Haloscope

Dark Matter (DM) accounts for 85% of the mass of Universe and is key in explaining structure formation in the early Universe and why galaxies hold now together. Nonetheless, it has never been observed directly and it is only through its gravitational effects that we have inferred its presence. The discovery of the nature of DM is identified as one of the highest priorities in scientific roadmaps across the world, where positive detection would be heralded as one of the greatest scientific accomplishments of our time. While currently WIMPs (Weakly Interacting Massive Particles in the 1-1000 GeV mass range) are the most favoured candidate for dark matter is, a variety of other light dark matter candidates are equally plausible and gaining traction given the lack of results from underground experiments and the LHC in the hunt for dark matter. The Pauli exclusion principle dictates that below masses of about 100 eV, dark matter must be bosonic. Bosonic light dark matter with masses < 10 eV, such as axions and dark photons, have gained in popularity in the past two to three years and their detection has moved from a minor activity to a more competitive world-wide effort.

Recently, the Department of Energy in the US awarded USD 6.6 million to fund four projects aimed at studying dark matter particles of low mass. In September 2019, at NYUAD we embarked on a new project to hunt for dark photons in the 0.1-1 eV range using a multilayer dielectric optical haloscope. A stack made of dielectric bilayers (deposited by enhanced vapour chemical deposition on a quartz substrate) would allow dark matter particles to be converted into Standard Model photons. Such detectable photons would emerge perpendicular to the stack and then be focused on a light sensor by means of a lens. The work on the prototype has already begun with the stack being produced and analysis under a TEM and a first test at cryogenic temperature employing an APD foreseen for early 2021. The second stage of the experiment will employ a Transition Edge Sensor (TES), a superconducting single-photon sensor that works in a dilution refrigerator at the mK temperature. The synergy between high energy physics and quantum information science has been positively seen by the DoE in the US too, which has recently established—and awarded with USD 3.5 million—the Fermilab Quantum Institute with the aim of bridging quantum science and quantum technology and high energy physics.