Impact of phonon lifetimes on the single-photon indistinguishability in quantum emitters based on two-dimensional materials

Many advanced quantum technologies rely on quantum interference of indistinguishable photons. Quantum emitters made from 2D semiconductors promise cost-efficient single-photon sources. Here, the authors report a fundamental reduction of the achievable photon indistinguishability compared to 3D systems due to increased exciton-phonon coupling efficiency. In particular, coherence is affected by the finite phonon lifetime in the 2D material. Although embedding the quantum emitters in a cavity partly remedies decoherence effects through Purcell enhancement, a maximum achievable indistinguishability of below 50% is predicted.