Tue October 26, 2021 4:00 pm
CUA Seminar – Randy Hulet: Spin-Charge Separation in a Strongly Interacting 1D Fermi Gas
Location:Zoom
Randy Hulet, Rice
Electronic excitations in three-dimensions are usually particle-like and well-described by the Landau Fermi liquid theory. In 1D, however, strong correlations between electrons are enhanced, resulting in collective excitations that are sound-like waves of either density or spin. These excitations may be understood by the Tomonaga-Luttinger liquid theory as bosonic density and spin waves arising from power-law correlations. The differing speeds of these waves are a striking manifestation of strong correlations, which comprise the celebrated spin-charge separation.
We use Bragg spectroscopy with a 1D Fermi gas of 6Li atoms to measure the dynamic structure factor of each mode in the small momentum regime. Spontaneous emission is suppressed by using the narrow 2S-3P ultra-violet transition. For strong interactions, we observe that the speed of the charge wave increases with increasing interaction strength, while the speed of the spin-wave decreases, as expected. Both excitations propagate at the Fermi velocity as the interactions are tuned to zero. We also observe the nonlinear Luttinger liquid for moderate excitation energies. Quantum simulation with ultracold atoms, as demonstrated here, can facilitate quantitative comparison with theory for some of the most exotic many-body phenomena.
4pm – Refreshments (in both 26-214 and Jefferson 450)
4:30 – Seminar start (via Zoom)