processes, and measure the dynamic structure factor for each mode at different interaction strengths, tuned via an s-wave Feshbach resonance. In the single-spin case, we observe the rate of collisional loss due to molecule formation near a p-wave Feshbach resonance [1]. Our results suggest a suppression of this loss process very close to the resonance for strong transverse confinement, as predicted due to the stretching of the molecular wavefunction in quasi-1D [2].

[1] Y. T. Chang et al, Phys. Rev. Lett. (to be published).
[2] Lihong Zhou and Xiaoling Cui, Phys. Rev. A 96, 030701 (2017)