Superradiant Searches for Dark Photons in Two Stage Atomic Transitions

Abstract

We study a new mechanism to discover dark photon fields, by resonantly triggering two photon transitions in cold gas preparations. Using coherently prepared cold parahydrogen, coupling sensitivity for sub-meV mass dark photon fields can be advanced by orders of magnitude, with a modified light-shining-through-wall setup. We calculate the effect of a background dark photon field on the dipole moment and corresponding transition rate of cold parahydrogen pumped into its first vibrational excited state by counter-propagating laser beams. The nonlinear amplification of two photon emission triggered by dark photons in a cold parahydrogen sample is numerically simulated to obtain the expected dark photon coupling sensitivity.

43 pages, 11 figures. Added discussions on decoherence effects and the sensitivity corresponding to larger target number density. Matched published version