Ketterle Team: "Neutrino Laser" Based on Quantum-Entangled Atomic Clouds Theoretically Infeasible

Nobel laureate Wolfgang Ketterle and his team have conducted a theoretical examination of a "neutrino laser" concept and concluded that the scheme is fundamentally difficult to realize. The research findings have been published in *Physical Review Letters*.

The concept was previously proposed by American physicists, with the core idea being the use of rubidium-87 atomic clouds or other unstable isotopes, placing them into specific quantum states to generate highly directional neutrino beams. According to the concept, if a neutrino source analogous to a laser could be constructed, it would help accelerate neutrino mass measurements and advance observational studies of the interconversion phenomena among different types of neutrinos.

The Ketterle team's key focus this time was whether a large number of atoms could cooperatively emit neutrinos and other fermions, similar to the synchronized release of photons in a conventional laser. The researchers established a simplified atomic cloud computational model, incorporating possible quantum interactions between atoms as well as the properties of neutrinos and other fermionic particles into the calculations.

The computational results show that the original "neutrino laser" concept did not fully account for the effects of collective excited states of fermions, and this collective behavior would hinder the formation of new neutrinos. In other words, even if radioactive atoms are placed in a quantum system resembling a Bose-Einstein condensate, they cannot produce synchronized amplified emission analogous to a photon laser.

The researchers point out that under such conditions, each decaying atom can only release a single neutrino, failing to trigger the envisioned "chain reaction," and thus cannot generate synchronized neutrino pulses from the atomic cloud. Based on this, the Ketterle team concludes that the scheme for constructing a neutrino laser based on quantum-entangled atomic clouds is not theoretically viable, which also casts doubt on the possibility of using such devices to study neutrino properties.