Efficient High-Fidelity Flying Qubit Shaping

Single photon emission is the cornerstone of numerous quantum technologies, such as distributed quantum computing as well as several quantum internet and networking protocols. We find the upper limit for the photonic emission efficiency for imperfect emitters and show a path forward to optimize the fidelity. The outlined theory for stimulated Raman emission is applicable to a wide range of physical systems including quantum dots, solid state defects, and trapped ions, as well as various parameter regimes. Furthermore, the mathematical idea to use input-output theory for pulses to absorb the dominant emission process into the coherent dynamics, followed by a quantum trajectory approach has great potential to study other physical systems.