We study topics in quantum optics and nonlinear optics using nanophotonic devices.  

Devices created and studied by our group members concentrate optical energy into nanoscale volume, enhancing nominally small effects such as the optical coupling of radiation pressure from single photons to the motion of mechanical nanoresonators. In the ultimate limit, even for a weak input consisting of only a single photon, these effects can significantly modify the linear response of a nanophotonic device, leading to fundamental studies and practical quantum technologies.

Diamond quantum optomechanics: building hybrid quantum systems

Diamond is host to impurities and defects that are one of the most promising qubits for quantum information processing. They have been used already in proof-of-principle quantum optics experiments, and if they can be incorporated into nanophotonic devices it is hoped that it will be possible to build practical quantum technologies, e.g. for quantum computing and networking.

We have developed a new and versatile approach for creating nanophotonic devices from diamond, and have shown that we can use these devices to couple light to nanomechanical oscillators as well as SiV and NV colour centres.

Using these and future devices, we are now working to create technologies aimed at quantum applications: quantum memories (based on both optomechanics and spin storage), efficient light-matter interfaces for quantum networking, quantum devices that harness phonons for controlling and coupling qubits, wavelength converters, and more.

Silicon photonic spin-optomechanical sensors

We have recently demontrated nanocavity optomechanical devices based on silicon photonics which can detect sources of torque with unprecedented sensitivity. These structures are currently being used to probe nanomagnetic phenomena and demomstrate magnetic field sensors with unique combination of spatial resolution, sensitivity and dynamic range.

Several projects are building on this success: creating sensors for detecting optical angular momentum (which is relevant to quantum and classical communication), performing multidimensional magnetometry, and going "beyond silicon" to improve device performance.

2D material based nanophotonics and optomechanics

2D materials, the most famous of which is graphene, are promising for sensing and quantum technology. Hexagonal boron nitride (hBN) is a layered 2D material that is exciting thanks to its ability to host quantum emitters / single photon sources. By combining hBN with silicon photonic devices, we recently demonstrated the very first cavity optomechanical system with this material, and are working to realize quantum technologies that utilize our ability to control photons and phonons within it.

Nonlinear optics

Thanks to its large electronic bandgap, GaP is one few semiconductors which is transparent at both visible and telecom wavelengths. This makes it a promising material for nonlinear and quantum optics applications involving frequency and photon pair conversion. These experiments are on-going, and have the potential to result in highly-efficient chip-based sources of quantum light. We recently demonstrated conversion of light from 1550nm to 775nm with record efficiency using these devices, and want to next use them to create entangled photon pairs for quantum communication.