GaSb/GaAs quantum ring single photon LEDs (QR_SPLEDs)

Quantum technologies exploit the exotic properties of nature described by quantum mechanics to deliver devices with unprecedented speed, accuracy or completely new functionalities. Quantum cryptography is one such technology: communication whose security is guaranteed by fundamental laws of quantum mechanics. The implementation of quantum cryptography relies on the ability to generate very low intensities or even single photons of light on demand . Several different physical systems have been used to generate single photons, but very few of them are suitable for commercial production. An ideal single photon source should be fast, cheap and efficient, operate at room temperature, and emit photons at the wavelengths used in existing optical-fibre telecoms networks. A practical single photon source is expected to be somewhat like a type of semiconductor laser diode called a vertical cavity surface emitting laser (VCSEL ). We will assess the feasibility of mass-producing low-cost single-photon sources in the form of single-photon light emitting diodes (SPLEDs). These will exploit the unique properties of semiconductor nanostructures called self-assembled quantum rings, which we have recently used in novel VCSELs that operate at very low currents and at temperatures up to 110°C.