Effect of relativistic motion on witnessing non-classicality of quantum   states
  We show that the operational definition of non-classicality of a quantum state depends on the motion of the observer. We use the relativistic Unruh-DeWitt detector model to witness nonclassicality of the probed field state. It turns out that the witness based on the properties of the P-representation of the quantum state depends on the trajectory of the detector. Inertial and noninertial motion of the device have qualitatively different impact on the performance of the witness. 
Agata Ch\k{e}ci\'nska, Krzysztof Lorek, Andrzej Dragan
quant-ph