Novel Cryogenic Methods for Fundamental Physics

The most fundamental description of physical reality – the so-called "standard model" – is a collection of fundamental particles, interactions, and symmetries knitted together by the mathematics of field theory. Laboratory tests of standard model (SM) so far agree with its predictions. This is a great mystery insofar as the SM is known to be wrong, or at least seriously incomplete because it cannot account for basic features of our universe. The SM predicts that essentially equal numbers of particles and antiparticles were created in the big bang, that would then collide and annihilate each other as the universe cooled, leaving no universe behind. The SM also can’t explain why the universe is made of matter rather than antimatter. Gravity does not fit well into the SM, and the SM has no explanation yet of either dark energy or dark matter – 95 percent of the energy and mass of the universe. This proposal is to explore and demonstrate 4 new ways to solve this mystery at a low temperature frontier. (1) To test the predicted quantum structure of the simplest atom with an unprecedented sensitivity, UV lasers will be developed to laser-cool hydrogen atoms in a beam for the first time. (2) To test the SM’s most precise prediction with a record precision, one-particle quantum systems will be probed for the first time with quantum-limited cryogenic detectors. (3) To search for and identify the mysterious dark matter, the first cryogenic cavity comparison apparatus will be designed, built and used for measurements. (4) To investigate quantum coherence of macroscopic objects and whether gravity can destroy such coherence, a novel cryogenic apparatus for such studies will be designed, built, and characterized. This is the first proposal to pool the unique experience of the 4 research groups in Northwestern's Center for Fundamental Physics (CFP), established to invent novel methods and "tabletop" apparatus that small teams can use to search for what is missing from the SM.