A lower bound for the velocity of quantum communications in the preferred frame

An EPR experiment with polarized entangled photons is performed to test the Eberhard model. According to the Eberhard model, quantum correlations between space-like separated events are due to a superluminal communication signal propagating in a preferred frame. The coincidences between entangled photons passing through two polarizers aligned along a East-West axis are measured as a function of time during 21 sidereal days. No deviation from the predictions of the Quantum Theory is observed. Tacking into account for the experimental uncertainties, we infer that, if a preferred frame for superluminal signals exists which moves at velocity v→ with respect to the Earth, the modulus of the velocity of quantum communications in this frame has to be greater than vt≃0.6×104c for v<0.1c and for any arbitrary direction of v→.