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.
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Practical source of single photons. Nature 529, 258 (2016). https://doi.org/10.1038/529258b