Atomic tweak turns silicon into high-efficiency quantum light source

The article reports a significant advance in quantum photonics achieved by a subtle atomic modification in silicon. Researchers demonstrated that replacing the common hydrogen isotope (protium) with its heavier isotope (deuterium) within a specific silicon defect called the T center dramatically improves silicon’s efficiency as a single-photon emitter. The T center, a defect consisting of two carbon atoms and one hydrogen atom embedded in silicon, emits photons at telecommunications wavelengths compatible with existing fiber-optic infrastructure, making it highly promising for quantum networks and photonic quantum computing. However, the T center previously suffered from energy loss through nonradiative decay—energy dissipated as vibrations rather than emitted light—which limited its performance. To investigate this, the team used ultra-pure silicon crystals and created T centers with different isotopic compositions, including protium, deuterium, and carbon-13 variants. Cooling the samples to near absolute zero allowed precise measurement of vibrational modes and photon emission characteristics. They found that substituting hydrogen with deuter