If we can both generate and detect neutrinos, we have the basis for a communication device that can operate on a point-to-point basis between any two locations. If Europe wants to send a secret message to Australia, it can point its transmitter towards the ground, and fire the beam through the interior of the Earth. It is very unlikely that there will be anybody in between to intercept the signal. There may be more p…
AIUI, you’ll need a much bigger detector farther from the beam location, and the bandwidth is going to suck at any range, but, sure, the odds that someone sticks a neutrino detector in the path is pretty low.