Stimulated mutual annihilation: How to make a gamma-ray laser with positronium

Twenty years ago, Philip Platzman and Allen Mills, Jr. at Bell Laboratories proposed that a gamma-ray laser could be made from a Bose-Einstein condensate (BEC) of positronium, the simplest atom made of both matter and antimatter (1). That was a year before a BEC of any kind of atom was available in any laboratory. Today, BECs have been made of 13 different elements, four of which are available in laboratories of the Joint Quantum Institute (JQI), and JQI theorists have turned their attention to ...