Measuring Spin-Charge Separation in a 1D Fermi Gas

We present progress on measurement of spin-charge separation in a two-component, strongly interacting, 1D gas of fermionic lithium. A characteristic feature of interacting 1D Fermi gases is that the velocity of a charge excitation propagates faster than a spin excitation. We create an excitation by applying a dipole force at the center of the cloud using a sheet of light. Depending on the detuning of this beam, we can either excite both spin species equally (charge excitation) or preferentially (spin excitation)\footnote{A. Recati, P. O. Fedichev, W. Zwerger, and P. Zoller, \textbf{Phys. Rev. Lett.} 90, 020401 (2003).}. Once this beam is turned off, the excitations propagate to the edges of the atomic cloud at a velocity determined by coupling strength. A magnetically tuned Feshbach resonance enables us to vary this coupling and map out the velocities of spin and charge excitations.