‘Ideal’ single-photon generator perfected

Quantum dot is key to Swiss-German development of single photon source.

With the help of a semiconductor quantum dot, physicists at the University of Basel. Switzerland, have developed a new type of light source that emits single photons. For the first time, the researchers have managed to create a stream of identical photons. They have reported their findings in Nature Communications together with colleagues from Germany’s University of Bochum.

A single-photon source never emits two or more photons at the same time. Single photons are important in the field of quantum information technology where, for example, they are used in quantum computers.

Alongside the brightness and robustness of the light source, the indistinguishability of the photons is especially crucial. In particular, this means that all photons must be the same color. Creating such a source of identical single photons has proven very difficult in the past.

However, quantum dots made of semiconductor materials are offering new hope. A quantum dot is a collection of a few hundred thousand atoms that can form itself into a semiconductor under certain conditions. Single electrons can be captured in these quantum dots and locked into a very small area. An individual photon is emitted when an engineered quantum state collapses.

Source: http://optics.org