Quantum Simulation with Ultra-Cold Atoms: Spin-Charge Separation

Randy Hulet, Rice University
Location: C9000

Friday, 10 February 2023 02:30PM PST


We employ quantum simulation of interesting electronic materials using ultracold 6Li atoms, a composite fermion, as stand-ins for the electrons. Quantum simulation of this kind takes advantage of the capability to adhere to a theoretical model, while the tunability of model parameters enables quantitative comparison with theory.

As an example, I will describe interacting spin-1/2 fermions confined to one-dimensional (1D). The low energy excitations are most likely collective in low dimensions, and thus realizes the Luttinger liquid. The low energy excitations are bosonic sound waves that correspond to either spin-density or charge-density waves that, remarkably, propagate at different speeds, thus realizing a spin-charge separation.  This phenomena has been observed in electronic materials, but a quantitative analysis has proved challenging because of the complexity of the electronic structure and the unavoidable presence of impurities and defects. In collaboration with our theory colleagues, we made a direct theory/experiment comparison and found excellent agreement as a function of interaction strength. We found that it was necessary to include nonlinear corrections to the spin-wave dispersion arising from back-scattering, thus going beyond the Luttinger model. More recently, we explored the disruption of spin correlations with increasing temperature, an effect that destroys spin-charge separation.