Atomic defects in semiconductor crystals such as silicon carbide (SiC) are a well-established platform for quantum technologies due to their ability to absorb and emit single photons and to store quantum information within internal spin degrees of freedom. This internal spin state of the atomic defect (also known as a colour centre) affects its emission properties, and can therefore be optically measured. Colour centres in SiC can be used as quantum memories to store and retrieve information encoded on photons [1], or as quantum sensors through the interaction of the intrinsic spins with the environment [2]. 

A key challenge for colour centres is the variation in performance induced by strains in the local crystal lattice, which are extremely hard to eliminate in the material and are a bottleneck to scalability. While we are making progress in generating colour centres in deterministic locations [3], the capability to tune their optical properties in situ would allow a way to overcome the variation in local strain conditions. This would allow separate colour centres to be tuned to emit indistinguishable photons to use in quantum protocols such as entanglement-based communication schemes, for example.  

This project seeks to harness an optical cavity to control the colour centre emission through the Purcell effect, and then tune to this emission through use of a deformable mechanical element. Devices will be made in SiC, which is a mature industrial semiconductor compatible with complementary metal-oxide-semiconductor (CMOS) processing and hosts promising colour centres. The potential of developing optomechanical cavities in SiC has recently arisen with the development of SiC-on-insulator (SiCOI) [4], semiconductor substrates with thin-films of SiC over a material with lower refractive index, allowing light to be confined in the SiC layer. By defining and etching waveguide and resonator patterns in SiCOI, integrated photonic circuits can be developed to deliver light to/from the optomechanical cavity, and established processes exist at the UK National Ion Beam Centre in Surrey to create colour centres be single ion implantation. 

This project will involve the full device development lifecycle including simulation, design, microfabrication, characterisation and application of laboratory-based measurements to demonstrate optomechanical effects.