As cool as it would have been to wield lasers that produce a beam of neutrinos, recently two papers were published by MIT researchers that seem to dampen the likelihood of such lasers being at all possible. In a review paper by [Ana Maria Rey] et al. these two papers are investigated in more detail.

Although the concept behind a neutrino laser is rather simple, using the same superradiance effect involving a Bose-Einstein condensate (BEC) that allows for stimulation by photons to result in a synchronized direction of emitted photons, the idea of using a BEC of radioisotopes that naturally emit neutrinos in this fashion has now been effectively shot down.

The problem lies in taking the leap from photons with a BEC and applying this to a BEC of radioisotopes. Whereas photons are relatively low-energy at a mere 1 eV, a neutrino with 1+ MeV has a much greater kinetic effect on the particle that emitted it. Unlike a photon emitted by an atom, this leaves precious little time for the other particles in the BEC to be affected.

This first scenario is covered in the (paywalled) paper by [Yu-Kun Lu] et al. with their calculations showing that superradiance cannot occur with neutrinos in a BEC and thus a laser is impossible. In the (also paywalled) second paper by [Hanzhen Lin] et al. the question is asked whether the assumption that a BEC of a radioisotope will at all enhance radioactive decay, to which the answer is a curt ‘no’.

Although it’s impossible to prove a negative with the scientific method, these two studies have slammed close a couple of doors on the concept of a neutrino laser.