Nonlinear Frequency Conversion of Photons for Quantum Networks

The development of technologies that exploit quantum physics to improve measurement, information processing, and communication is an area of rapid growth. Quantum devices such as memories and processors operate at different optical frequencies, typically outside the telecom range where losses in fibre are minimal. The goal of this studentship is to develop frequency-conversion techniques using nonlinear optics in optical fibre that will allow individual photons to be shifted between different wavelength bands. This will enable communication between the nodes of quantum devices operating at different optical frequencies; it will also allow low-loss, (and hence long-distance) exchange over fibre as well as photon conversion to frequencies where optimal detectors operate.

To be of value, use of quantum frequency translation must allow any small or large photon frequency shift within the visible and near infrared. The frequency conversion must also not alter properties of the photon other than its wavelength, including any entanglement with other systems. Furthermore, it should be highly efficient while not introducing additional 'noise' photons.

To meet the above requirements, frequency conversion of single photons will be investigated in photonic crystal fibre (PCF), optical fibres with a matrix of air holes running along their length, as well as subclasses of PCF such as bandgap fibre and hybrids thereof. In order to achieve this, new fibres will need to be designed and then fabricated in the university's state-of-the-art fibre fabrication facility. The project will involve theoretical and numerical analysis, fabrication, laboratory work using cutting-edge equipment, and participation in project meetings and reporting. Hence the full range of skills required for high-impact scientific research will be developed as well as communication and transferrable skills. There will be opportunities to present work at leading international conferences and to publish in high-quality peer-reviewed journals.

The project will be carried out in close collaboration with other members of the Networked Quantum Information Technologies hub being led by the University of Oxford, providing the opportunity to work on this individual experiment and simultaneously contribute to a larger joint research effort.