"Charged" phonons in an external field: a QED analog with Bose-Einstein   condensates
  We propose a method for using ultracold atomic Bose-Einstein condensates, to form an analog model of a relativistic massive field that carries "charge" and interacts with an external nondynamical gauge field. Such a "scalar QED" analog model, may be useful for simulating various effects of QFT involving charged particles, such as the Schwinger pair-creation of charged phonons in a constant external field, and vacuum instability. 
Shay Leizerovitch and Benni Reznik
quant-ph cond-mat.quant-gas hep-th