A team of MIT physicists has concluded that a proposed neutrino laser cannot be built, even with technology far more advanced than what is currently available. Their findings, published in two papers in Physical Review Letters, show that fundamental laws of physics prevent the concept from working.
A proposed neutrino laser would produce a focused, laser-like beam of neutrinos.
The concept of a neutrino laser was proposed by Professor Joe Formaggio of MIT and Dr. Ben Jones of the University of Texas at Arlington. The ambitious idea was inspired by the way ordinary lasers generate coherent beams of light.
The researchers suggested cooling a cloud of radioactive atoms to nanokelvin temperatures—just billionths of a degree above absolute zero. Under these conditions, the atoms could form a Bose-Einstein condensate, an unusual quantum state in which many atoms behave as a single, synchronized system.
In theory, radioactive decay inside the condensate could become dramatically enhanced. The resulting neutrinos might then be emitted in a narrow, laser-like beam, potentially shortening the radioactive half-life of the atoms.
However, MIT Professor Wolfgang Ketterle, a Nobel Prize winner who helped discover Bose-Einstein condensates in 1995, and MIT physicists Hanzhen Lin and Yu-Kun Lu have shown that the proposal is fundamentally impossible.
In a two-part analysis, the researchers examined whether a neutrino laser could produce the necessary quantum amplification. They also investigated a related proposal for coherent gamma-ray emission.
Neutrinos produced through radioactive decay carry roughly one million times more energy than the visible photons used in conventional lasers. As a result, the atoms emitting the neutrinos would experience an enormous recoil, moving at speeds comparable to Mach 10.
This recoil would rapidly eject the atoms from the Bose-Einstein condensate, leaving insufficient time for the quantum interactions required to amplify the emission and produce a coherent neutrino beam.
“As long as the recoil atoms remain within the condensate, we can make the condensate superradiant,” Ketterle said.
“But when a neutrino is emitted at a million electron volts, the atom recoils at a speed equivalent to Mach 10, faster than a fighter jet. This is so fast that the atom leaves the condensate almost instantly.”
Even if the necessary quantum correlations could somehow form, the second study found that they would work against the proposed neutrino laser mechanism. Instead of encouraging the condensate to emit the next neutrino in the same direction, the correlations would favor the opposite direction and prevent the beam from growing.
The researchers attribute this inverse correlation to the fact that neutrinos are fermions. These particles obey different quantum-statistical rules from photons, the bosons that enable superradiance and conventional laser emission.
“These two papers are like punch one and punch two,” Ketterle said. “The papers would have rejected the proposal.”
Formaggio welcomed the analysis as an example of the scientific process.
“When new ideas like the one we proposed are shared, it is the community’s duty to vet them,” Formaggio said.
“This is the scientific process, and it was great to see that our paper actually generated a lot of thinking beyond our initial concepts. We think that is going to continue.”
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Lu Yukun et al. 2026. A superradiant neutrino laser is fundamentally impossible. Physical Review Letters 137, 101804; doi: 10.1103/8x7k-rwx2
Lin Hanzhen et al. 2026. Can Bose-Einstein condensates promote radioactive decay? Physical Review Letters 137, 101805; doi: 10.1103/rnx6-wqpf
Source: www.sci.news