The European Research Council (ERC) has bestowed a prestigious Synergy grant that will develop novel quantum sensors for experiments searching for dark matter. The DarkQuantum project, which is coordinated by the University of Zaragosa in Spain, has been funded with almost 13 million euros. The aim of which is the development of new quantum sensors and their application in experiments to search for axions, hypothetical particles that could make up dark matter. One of the experiments benefitting from this effort is the experiment BabyIAXO, a dark matter observatory under construction at DESY.

The ERC's “Synergy” projects aim to bring together the expertise of several principal investigators (between 2 and 4) to tackle very ambitious research, which could not be carried out individually. The researcher Igor García Irastorza, professor of physics at the University of Zaragoza and leader of the DESY-based International Axion Observatory (IAXO), will lead the DarkQuantum project. The project is based on the Irastorza’s extensive experience with this type of experiment, exploiting recent innovations in the field of quantum technologies. In addition to Irastorza, three other international experts in different aspects of quantum technologies are contributing, namely Takis Kontos of the École Normale Supérieure de Paris, Sorin Paraoanu of Aalto University in Finland, and Wolfgang Wernsdorfer of the Karlsruhe Institute of Technology.

DarkQuantum will develop new photon sensors based on recent advances, similar to those that now make it possible to build the quantum bits (or “qubits”) that make up the first quantum computers. Subsequently, these sensors will be installed in two experiments that will search for dark matter axions with a sensitivity never seen before. One of them is planned to be installed in the Canfranc Underground Laboratory, and will be the first experiment of its kind underground. The second will be installed inside the BabyIAXO magnet at DESY. BabyIAXO, a smaller preliminary version of the IAXO experiment, already received ERC funding in 2018.

Dark matter is a major component of the Universe, about five times more abundant than conventional matter, such as that comprising stars and planets. Its existence is known by the gravitational attraction it exerts on the surrounding visible matter, but its nature remains a mystery. One hypothesis is that dark matter is composed of particles that are neutral, very light, and that interact very weakly with ordinary matter, called axions. According to theory, axions could have been produced in large quantities after the Big Bang and behave exactly like the dark matter we observe. Proving the existence of axions is one of the most important challenges in particle physics today, and is also one of the goals of the DESY experiment ALPS-II, which is currently taking data.

The theory predicts that, if they exist, axions could be transformed into photons (and vice versa) within electromagnetic fields. This property is crucial for designing experiments that attempt to detect them. The axions of the dark matter halo in which our galaxy would be immersed would be transformed into potentially detectable photons inside resonant radiofrequency cavities, placed inside powerful magnets. This is the principle of “axion haloscopes” such as BabyIAXO and is one of the most promising avenues for attempting axion detection.

Unfortunately, the signals predicted by most theoretical models are too weak for current sensing technologies. However, quantum technologies allow the construction of systems that are ultra-sensitive to minute amounts of electromagnetic radiation, with much lower background noise than conventional technologies. DarkQuantum will apply this detection capability to the search for axions. If axions are indeed dark matter, DarkQuantum has a chance of making a major discovery with implications in particle physics, cosmology, and astrophysics.

“We are very happy being partner in this prestigious award,” says DESY scientist Axel Lindner, who leads the ALPS-II experiment and is involved with BabyIAXO. “It might provide a real game-changer in dark matter searches and in addition will help very much further enlarging quantum sensing expertise at DESY in general.”