Applied Physics/Physics Colloquium: Savas Dimopoulos - "Superradiant Interactions of Cosmic Relics"

Abstract: Cosmic relics such as the cosmic neutrino background (CνB) are among the most compelling and elusive targets in fundamental physics. With conventional detectors, the interaction rate is so small that a 10-cm sphere of matter would see fewer than one event over the age of the universe. I will describe a framework in which this changes dramatically when macroscopic targets are prepared in simple quantum product states, as in NMR spin ensembles. In this regime, inelastic transitions of the target’s internal state can exhibit superradiant enhancements: the rate scales as N² with the number of constituents, boosting the CνB rate for a 10-cm sphere by ~20 orders of magnitude to ~1 Hz. I will present representative rates and discovery opportunities for relic neutrinos, axion and dark-photon dark matter, and local neutrino sources (reactor and solar), and explain why thermal-neutron scattering on NMR samples offers a natural first testbed for the needed quantum protocols. Finally, I will show how superradiant interactions appear as correlated noise on the target, motivating quantum observables beyond traditional energy-exchange measurements.

Savas Dimopoulos holds the Hamamoto Chair in the School of Humanities and Sciences at Stanford University. He is known for his novel proposals addressing the hierarchy problem, including Extended Technicolor, the Supersymmetric Standard Model, Large Extra Dimensions, and Split Supersymmetry. As a student, he was one of the early proponents of primordial baryogenesis. He later proposed a new class of gravitational wave detectors based on atom interferometry, now forming the basis of the MAGIS and AION projects in the US and UK. He also proposed searching for axions and other light bosons through black hole superradiance, an approach now pursued by LIGO/Virgo. More recently, he has proposed novel detectors based on special quantum configurations that can greatly enhance the detection prospects for dark matter, the primordial cosmic neutrino background, and nuclear reactor neutrinos.

He has received the Tomassoni Award and the Sakurai Prize of the APS “for his creative ideas on dynamical symmetry breaking, supersymmetry, and extra spatial dimensions, which have shaped theoretical research on TeV-scale physics, thereby inspiring a wide range of experiments.” He is a member of the U.S. National Academy of Sciences and the American Academy of Arts and Sciences, and was featured in the documentary Particle Fever.