Quantum Resonator as a Directional Quantum Emitter

Single-photon sources are essential for testing fundamental physics and for the development of quantum technologies. In this work a single-photon source is investigated, based on a two-photon Jaynes-Cummings system, where the resonator works as the quantum emitter rather than the two-level system. This role reversal provides certain advantages, such as robustness against losses from the two-level system (e.g., dephasing), as it remains in its ground state throughout the entire dynamics. This provides higher efficiency, purity, and indistinguishability compared to sources based on the usual Jaynes-Cummings model under the same parameter conditions in both models. Another advantage of this system is the possibility of direct conversion of a coherent excitation pulse with one photon on average to a single-photon pulse with efficiency, purity, and indistinguishability above $90\%$. Since the entire excitation pulse is consumed in the generation of a single photon, the system also minimizes energy waste. The potential for implementing the two-photon JC model across different platforms expands the possibilities for controlled single-photon generation in applications in quantum information processing and computation.