Igor Aharonovich

Inside a boron nitride crystal, defects sometimes occur — places where atoms are knocked out or sit where they shouldn't. One such defect, the B-center, can emit light: it absorbs energy and releases it as a single photon. It's like a tiny light bulb that only lights up when asked, without any stray glow.

A glowing spot on a crystal is like a firefly that you can wake not only with a flashlight but also with the warmth of your palm. Such spots, single-photon sources, can emit light one particle at a time, which is essential for quantum communication and computing.

A tiny defect in a boron nitride crystal behaves like a microscopic indicator bulb. Shine light on it, and it glows, with the shade shifting with temperature: the warmer it gets, the redder the glow.