Tunneling of the 3rd Kind: A Test of the Effective Non-locality of   Quantum Field Theory
  Integrating out virtual quantum fluctuations in an originally local quantum field theory results in an effective theory which is non-local. In this Letter we argue that tunneling of the 3rd kind - where particles traverse a barrier by splitting into a pair of virtual particles which recombine only after a finite distance - provides a direct test of this non-locality. We sketch a quantum-optical setup to test this effect, and investigate observable effects in a simple toy model. 
Simon A. Gardiner, Holger Gies, Joerg Jaeckel, Chris J. Wallace
quant-ph hep-ph hep-th