Selective Biexciton Generation Under Energy-Time Entangled Quantum Light in Quantum Dots

Abstract

Energy-time entangled photons provide new opportunities for controlling multiphoton absorption beyond classical limits. Here, we investigate biexciton generation in nanocrystal quantum dots driven by energy-time-entangled quantum light generated via a spontaneous parametric down-conversion process. We show that quantum correlations can enhance biexciton production while suppressing excitonic populations. By employing a three-level model, we demonstrate that biexciton generation depends nontrivially on the photon arrival-time entanglement and the pump bandwidth. Consequently, we find that maximizing efficiency requires an optimally shaped entangled photon field rather than simply scaling parameters for a monotonic improvement. Extending to a realistic CdSe/CdS core-shell quantum dots containing many excitonic states coupled to the quantum field, we demonstrate that increasing the bi-photon arrival time entanglement (closer arrival time) enhances constructive pathway interference and expands accessible excitation channels while preserving a better energy conservation excitation than classical light when generating biexciton. Furthermore, tuning the time correlation properties enables selective excitation of closely spaced biexciton states. These results establish entangled quantum light as a powerful tool for selective excitation and control of nonlinear optical processes in quantum-confined systems.