Researchers have uncovered subtle optical signatures that could help distinguish atomic defects in a promising quantum material.

An atomic defect too small to see could leave a recognizable signature in laser light, giving scientists a new way to identify structures that may be useful for quantum technology. Researchers at the University at Buffalo have predicted how different atomic imperfections alter the optical behavior of hexagonal boron nitride (h-BN), a material made of boron and nitrogen atoms arranged in a honeycomb pattern.

Using computer simulations, the team examined 10 types of defects, including missing boron or nitrogen atoms and sites where carbon atoms had taken their place. Some defects were predicted to dramatically increase the light produced at twice or even three times the frequency of an incoming laser. The strength of these signals depended on the light’s polarization, which describes the orientation of its electric field.