Physicists Propose a 'Neutrino Laser' Straight Out of Science Fiction

MIT physicists have proposed a way to make a super sci-fi-sounding device: a neutrino 'laser,' which could help us probe the mysteries of the Universe.

Neutrinos are the most abundant particles that have mass, but in a cruel irony, they're extremely elusive, earning them the term 'ghost particle'. Although there are trillions of them zipping through your body at any given moment, they interact with matter so rarely that they're almost impossible to study.

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So, physicists at MIT and the University of Texas at Arlington have outlined a concept for a neutrino laser that could help wrangle the wayward particles into a concentrated beam for easier analysis.

To make one, you'd theoretically need to cool a cloud of rubidium-83 atoms to a temperature colder than interstellar space to make them act like one quantum entity – a state of matter known as a Bose-Einstein Condensate (BEC).

Rubidium-83 is radioactive, producing neutrinos when the atoms decay. Normally, the atoms would decay somewhat randomly, spewing neutrinos in all directions at unpredictable times. If they're in a BEC state, however, their behavior should sync up, including their decay.

It bears at least a passing resemblance to a conventional laser, which produces and combs photons into a neat line. The end result should be a bright beam of neutrinos pointed in a single direction, within minutes of reaching the right temperature.

An artist's impression of rubidium-83 atoms (blue) decaying to produce neutrinos (orange), in a gaseous state (top) and a Bose-Einstein Condensate state (bottom). (APS/Alan Stonebraker)

Catching a neutrino in the act is a numbers game, and our current best experiments involve watching gigantic volumes of water or ice, in environments with little interference, and waiting for the rare instance when one smacks into a nucleus within sight. Knowing where neutrinos will be, within a much smaller volume, helps rig that game in our favor.

Being able to detect and study neutrinos more reliably could potentially help us solve some major mysteries of physics, including what dark matter is and why antimatter didn't wipe out the Universe as we know it.

Neutrinos' tendency to not interact with matter could also be put to good use for communications that can be beamed right through objects, even underground.

Of course, the first step would be to check if it's possible to actually build a neutrino laser.

"If it turns out that we can show it in the lab, then people can think about: Can we use this as a neutrino detector? Or a new form of communication?" says Joseph Formaggio, physicist at MIT. "That's when the fun really starts."

The research was published in the journal Physical Review Letters.