Physicists from the United States have theoretically demonstrated the fundamental feasibility of constructing a neutrino laser. The idea is based on the phenomenon of superradiance in a radioactive Bose-Einstein condensate. The scientists calculated that in a condensate of approximately one million rubidium-83 atoms, the half-life would be reduced from 86 days to two and a half minutes. The article was published in Physical Review Letters.
Neutrinos interact virtually never with matter, making them extremely difficult to study, despite playing an important role in both astrophysics (for example, in supernova dynamics) and fundamental particle physics. Currently, researchers have only learned to detect a few processes involving them, while parameters such as their precise masses or nature (Majorana or Dirac) remain unknown. Scientists are addressing the problem of rare events by building giant detectors containing tons of detecting material or by placing detectors near intense neutrino sources, such as a nuclear reactor. However, creating a compact, intense neutrino source remains a significant challenge.
Ben Jones (BJP Jones) of the University of Texas at Arlington and Joseph Formaggio (JA Formaggio) of the Massachusetts Institute of Technology have proposed a mechanism similar to Dicke superradiance, in which collective decay is accelerated by coherent quantum correlations in the medium. Normally, this amplifies photon emission, but in a Bose-Einstein condensate (BEC), all atoms share the same spatial wave function, and the proximity condition is automatically satisfied. As a result, each subsequent decay becomes indistinguishable in terms of which atom initiated it, and the amplitudes of such processes are additive. This leads to a collective acceleration of decay: the rate increases proportionally to the square of the number of particles in the BEC, and the resulting neutrino flux becomes coherent and amplified.
According to the authors' calculations, in a condensate of 106 rubidium-83 atoms, half the material will decay in just 148 seconds instead of tens of days. The scientists note that such a source can be considered analogous to a laser, but for neutrinos. They propose rubidium-83 as a viable candidate: it can be cooled by laser methods to form a condensate, it has suitable properties, and its decay products are easily detected using X-ray quanta. Furthermore, working with a mixture of stable rubidium-87 and radioactive rubidium-83 is possible, which should simplify the creation and containment of the condensate.
For now, the idea remains theoretical: it's not yet clear how exactly to cool the radioactive gas to condensate and how to manage the heating of the trap during decay. Nevertheless, the authors emphasize that they have demonstrated for the first time the possibility of coherent amplification of neutrino radiation, and this opens a fundamentally new path to creating neutrino sources.
Scientists continue to study neutrinos. Physicists recently determined the minimum size of their wave packet.
