The goal of this research line is to create quantum opto-electronic devices that operate as quantum repeater nodes in a secure quantum network. Our material of choice is silicon carbide, a semiconductor of wide industrial use with a unique combination of excellent properties.
By using silicon carbide, our quantum devices can integrate all functionalities required to operate as quantum nodes in a secure quantum network:
- spintronic functionalities. We implement the quantum bits in the network node with individual electronic and nuclear spins associated to optically-active point defects in silicon carbide. Being insensitive to electric noise, spins can preserve fragile quantum states over long time.
- photonic functionalities. The electronic spin in the node is interfaced to optical photons, used as long-distance carrier of quantum states in the network. This is achieved by exploiting atomic-like spin-selective optical transitions associated to the point defects we use. To achieve high-quality interfacing, photons need to be collected very efficiently through ad-hoc photonic structures, such as waveguides, microcavities or solid immersion lenses. While photonics in SiC is less developed than in other platforms such as silicon or silicon nitride, it is a very promising material due its wide transparency range and strong nonlinear coefficients.
- electronic functionalities. By integrating the single spin in micro-electronic device, such as p-i-n diodes, we can locally control the electric environment, enabling tuning of the number of trapped electrons and minimising unwanted electrical noise detrimental for spin-photon interfacing.
Our SiC work benefits from collaborations with European partners, for example through the QuantTELCO FET open collaboration. We partner with leading UK experts on SiC power devices (e.g. Dr Vishal Shah in Warwick, Dr Alton Horsfall in Durham) and SiC photonics (Dr Alberto Politi in Southampton).