A tiny laser beam touches a crystal for an instant, and inside, as if by magic, single quantum sparkles light up. This is no trick but a new way to create qubits, the working cells of future quantum computers. The material is silicon carbide, the same one already used in power electronics and LEDs. It contains special spots — defects where the crystal lattice is slightly disturbed. One such defect, the V2 center, behaves like an isolated atom: it can store quantum information and exchange it via light.
Previously, such defects had to be found among randomly occurring ones, making production slow and unpredictable. Now researchers take ready-made silicon carbide nanopillars and irradiate them with short pulses from an ultraviolet laser. The light knocks out carbon atoms, and V2 centers appear in their place. The number of defects grows elevenfold, and their quality is no worse than natural ones: narrow optical lines and stable spin — exactly what you need for reliable quantum communication.
Tests showed that the spin coherence time (how long a qubit 'remembers' its state) reaches 3.6 milliseconds. That's comparable to the best specially grown samples. The method works right inside finished devices — no need to disassemble or rework the chip. The laser can be aimed precisely at the desired spot, like a pen adding missing details to an already assembled mechanism.
Silicon carbide is cheap and produced on an industrial scale, unlike diamond — another popular material for quantum defects. If we can learn to stamp out qubits with a laser on an assembly line, quantum networks will become closer to reality. A spark lit by a beam could become the foundation of secure communication and powerful computation.
Silicon carbide is the same material used for brake discs in sports cars and mirrors for space telescopes. Now it will also find use in quantum electronics.