Extracting Neutrinos from Atoms――A Novel Application of Coherence

Abstract

Radiative emission of neutrino pair (RENP) from a metastable excited state of an atom is supposed to be sensitive to neutrino properties such as absolute masses and Dirac-Majorana distinction. A rate enhancement mechanism using quantum coherence among atoms in a macroscopic target, macrocoherent amplification, is explained. The spectral rate of macrocoherently amplified RENP is theoretically evaluated in several setups. In addition, the results of experiments that exhibit the macrocoherent amplification in a two-photon QED process, paired superradiance (PSR), are also presented. We have observed an amplification of 10¹⁸ or larger in the PSR process of parahydrogen, which confirms the validity of the macrocoherent amplification.