Rare earth ion waveguide architectures

Going beyond simple proof-of-principle demonstrations of quantum information devices will require building complex optical circuits that integrate many components, such as memories, sources, switches and detectors. Since rare earth crystals are a solid-state system, this can be achieved by migrating our quantum technologies from bulk crystals to a waveguide platform. The Laser Physics Centre has extensive photonic device fabrication facilities and, through this collaboration, we have developed a waveguide platform that offers great promise for constructing large, integrated rare earth quantum devices.

The challenge in fabricating rare earth waveguides is to preserve the exceptional coherence properties of the rare earths ions, which is what makes them so attractive for building quantum devices. Our approach was to use a passive planar waveguide. A high refractive index glass was deposited on a high quality bulk rare earth crystal. The optically active rare earth ions could then be addressed by the evanescent light field that extends into the crystal as light is guided in the glass. By monitoring the output of the waveguide, we were able to measure the coherence properties of the ions within 100 nm of the crystal surface, and confirm they matched the properties of the ions in the bulk crystal.

We now aim to make a multi-component device, where individual control of the components is achieved by applying voltages to electrodes on the chip to control how the rare earth ions interact with light. We are now adapting our current quantum information protocols to this new hardware system to demonstrate a large, integrate rare earth quantum processor.

Selected publications

Matthew Sellars

(02) 612 54571

Stephen Madden

(02) 612 58574