Interference between the atmospheric and solar oscillation amplitudes

We propose to detect the interference effect between the atmospheric-scale and solar-scale waves of neutrino oscillation, one of the key consequences of the three-generation structure of leptons. In vacuum, we show that there is a natural and general way of decomposing the oscillation amplitude into these two oscillation modes. The nature of the interference is cleanest in the (nu) over bar (e) disappearance channel, since it is free from the CP phase delta. We find that the upcoming JUNO experiment offers an ideal setting to observe this interference with more than 4 sigma significance, even under conservative assumptions about the systematic uncertainties. Finally, we discuss the relationship between the mass-ordering resolution and the interference effect.