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Researchers from Paderborn University, the University of Basel, and Ruhr University Bochum have developed a new method to generate nearly indistinguishable photons for quantum communication. Published in *Physical Review Letters*, their work uses special semiconductor nanostructures called quantum dots within an optical resonator. This setup accelerates a process known as "biexciton decay," where a molecule containing two bound excitons decays to produce two photons one after another.

Previously, generated photons suffered from temporal correlations or focus issues, reducing their quality to about 60% indistinguishability. The new approach achieves 90% indistinguishability. Lead author Timon Baltisberger explains that this "biexciton cascade" acts like a button press, emitting high-quality photons on demand. Dr. Stefan Schumacher notes that integrating the quantum dot into a specialized cavity controls and accelerates the light emission, similar to how lasers function.

Professor Richard Warburton states that these results align with theoretical predictions and suggest future improvements are possible through better control. The team found that photon purity is limited only by vibrations in the semiconductor’s crystal lattice, a phenomenon called "cavity feeding." Dr. Klaus Jöns emphasizes that this effect can be systematically minimized in future designs. Higher indistinguishability leads to lower error rates in data processing, making quantum dots a promising technology for mass-producing these particles.