Raman Spectroscopy of a Doped Fermi-Hubbard system

Inelastic neutron scattering is a valuable technique for studying the dynamics of magnetic excitations in solid-state systems. In this work, we develop an analogous technique for spectroscopy of magnetic excitations in cold atom Fermi-Hubbard systems, focusing on the interplay between these excitations and itinerant charge carriers. We use Raman transitions to inject magnons with a controlled momentum into a doped, spin-polarized insulator. We study the evolution of the spectra with doping starting from the magnonic limit in the absence of dopants. Scattering with holes dresses the magnons and leads to the emergence of a novel type of Fermi polaron, the magnon-Fermi polaron. We use Raman spectroscopy to study the dependence of the dispersion of this quasiparticle with interactions and doping. We discuss how this scheme may be extended to studying the dispersion of renormalized magnons in doped Hubbard antiferromagnets. We expect that our scheme will be broadly applicable to studying magnetic excitations in a wide range of correlated many-body states, including more exotic quasiparticles in quantum spin liquid states.