Crossovers between Time-Bin and Energy-Time Entanglement in Homodyned Resonance Fluorescence

We theoretically investigate photonic entanglement generated by homodyning resonance fluorescence from a two-level emitter with a phase-locked laser field. Under weak excitation, increasing the relative laser-field amplitude produces crossovers from time-bin to energy–time and back to time-bin entanglement. The intermediate energy–time regime occurs near amplitude matching, where destructive interference suppresses the single-photon component, allowing the two-photon contributions to dominate the coincidence signal. We evaluate the resulting photon statistics and first-order coherence and characterize the entanglement through violations of the CHSH Bell inequality in a Franson interferometer. This scheme provides a route to controlling photonic entanglement through linear optics and coherent interference.