Woodhouse College students, in collaboration with Orbyts Fellows Dr Markus Rademacher and Holly Owens from UCL Physics and Astronomy, conducted an investigation into the nature of dark matter by using a levitated optomechanical sensor. In this experiment, a silica sphere was trapped and levitated using highly focused laser beams.

The team's general idea was to identify the resonant frequency of the levitating particle, a crucial step since the highest detection sensitivity for any external force is found around this frequency. By analysing the particle's vibrations in three axes and converting this data into a mechanical spectrum, they were able to locate the resonant peaks. This allowed for the calculation of the noise floor and the minimum detectable dark matter coupling, demonstrating the sensor's sensitivity to a range of potential dark matter signals.

A significant outcome of this research is the development of a sensor with exquisite sensitivity to any signal that increases with mass, an important property for a dark matter detector. The experiment required no assumptions about dark matter beyond its gravitational coupling to other particles. The team successfully measured the resonant frequencies and the corresponding minimum dark matter signals that their sensor was most sensitive to, providing valuable constraints on potential dark matter models.

This research represents a step forward in our quest to understand the universe's elusive dark matter. By fine-tuning levitated sensors, we can begin to exclude largely unexplored regions of dark matter parameter space, steering the scientific community toward a correct model. Further work includes developing large arrays of these sensors, measuring directional information, and "cooling" the particle's motion to enhance sensitivity, all of which will help us continue to unravel this cosmic mystery!