Publication

RF fields in the microwave and terahertz domain are ubiquitous for security and communications, however test equipment requires frequent recalibration and careful understanding of the perturbations caused by the antenna used for measurement. This project, a collaboration between researchers at the University of Strathclyde and Durham University, seeks to develop new all-optical field sensors operating in the microwave and terahertz domain using Rydberg atoms in a thermal vapour to act as microscopic antenna enabling metal-free probing, sub-wavelength imaging resolution and the ability to implement a traceable SI calibration offering superior sensitivity compared to existing technologies. Early results include a careful characterisation of linearity and optimal state choice for precision RF sensing using this approach.

As part of an EPSRC Quantum Technology Fellowship we developed a new experimental apparatus to perform two-qubit operations using individually trapped Cs atoms. Highlights from this work included first demonstrations of single atom imaging using an sCMOS camera, high-fidelity and long-coherence entanglement generation and the first native CNOT gate protocol based on electromagnetically induced transparency. This apparatus has now been rebuilt as part of the Quantum Error Correction using Cryogenic Dual-Species Arrays project which builds on these early milestones and will integrate the system into a 4 K cryostat.

Separately we investigated hybrid approaches to quantum networking by developing optimised NbN resonators at 15 GHz for coupling Rydberg states to superconducting microwave circuits in a 4 K environment in collaboration with the Quantum Devices group at Glasgow University lead by Martin Weides. We have shown theoretically that this system can be used for demonstrations of strong-coupling and active cooling providing Q factors of 10⁵ and above can be achieved.