About the project
Photonic quantum computers require the ability to temporarily store photons while measurements and feed-forward operations are performed. This project will develop integrated quantum buffers by combining rare-earth-ion-doped crystals with silicon nitride photonic circuits, replacing bulky optical-fibre delays with compact devices suitable for scalable photonic quantum processors.
Integrated photonics is a promising platform for large-scale quantum computing, enabling photon sources, optical circuits and detectors to be realised on a single chip. However, photons cannot simply be stopped while a quantum processor decides what to do next. Current systems route photons off-chip through hundreds of metres of optical fibre to provide the delays needed for measurement and feed-forward. As processors scale, these bulky fibre buffers present a major obstacle to fully integrated photonic quantum computers.
To overcome this challenge, this project will develop compact quantum buffers by integrating rare-earth-ion-doped crystals with silicon nitride (SiN) photonic circuits. You'll investigate thulium-doped yttrium aluminium garnet (TmYAG), using its exceptional optical coherence and controllable absorption to temporarily store GHz-bandwidth photons. The aim is to realise microsecond-scale delays within a millimetre-scale integrated device, replacing hundreds of metres of optical fibre.
You'll gain hands-on experience in cryogenic quantum optics, rare-earth-ion spectroscopy, integrated photonics and single-photon experiments. You'll develop atomic frequency comb quantum buffers, characterise their efficiency and coherence, and ultimately interface the devices with integrated single-photon sources. The project also provides opportunities to explore electrically controlled, on-demand photon retrieval.
You'll work within a multidisciplinary team spanning quantum memories and integrated photonics, with access to Southampton’s quantum optics laboratories and nanofabrication facilities. The project has strong links with the UK quantum industry, including ORCA Computing and Duality Quantum Photonics, providing opportunities to understand how these technologies could be translated into future photonic quantum processors.
