Ultrafast dephasing in strongly correlated systems

Abstract

AbstractUsing projection techniques we derive the equation of motion for the third‐order nonlinear optical polarization of a strongly correlated system. We do not assume a Hartree–Fock ground state, but include the ground state correlations via time‐independent interaction parameters and energies. Our theory can be used to describe the ultrafast nonlinear optical response of a strongly correlated cold electron gas, such as the two‐dimensional electron gas in the quantum Hall effect regime. For this system, we show that the collective electronic excitations lead to a time‐dependent coupling of the Landau level magnetoexcitons and a strong non‐Markovian exciton dephasing. We discuss the signatures in the transient four‐wave‐mixing spectrum.