Researchers at Bristol University have developed a simple way to measure photons in quantum systems that can be easily extended to encryption and computing systems.

The technology devised by researchers from the Quantum Engineering Technology Lab uses a specially designed optical fibre that can generate single photons in an organised way, allowing them to measure one photon at a time using a simple measurement procedure based on an analogue of a coin flip.

The experiment simultaneously determined two complementary polarization properties of a single photon and achieved the best possible analysis of the photon pair. s.

“Until we managed it, it was not well known that such quantum-limited simultaneous measurements on a single photon qubit could be realised with a basic setup in such a simple way,” said Dr Adetunmise Dada, Senior Research Associate in Bristol’s Quantum Engineering Technology Labs.

“Our findings shed light on the limits of how much we can learn about different complementary properties of quantum systems by using practical measurement setups. It is also related to how well we can rely on the information security delivered by quantum protocols in real world implementations, since the same principles govern the limits on the information that is hackable by an eavesdropper in quantum key distribution.”

The researchers now plan to push the limits of quantum understanding even further, by testing whether their methodology could be applied to measuring multiple incompatible properties and in large-scale quantum states.

This would be built on a silicon integrated optics platform, which is a promising approach to creating multidimensional quantum states encoded in the path degree of freedom of single photons and an area that combines the regions world-leading skills in both quantum technologies and silicon chip design.

More details on the lab