New laser producing "quantum light" invented

The National Institute of Informatics (NII, Director General, Masaru Kitsuregawa) Assistant Professor Tim Byrnes and the University of Mainz, have succeeded in devising a new light source that produces "quantum light". Quantum light is similar to laser light, but it has special quantum mechanical properties. In laser light, the photons making up the light do not feel each other's presence. All the photons have the property of phase coherence. Drawing an analogy with marching soldiers, all the photons walk in step. In quantum light, in addition to marching in step, the photons try to push each other out of the way. This property gives rise to entanglement between the photons, coined by Einstein as a "spooky action at a distance". Previously it was thought that it was very difficult to produce such types of quantum light, because photons by their very nature do not interact with each other. Before the discovery, no methods were available that could produce quantum light continuously and reliably. The research, led by Australian Tim Byrnes and co-authored by Peter van Loock and Yoshihisa Yamamoto, overcame this by taking advantage of some peculiar physics which occurs in semiconductor systems. In carefully fabricated structures the phenomenon of Bose-Einstein condensation can occur, an effect that was the subject of the Nobel Prize in 2001. The light leaking from the semiconductor was found that it possesses unusual quantum characteristics that could be used to create the quantum light. Such quantum light is expected to be useful for future quantum technology applications such as in secure transmission of information.