CAREER: Fundamental Discovery with Solid-State Spin Ensembles

This award is funded in part under the American Rescue Plan Act of 2021 (Public Law 117-2).

The nature of dark matter is one of the most fundamental open questions of modern science. As searches for the dark matter have advanced, axions - that arise naturally from model solutions of what is known as the strong-CP problem - and axion-like particles have emerged as particularly compelling candidates. The search for these particles opens an experimental window into physics at ultra-high energy scales, up to the Planck-scale, and discovery of axion-like dark matter would provide potential insight into the earliest evolutionary stages of the Universe. This CAREER award supports the development of a precision laboratory experimental platform based on solid-state electron and nuclear spin ensembles and magnetic sensing to advance the search for axions and axion-like particles with sensitivity in the nano-electronvolt to pico-electronvolt mass range. The award will develop an outreach program directed toward young students and the general public with a focus on developing non-standard problem-solving skills of complex real-world challenges. This program will partner with the Boston University GROW and MIT BLOSSOMS programs to develop novel online content with connections to the study of the cosmos and dark matter, and will focus on building connections with schools in the Boston-area with large populations of students.

This award leverages the established technical achievements of the Search for Halo Axions with Ferromagnetic Toroids (SHAFT) experimental platform. Specifically, the platform realizes a magnetic field sensitivity of 150 aT per square root(Hz) over a range of 10 kHz to 1 MHz, representing the most sensitive magnetic field measurement with a broadband magnetometer technology. Two primary measurements are planned as a part of the awarded activities. The first will operate the apparatus’ SQUID sensors within a dilution refrigerator at 0.1K temperature to improve the sensitivity to the electromagnetic coupling of axion-like dark matter to approximately 3e-12 GeV near 20 pico-electronvolt mass. This measurement would represent more than an order of magnitude improvement over current experimental sensitivities. The second complementary measurement will be made possible by integrating into the magnetic sensing apparatus solid crystals that host ensembles of nuclear spins, optimized for searches for time-varying nuclear electric dipole moments (EDMs) induced by the EDM interaction of axion-like dark matter. The search will involve high-resolution optical spectroscopy and measurements of the nuclear spin relaxation parameters, with the goal of achieving 20 percent nuclear spin polarization by direct optical pumping.

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.

Award Number: 2623365
Principal Investigator: Alexander Sushkov
Funds Obligated: $259,434
State: MD