Single-photon sources are essential for quantum computers that encode information in light. Now, physicists have produced photons with high quality and at high rates.

Chao-Yang Lu and Jian-Wei Pan at the University of Science and Technology of China in Shanghai and their colleagues used a laser to excite an artificial atom in a semiconductor crystal, known as a quantum dot. By using finely tuned laser pulses, they produced individual photons with near-perfect uniformity. They crafted the crystal into a tiny pillar-shaped cavity to maximize the number of photons that escaped.

The device emitted 3.7 million high-quality photons per second — a rate that makes it good enough for practical applications, say the authors.

Another group, led by Pascale Senellart at the University of Paris-Saclay and her colleagues, has achieved comparable success using a similar technique.

Phys. Rev. Lett. 116, 020401 (2016); preprint on arXiv (2015)