New molecular coating method improves quantum photon purity by 87%

Researchers at Northwestern University have developed a novel molecular coating technique that significantly enhances the purity and reliability of single-photon sources critical for quantum technologies. By applying a layer of PTCDA molecules onto tungsten diselenide, an atomically thin semiconductor known for its single-photon emission at atomic defects, the team achieved an 87% improvement in photon spectral purity. This coating protects the fragile quantum emitters from atmospheric contaminants like oxygen, which previously caused variability and noise in photon production, without altering the semiconductor’s intrinsic electronic properties. The PTCDA coating not only stabilizes the photon emission but also uniformly shifts the photon energy to lower levels, beneficial for quantum communication devices. This uniformity and improved control over photon emission are essential for developing scalable, tunable, and stable single-photon sources, which are foundational for quantum computing, sensing, and secure quantum communication networks. The researchers plan to extend this approach to other semiconductor materials and explore electrically driven photon emission, aiming to advance toward interconnected quantum networks and