Scientists build quantum detector that measures microwave photons with 70% accuracy

Researchers at EPFL and partner universities built a detector that senses microwave photons using a double quantum dot coupled to a superconducting cavity.

The cavity absorbs microwaves in the 3–5.2 GHz band and transfers energy to the double quantum dot, producing a measurable current when photons are absorbed.

Measurements showed detection efficiencies between 55% and 67.7%, with a peak of 70%, and the device operates continuously and resets as electrons move.

The team published the results in Science Advances and says the semiconductor-based detector could aid spin-qubit quantum computing.