Trigger-based single photons generated on demand for quantum tech

Researchers in Japan have developed a laser-guided fabrication technique that enables precise placement of a single quantum light source—a color center—within a carbon nanotube. By suspending a carbon nanotube across a narrow trench and exposing it to iodobenzene vapor, they used a focused ultraviolet laser to trigger a localized chemical reaction that creates a defect acting as a quantum emitter. Continuous real-time monitoring of the nanotube’s photoluminescence allowed the team to stop the reaction immediately after forming a single color center, ensuring only one photon-emitting site was created at a controlled position with micrometer precision. This method overcomes previous challenges where multiple, unpredictable emission sites formed along the nanotube, which hindered practical quantum applications. This breakthrough is significant because carbon nanotubes can emit single photons at room temperature and at telecom wavelengths compatible with existing optical fiber networks, unlike many other materials that require extreme cooling. The ability to generate single photons on demand and at precise locations opens the door to scalable quantum phot