Generating triggered single and entangled photons with a semiconductor source

Young, Robert and Stevenson, R. Mark and Hudson, A. and Atkinson, Paola and Cooper, Ken and Ritchie, David A. and Shields, Andrew J. (2007) Generating triggered single and entangled photons with a semiconductor source. In: Quantum Communication and Security :. NATO Science for Peace and Security Series - D: Information and Communication Security Volume 11 . IOS Press, pp. 146-154. ISBN 978-1-58603-749-9

Abstract

For scalable applications of optical quantum information it is desirable to have a well controlled source of photons, producing single photons or entangled-pairs on-demand. The finite delay following decay of an exciton confined in a quantum dot makes them a good source of single photons, we demonstrate this, triggering the emission with a pulsed laser. Currently the most widely used techniques for generating entangled photon pairs are nonlinear optical processes, such as parametric down conversion, which produces a probabilistic number of pairs per excitation cycle. Such a source is of limited use in quantum information/processing applications where a regular stream of single entangled photon pairs is preferable. We produced such a triggered source from a semiconductor device for the first time, using the two-photon cascade from a biexciton confined in a single quantum dot. We demonstrate a fidelity of 70% for the emission from the biexciton cascade to the expected bell state. Single quantum dots could prove to be the first robust and compact triggered source of entangled photons.