Telecom-wavelength nonclassical light from single In(Ga)As quantum dots

The prospective construction of global quantum communication networks via optical glass fibers, aiming, e. g., at intrinsically secure transmission channels, substantially benefits from sources of single photons and pairs of entangled photons that cover the widely used telecommunication windows. This work addresses the optical and electronic properties of single semiconductor quantum dots which have been intentionally modified to provide emission of nonclassical light within the telecom O-band at 1.31 μm, and the telecom C-band at 1.55 μm.
The wavelength extension with respect to the well-known InAs/GaAs quantum dot system is obtained by two different strategies: First, a modification of the quantum dot material composition and capping layers, and second, the application of InP substrates. For both types of emitters, an analysis of the single-photon statistics is employed to obtain a quantum-optical characterization. An algorithm for a Monte Carlo simulation of the charge carrier dynamics in a nonresonantly excited quantum system is developed to capture the influence of the solid state environment.
As a third strategy, the frequency conversion of the single photons from InAs/GaAs quantum dots after the photon emission process is demonstrated. These conventional sources allow the application of well-established resonant spectroscopy techniques.