Dark Matter
There is lots of evidence that the visible matter around us is only a small fraction of the matter in the universe. For example, we can observe the motion of galaxies inside galaxy clusters, and we can see that there has to be extra mass that is causing them to move differently than we would otherwise expect. So far, there have been no confirmed reports of the detection of a particle that could be this 'dark' matter. There are many theories as to what dark matter could be, and one of the most well-motivated ones is the axion.
Axions
The axion was proposed as part of the solution to another longstanding problem in physics, the strong CP problem. In its essence, this is the problem that two unrelated parts of physics cancel each other out to one part in 1010, which we call a fine-tuning problem. The existence of axions would solve this, and as a bonus they do a great job of explaining the many anomalies that point to dark matter. Axions are hard to detect because they interact extremely feebly with the visible matter that makes up our detectors.
Quantum Sensing
Because dark matter interacts so feebly, experiments that search for it must be equipped with sensors that are incredibly sensitive to small or rare signals and that contribute minimal noise. As detection technology has improved, it is increasingly necessary to use sensors with noise levels that are close to or even below the fundamental quantum limit from Heisenberg's uncertainty principle. We use and develop superconducting quantum sensors based on qubit and SQUID technology with applications to axion dark matter.