PM: Optomechanical Dark Matter Detectors

University Of Arizona, Tucson AZ

Investigators

Abstract

The origin of dark matter is one of the enduring scientific mysteries of our time. After four decades of searching, direct detection of a dark matter “particle” remains elusive, spurring calls for a comprehensive rethinking of the search space and detection strategy. Optomechanical sensors, which use light to probe minute deformations of solid-state objects, have emerged at the forefront, as they give access to a broad set of dark matter candidates which couple to the size or position of atoms. The aim of this project is to build a first generation optomechanical dark matter detector, drawing on techniques which have enabled optomechanical systems to operate at the quantum limit in recent years. Beyond fundamental physics, the project will address key challenges to the development of quantum sensors, such as scalability and decoherence mitigation. A broader goal is the education of a new generation of graduate students and postdocs with hybrid interests in particle and quantum physics, recognizing that the future quantum workforce will benefit from drawing upon a wide pool of scientific backgrounds. Specifically, the project will join experimentalists (the PI) and theory collaborators to explore detection of ultralight “dark photon” dark matter using an array of cryogenic optomechanical accelerometers. Each accelerometer is based on a frequency-tunable, ultra-high-Q silicon nitride membrane coupled to an optical cavity. Silicon nitride membranes are a well-established mechanical resonator technology and can have exceptionally low dissipation at millikelvin temperatures, giving access to pico-g acceleration sensitivities at acoustic frequencies. In this exploratory phase of the project, a prototype detector will be developed based on a single centimeter-scale membrane in a 4 K cryostat. The goal will be to eclipsing current constraints on dark photon dark matter in the 1.e-9 to 1.e-11 eV mass (1 kHz – 100 kHz Compton frequency) range set by the Eöt-Wash torsion balance experiments. Longer term efforts, involving an array of photonic crystal membranes probed at the standard quantum limit, will target order of magnitude improvement and give access to a variety of fundamental weak force tests. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.