Cavity-induced entanglement of trapped ions

The project unites two distinct areas of quantum information processing, single ions stored in radio-frequency traps, and single photons in optical fibres. In both fields, there have been spectacular advances recently. Strings of ions are presently the most successful implementation of quantum computing, with elementary quantum algorithms and quantum simulations realized. Photons are used to distribute entanglement over ever increasing distances. The principal challenge in the field is to enhance quantum processing power by scaling up current devices to larger quantum systems. We are pursuing the of the most promising strategies, distributed quantum computation, in which multiple small-scale ion processors are interlinked by exchanging photonic quantum bits via optical fibres. It requires an efficient quantum interface between ions and photons, mapping ionic to photonic quantum states and vice versa. To maximise fidelity and the success rate of the scheme, the interaction of ions and photons must take place in an optical cavity with high finesse, a technology in which the Ion Trap Cavity-QED and Molecular Physics group in Sussex has a leading role. The aim of this project is to investigate, optimise and evaluate schemes to generate entangled states between trapped ions and photons in different implementations such as polarisation, time bin or phase decoding. For this, cavity assisted Raman transitions will be employed to transfer the ion's state onto the photon in a deterministic way. The project is mainly experimental and will be conducted in the research labs in Sussex, the theoretical study of the schemes and possible developments of novel schemes will be pursued in collaboration with Peter Horak, University of Southampton.