Direct and ultrafast probing of quantum many-body interactions through coherent two-dimensional spectroscopy: From weak- to strong-interaction regimes

Interactions between particles in quantum many-body systems play a crucial role in determining the electric, magnetic, optical, and thermal properties of the system. The recent progress in the laser-pulse technique has enabled the manipulations and measurements of physical properties on ultrafast timescales. Here we propose a method for the direct and ultrafast probing of quantum many-body interaction through coherent two-dimensional (2D) spectroscopy. Using a two-band fermionic Hubbard model for the minimum two-site lattice system, we find that the 2D spectrum of a noninteracting system contains only diagonal peaks; the interparticle interaction manifests itself in the emergence of off-diagonal peaks in the 2D spectrum before all the peaks coalesce into a single diagonal peak as the system approaches the strongly interacting limit. The evolution of the 2D spectrum as a function of the time delay between the second and third laser pulses can provide important information on the ultrafast time variation of the interaction.

Automated summary

The proposed method uses 2D spectroscopy to directly probe quantum many-body interactions, providing insights into the electrical, magnetic, optical, and thermal properties of the system. Simulation results reveal distinct differences in the 2D spectrum between non-interacting and strongly interacting systems, highlighting the evolution of interactions over time delays.