Electron-phonon interactions in crystals found to be quantized by a fundamental constant

Researchers at Tohoku University discovered that electron-phonon interactions in crystals are quantized rather than continuous, with coupling strength always appearing as integer multiples of a base unit tied to the fine-structure constant (α ≈ 1/137). Using terahertz spectroscopy, they found that approximately 1/137th of a phonon's energy transfers during each interaction. The phenomenon originates from a Compton scattering-like process where electrons interact with photons emitted by phonons. This universal quantum rule could enable precise material design for semiconductors, superconductors, and quantum devices, with potential applications in electronics and life sciences.