Components for optical quantum information processing.


STM image of a GaSb quantum ringQuantum dots are nano-scale islands of one material embedded in a sea of another. They are described as artificial atoms as, in experiments, they share properties exhibited by those of simple atomic systems. This is somewhat amazing, as they are comprised of anywhere up to hundreds of thousands of atoms. Their scale, and the materials from which they are composed, allow them to be easily integrated into existing semiconductor devices. This has led many to predict a very exciting future for optoelectronics, with a new class of device that is able to exploit quantum mechanics at the level of individual quanta. The ability to process quantum information may play as important a role in our future lives as digital information does today, providing a resource with which to tackle efficiently some of the most complex problems currently considered. Quantum information technology is still in its infancy, and a lack of solid-state devices with which to create, store, process and measure quantum information acts as a bottleneck to its development. Research in the Young-Quantum group aims to investigate the potential of building these devices with quantum dot technology.

Quantum networkA wide variety of systems for representing quantum information have been researched and all have associated merits and flaws. The weaknesses inherent in one system can be side-stepped by combining it with another; quantum dots are interesting because they provide an interface between light and solid-state encoded information. Photons are excellent carriers of information due to the ease with which they can be encoded and the speed at which they travel, but they are difficult to store and process. Electrons interact with each other strongly and can be stored easily, but they are difficult to transfer over significant distances. The hybridisation of these two systems using quantum dots presents an ideal combination.