Our research group focuses on developing novel solutions to the practical application of quantum information systems, by combining the growth of semiconductor nanostructures with nano-scale device processing, and novel optoelectronic control and measurement schemes.
The only commercial application of quantum information currently is quantum key distribution (QKD). QKD uses a negative rule imposed by quantum mechanics; that certain measurements can’t be made without disturbing the system being measured. If a communication channel is set up correctly, we can detect eavesdropping attempts using this simple principle of quantum physics, guaranteeing the security of the system. Technology based on this idea has matured, but it is currently limited to point-to-point links using bulky and expensive hardware. To make more versatile systems that are compatible with fibre-based internet architecture (pictured below) we are developing new elements for processing quantum information.
To date, international research has proposed numerous schemes and systems to achieve more complex quantum operations, such as memory and repetition. Elaborate arrangements utilising the excitation of atomic ensembles in macroscopic crystals have demonstrated quantum memory, but scaling potential is lacking. Quantum dots have received much attention for use in devices as they are highly scalable and can be integrated into semiconductor technology. Electron-nuclear interactions can induce dephasing that is too strong for memory applications, however, and cryogenic temperatures are typically required. In the group at Lancaster, we are pioneering a solution to the problem of dephasing, using the GaSb/GaAs material system. This system shows promise for achieving telecoms wavelength compatibility and room temperature operation.