Single photon generation from quantum dots: recent advances, challenges and future directions

A single photon source (SPS) is a device designed to emit photons, one at a time, enabling precise control over quantum states, unlike classical light sources that produce interfering streams. This capability is crucial for secure communication protocols such as quantum key distribution and for quantum networks, where single photons act as carriers of quantum information. Recent advancements have led to various SPS technologies, including quantum dots (QDs), atom-like emitters, and color centers in diamonds. Among these, QDs, semiconductor nanocrystals, have gained significant attention due to their unique optical and electronic properties derived from quantum confinement effects. They offer size-dependent tuning of emission wavelengths, high photoluminescence efficiency, and discrete energy levels, making them ideal for single photon applications while exhibiting scalability and low background noise. This review provides a comprehensive overview of recent advancements in quantum dot-based SPSs operating at room temperature, highlighting their optical properties, essential performance metrics, and the latest developments in single photon generation. It also discusses strategies to mitigate blinking and improve photon statistics through techniques such as plasmonic nanocavity and ligand exchange. The review concludes by outlining the challenges faced in the field and discussing potential solutions.