Probing neutrino quantum decoherence at reactor experiments

We explore how well reactor antineutrino experiments can constrain or measure the loss of quantum coherence in neutrino oscillations. We assume that decoherence effects are encoded in the size of the neutrino wave-packet, $\sigma$. We find that the current experiments Daya Bay and the Reactor Experiment for Neutrino Oscillation (RENO) already constrain $\sigma>1.0\times 10^{-4}$ nm and estimate that future data from the Jiangmen Underground Neutrino Observatory (JUNO) would be sensitive to $\sigma<2.1\times 10^{-3}$ nm. If the effects of loss of coherence are within the sensitivity of JUNO, we expect $\sigma$ to be measured with good precision. The discovery of nontrivial decoherence effects in JUNO would indicate that our understanding of the coherence of neutrino sources is, at least, incomplete.