Single Photon Quantum Logic

This project involves the fabrication, testing, and measurement of optical semiconductor devices containing quantum dots. These devices will be developed for single photon quantum logic applications.
The project will begin by investigating quantum dots which are embedded in GaAs micropillar cavity structures and emit photons at 900nm. Resonant excitation will be used to produce single photons. The non-linear interaction between the photons and the spin in the quantum dot will be used to rotate the polarisation of single photons. This will form a kind of switching mechanism that could be used for quantum logic applications.
The project will then move on to investigate a range of quantum dot semiconductor structures which can be resonantly excited in order to emit photons in the telecom C-band. Micropillars will be investigated, as well as alternatives such as solid immersion lenses. Since these types of structures have not previously been made using 1550nm InP emitters, they will have to be designed and simulated using Comsol before fabrication can begin. Based on the simulation results, novel fabrication techniques may need to be developed in order to overcome any limitations due to using GaAs fabrication methods on InP. The intensity enhancement and coherence times of the structures will be measured and fabrication iterations done to improve these figures of merit. Rabi oscillations will be measured, and resonant excitation will be used to create experiments which could be developed for use in quantum logic. It is likely that applications of quantum logic like quantum computing will be part of a larger, long-distance network. It is therefore useful to develop structures which emit in the telecom C-band and can be integrated into existing fibre networks.