# Is it possible to transform energy stored in anti-matter into coherent radiation?

In Travellers, a sci-fi show on netflix, they have 10g of some form of anti-matter floating around. A quick $$mc^2$$ calculation gives a quantity of $$E = 10^{15} J$$. For reference, Little Boy released $$63 \times 10^{12} J$$. That's a massive amount of energy, I thought that they wanted a way to defuse'' this anti-matter bomb safely, so when they mention in passing that an X-ray laser could remove energy from anti-matter into a coherent beam of X-rays, I was intrigued by this from an atomic physics perspective (and also wrong about what they wanted to do with it. This quote is somewhere past 24 minutes in in Season 1, Episode 6).

The exact quote is

An X-ray laser works by translating a very specific amount of energy from an anti-matter or nuclear explosion into a coherent beam of X-rays. Too much, and you overload the laser. Too little and it won't deflect the target.

I don't understand what the second parts meant. But in bold, it highlights the process. I was curious how much of this physics was actually possible. As far as I can tell they want to coherently drive, something akin to positronium, but possibly made out of protons, into the ground state while utilizing that energy in the form of electromagnetic radiation. How could someone do this in principle?

To me, this seemed entirely within the realm of possibility, as we already know that it is possible to take an excited state of an atom, drive it coherently, via a $$\pi$$-pulse, and end up with something in the ground state and the energy emitted into light. I'm not sure of the exact details of how one would convert anti-matter into coherent radiation, and if it's possible to get out that energy in something other than it's characteristic frequency $$\omega = E/\hbar$$. Could one power a visible light laser for example via some highly non-resonant process?

It's such a fascinating question, it makes me wonder if it were possible, then we could probably have incredibly dense energy storage that would be able to power anything of interest far past our lifetimes. I'm mostly asking to share the question with you all because I think it's so interesting!

For concreteness, we can assume that the anti-matter is anti-hydrogen and we're free to dissociate it into it's parts for energy extraction via interaction with normal matter. Use whatever laser traps, magnetic traps you want.

• For what it's worth, you'd never use the term 'x-ray' for radiation which couples to matter-antimatter creation or annihilation processes. The lowest energy for such radiation is past the 1 MeV threshold, and that's well into the gamma-ray regime; there's a gray area where both x-ray and gamma ray are acceptable but that stops well short of what you want. – Emilio Pisanty Jan 1 at 2:52

The other idea was a theoretical concept published by Soviet scientist L A Rivlan. In this concept a laser irradiates a source of free electrons and positrons (or positronium) and stimulates the annihilation process. In order to accomplish this the laser energy would have to equal or exceed $$2mc^2$$ in the center of mass frame of the matter/antimatter pair. One version of this concept involved irradiating a velocity matched beam of electrons and positrons head-on (ie the laser radiation propagates in the direction opposite to the direction of the particle beam). As the energy of the particle beam increases the matching laser energy decreases. The stimulated emission would yield a $$\gamma-ray$$ laser pulse carrying the full energy of the electron\positron pair (both rest energy and kinetic energy) in the same direction as the particle beam.