Time-ordering Dependence of Measurements in Teleportation
  We trace back the phenomenon of "delayed-choice entanglement swapping" as it was realized in a recent experiment to the commutativity of the projection operators that are involved in the corresponding measurement process. We also propose an experimental set-up which depends on the order of successive measurements corresponding to noncommutative projection operators. In this case entanglement swapping is used to teleport a quantum state from Alice to Bob, where Bob has now the possibility to examine the noncommutativity within the quantum history. 
Reinhold A. Bertlmann, Heide Narnhofer, and Walter Thirring
quant-ph math-ph math.MP