Energy-time entanglement from a monolithically integrated quantum dot on silicon

Scalable quantum photonic technologies require deterministic sources of entangled photons that are compatible with established semiconductor manufacturing platforms. While self-assembled III-V semiconductor quantum dots are among the most promising sources of on-demand entanglement generation, their integration with silicon-based architectures remains a central challenge. Here, we demonstrate energy-time entanglement from a single InGaAs/GaAs quantum dot monolithically grown on a silicon substrate. Under resonant two-photon excitation, we achieve coherent control of the biexciton-exciton cascade, evidenced by the formation of dressed-states and Rabi oscillations. Using a four-channel Franson interferometer, we observe phase-dependent two-photon interference with visibilities up to (64.0 ± 7.0)% for a 80 ps integration window (and (49.4 ± 1.9)% for a 1600 ps window), approaching the threshold for Bell inequality violation at short timescales. Despite these constraints, the observation of Franson interference establishes monolithic III-V-on-silicon quantum dots as viable sources of energy-time entangled photons. These results represent a crucial step toward fully integrated, silicon-substrate-compatible quantum photonic circuits for large-scale quantum communication and information processing.