Single-photon transistor

Will photons ever complement electrons in future devices? Photons are easy to use, travel at the speed of light and, unlike electrons, almost never interact with one another. These characteristic features make them very attractive for devices for quantum information processing, quantum computation and for transmitting quantum information over large distances with minimal perturbation and loss. Such quantum devices require optical transistors and switches that are operated by single photons. In spite of the fundamental scientific interest, their practical realization is challenging, and a robust, practical approach has yet to emerge. Here, I propose a novel approach to develop a single-photon triggered all-optical transistor in which single photons emitted from a single quantum dot will control the direction and the intensity of the laser beams emerging from a laser-pumped atomic vapor. The proposed approach merges the advantages of two highly successful scientific fields: semiconductors physics and atomic physics. The use of semiconductor quantum dots will enable easy integration with modern quantum electronics and photonics, where quantum operations and circuits have already been successfully demonstrated. Furthermore, coupling solid state quantum dots to atomic transitions opens a new route to advanced experiments such as single photon memories with slow light and indistinguishable photons from independent quantum dots.