Direct and ultrafast probing of quantum many-body interaction and Mott-insulator transition through coherent two-dimensional spectroscopy

TL;DR

This paper introduces a method using coherent two-dimensional spectroscopy for direct, ultrafast probing of quantum many-body interactions and the Mott-insulator transition, revealing interaction dynamics through spectral features.

Contribution

It presents a novel approach to directly measure and analyze quantum many-body interactions and phase transitions on ultrafast timescales using 2D spectroscopy.

Findings

Off-diagonal peaks indicate moderate interactions.

Peaks coalesce into a single diagonal peak near the Mott transition.

Spectral evolution reveals ultrafast interaction dynamics.

Abstract

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. Up to a moderate interaction strength, the inter-particle 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 Mott-insulating phase in the strongly interacting regime. 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.