With the help of a semiconductor quantum dot, physicists at the University of Basel 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 the scientific journal Nature Communications together with colleagues from the 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.
Noise in the semiconductor
A team of scientists led by Dr. Andreas Kuhlmann and Prof. Richard J. Warburton from the University of Basel have already shown in past publications that the indistinguishability of the photons is reduced by the fluctuating nuclear spin of the quantum dot atoms. For the first time ever, the scientists have managed to control the nuclear spin to such an extent that even photons sent out at very large intervals are the same color.
Quantum cryptography and quantum communication are two potential areas of application for single-photon sources. These technologies could make it possible to perform calculations that are far beyond the capabilities of today’s computers.
This breakthrough highlights new possibilities for integrating high-definition full color displays in wearable electronics.
The scientific team, from the Institute for Basic Science (IBS) and Seoul National University, has developed an ultra-thin wearable quantum dot light emitting diodes (QLEDs). The electronic tattoo is based on current quantum dot light emitting diode (QLED) technology. Colloidal quantum dot (QLED’s) have attracted great attention as next generation displays. The quantum dots (QDs) have unique properties such as the color tunability, photo/air stability, and are printability on various substrates. The device is paper thin and can be applied to human skin like a sticker.
The team developed the high performance red, green, and blue QLED array, whose resolutions approach 2,500 pixels per inch. This resolution is far superior to other light emitting devices and displays on the market today including ones used in the latest smartphones. The technique is readily scalable over large area. Devices are adaptable to deformed states and thereby built on the unconventional curvilinear substrates including surfaces of various objects. Further mechanical deformations, such as stretching or wrinkling, are also adopted in this technology, which enables QLEDs on the human skin. This breakthrough highlights new possibilities for integrating high-definition full color displays in wearable electronics.
Read more: QLEDs Meet Wearable Devices