Gamma-ray lasers have been elusive because it’s hard to produce coherent gamma rays. Now, Luca Marmugi of University College London and colleagues have identified a gamma-ray lasing mechanism in a Bose–Einstein condensate (BEC) of 135Cs atoms in their isomeric state, 135mCs, that could be implemented with existing techniques. The mechanism is triggered by the spontaneous emission of one gamma photon, and relies on the transfer of the coherence of the BEC to the photon field. The 135mCs atoms can be made from proton-induced fission of actinides, followed by neutralisation, laser cooling and trapping. Standard techniques should allow trapping only of atoms in the desired state, so that a total population inversion is achieved.

Further reading

L Marmugi et al. 2018 Phys. Lett. B 777 281.