Pulsed Quantum Excitation

A two-level system (2LS) is the most fundamental building block of matter. Its response to classical light is well known, as it converts pulses of coherent light into antibunched emission. However, recent theoretical proposals have predicted that it is advantageous to illuminate two-level systems with Quantum Light; i.e., the light emitted from a quantum system. However, those proposals were done considering continuous excitation of the source of light. Here, we advance the field by changing the paradigm of excitation: we use the emission of a 2LS, itself driven by a laser pulse, to excite another 2LS. Thus, we present a thorough analysis of Resonance Fluorescence under pulsed quantum excitation and show, in particular, that the emission from a 2LS driven with quantum light is more antibunched and more indistinguishable than if it were driven with classical light. Our results reinforce the claim of the advantage of the excitation with quantum light, provide support to the recent experimental observations, and can be used as a road-map for the future of light-matter interaction research.