tangle2  John Allison  May 2017

An example of the use of quantum entanglement of positron
annihilation photons

- A simple cube of water of side 4 m - see Tangle2DetectorContruction.cc.
- Positrons of zero energy are generated at the centre of the cube -
see gps.mac.
- G4EmLivermorePolarizedPhysics is selected - see tangle2,cc.

For a description of the implementation of entanglement see
G4VEntanglementClipBoard.hh.  It uses a C++ shared pointer to create
a "clip board" so that the two photons can communicate. What Geant4
decided to do to one influences what should happen to the other.
The specific clip board is G4eplusAnnihilationEntanglementClipBoard.hh.