Probing collective dynamics in semiconductors: from nonlinear spectroscopy to entangled photon probes

Abstract

We investigate collective dynamics in molecular and hybrid semiconductors using nonlinear and quantum spectroscopies. We first present excitation correlation photoluminescence studies of molecular polariton condensates, revealing transient coherence buildup often obscured in steady-state observations. Additionally, we use coherent two-quantum spectroscopy to resolve biexcitonic correlations and many-body couplings in lead-halide perovskites. Bridging these studies with Quantum Information Science, we introduce emerging experimental methodologies utilizing frequency-entangled biphotons. Motivated by our recent theoretical frameworks on polariton scattering, we describe high-efficiency sources and hyperspectral imaging techniques designed to map spatial-spectral mode structures. We demonstrate that quantum observables, specifically joint spectral intensity, directly encode material entanglement entropy, establishing a rigorous pathway to access nonlinear interactions in complex environments.