Kiel University researchers find light links in boron nitride

Study published in Advanced Functional Materials

Professor Nahid Talebi led the investigation from the Institute of Experimental and Applied Physics. The research team examined hexagonal boron nitride, a material only a few atomic layers thick. They illuminated this substance with laser light to analyze the subsequently emitted signals. In addition to known emissions from point defects, the group detected another specific light signal. This new signal possessed less energy than the incoming laser light used for excitation.

Defects allow forbidden phonon interactions

The energy difference in the light corresponds to specific phonons within the atomic lattice. According to standard crystal symmetry rules, these particular phonons should not participate in such scattering. However, measurements show that tiny irregularities in the structure change this outcome. These point defects act as quantum emitters that emit individual light particles. The interaction between these emitters and phonons enables coherent light emission despite symmetry constraints.

Electron beams confirm defect processes

Researchers also excited the material with an electron beam to narrow down the cause of the signal. Both laser and electron beam excitations produced the known light emission from the defects. The study suggests these findings could enable new optical and quantum technology applications. The ordered relationship between quantum states is maintained during this specific interaction process.