Few-Photon Quantum Optics

EPSRC Alignment: Grow & Maintain areas - / Condensed matter: electronic structure , Light matter interaction and optical phenomena , Materials engineering - composites , Optical devices and subsystems , Photonic materials , Quantum devices components and systems , Quantum optics and information.

We will be studying the interactions, scattering and emission of quantum light within solid state devices. Photons are ideal carriers of quantum information, being fast, cheap and easy to encode with quantum-information carried in their polarisation, phase, time or path degrees of freedom. The challenge in developing useful applications of optical quantum technology is to demonstrate an advantage over classical systems when sources and detectors are not perfect. Applications in low light level imaging, secure communications and quantum computing are likely for devices to be developed. Amongst solid state quantum emitters, Indium-Gallium-Arsenide quantum dots offer the highest efficiency and purity but only at cryogenic temperatures. However, emitters in wide-bandgap materials, such as diamond and boron-nitride offer the unique capability to emit quantum light at room temperature.

The focus of the project will be on increasing the efficiency, purity and repetition rate of single photon sources using novel designs of microcavity to alter the emission characteristics of the device. In year 1 of this project the student will design microcavities using a commercial photonics software package and create structures in the Institute for Compound Semiconductors cleanroom at Cardiff University. In Year 2 the student will optimise the photon collection apparatus to be portable, stable and efficient. The student will use the University's new superconducting single photon detectors, which have detection efficiency over 85% to single photons, to characterise their devices. In year 3 the student will define and develop prototype systems to demonstrate a quantum advantage over equivalent classical devices.