Hybrid cavity QED with Rydberg ions and superconducting circuits

Hybrid approaches to quantum computing combine the attractive characteristics of multiple physical systems. In this project the aim is to couple ions in circular Rydberg states to a superconducting resonator. Circular Rydberg states have long lifetimes which makes them suitable for use as a quantum memory, whereas superconducting qubits have fast gate times but short coherence times.

At UCL we are in a world leading position, as the experimental apparatus for coupling a beam of neutral Rydberg atoms to a superconducting resonator has already been realised. Coupling Rydberg ions will be the next iteration to an already best in class result.

The research will begin by devising a scheme to pre- pare a beam of Barium ions in circular Rydberg states and performing microwave spectroscopy, which offers the ability to measure the states with unprecedented precision. In phase two of the project the Rydberg ion beam will be incorporated into the Rydberg atom - resonator coupling experiment. The ultimate aim will be to trap a single Rydberg ion close to the resonator and achieve strong coupling. This result could open up avenues such as coupling Rydberg ions via superconducting circuitry, and microwave to optical photon conversion which is a requirement for quantum networks.

The first and most important impact of our Centre will be through the cross-disciplinary technical training it provides for its students. Through this training, they will have not only skills to control and exploit quantum physics in new ways, but also the background in device engineering and information science to bring these ideas to implementation and to seek out new applications. Our commercial and governmental partners tell us how important these skills are in the growing number of people they are hiring in the field of quantum technologies. In the longer term we expect our graduates to be prominent in the development of new technologies and their application to communication, information processing, and measurement science in leading university and government laboratories as well as in commercial research and development. In the shorter term we expect them to be carrying out doctoral research of the highest international quality.

Second, impact will also flow from the students' approach to enterprise and technology transfer. From the outset they will be encouraged to think about the value of intellectual property, the opportunity it provides, and the fundraising needed to support research and development. As students with this mindset come to play a prominent part in university and commercial laboratories, their common background will help to break down the traditional barriers between these sectors and deliver the promise of quantum technologies for the benefit of the UK and world economies. Concrete actions to accelerate this impact will include entrepreneurship training and an annual CDT industry day.

Third, through the participation it nucleates in the training programme and in students' research, the Centre will bring together a community of partners from industry and government laboratories. In the short term this will facilitate new collaborations and networks involving the partners and the students; in the long term it will help to ensure that the supply of highly skilled people from the CDT reaches the parts of industry that need them most.

Finally, the CDT will have a strong impact on the quantum technologies training landscape in the UK. The Centre will organise training events and workshops open to all doctoral researchers to attend. We will also collaborate with CDTs in the quantum technologies and related research areas to coordinate our efforts and maximise our joint impact. Working in consort, these CDTs will form a vibrant national training network benefitting the entire UK doctoral research community.