Can Bose-Einstein condensates enhance radioactive decay?
Hanzhen Lin, Yukun Lu, Wolfgang Ketterle
TL;DR
The paper analyzes proposals to use Bose-Einstein condensates to enhance radioactive decay, showing that single-body decay cannot be altered by many-body coherence and that collective enhancement requires maintaining coherence with decay products, which is not feasible for MeV-energy channels. It derives a general gain-threshold framework $G = N \Gamma \Omega$ with a multi-mode solid-angle factor $\Omega \approx (\lambda/d)^2$ and a coherence-time constraint $\tau_{\mathrm{coh}}$, predicting vanishing gains ($\sim 10^{-20}$) for gamma- and neutrino-emission scenarios. By examining specific gamma-ray, neutrino, and positronium-based proposals, the authors argue that incorrect assumptions about condensate 'memory' and an overestimated coherence time lead to misleading conclusions, and that practical amplification remains far from realizable. Overall, while the formalism clarifies when collective emission can occur in radioactive systems, BEC-based enhancement of decay at MeV energies remains orders of magnitude below viable gamma- or neutrino-laser operation.
Abstract
This paper lays out the principles of how Bose-Einstein condensates can modify radioactive decay. We highlight the challenges of many modes and short coherence times due to the $\approx$ MeV energies of the emitted radiation. Recent proposals for gamma ray and neutrino lasers claim that using a Bose-Einstein condensate as a source would solve these issues. We show that this is not the case, and the proposed experiments would have a gain of only $10^{-20}$ or smaller. We also analyze proposals for gamma ray lasers based on stimulated annihilation of positronium Bose-Einstein condensates.