Causality, relativity and quantum correlation experiments with moving reference frames

Entanglement, one of the most important features of quantum mechanics, is a t the core of the famous Einstein-Bohr philosophical debate [1] and is the principal resource for quantum information processing [2]. We report on new experimental investigations of the properties of entangled photon pairs wi th emphasis on the tension between quantum mechanics and relativity [3,4]. Entangled photons are sent via an optical fiber network to two villages nea r Geneva, separated by more than 10 km where they are analyzed by interfero meters [5]. The photon pair source is set as precisely as possible in the c enter so that the two photons arrive at the detectors within a time interva l of less than 5 ps (corresponding to a path length difference of less than 1 mm). This sets a lower bound on the 'speed of quantum information' to 10 (7) times the speed of light. Next, one detector is set in motion [6] so th at both detectors, each in its own inertial reference frame, are first to d o the measurement! The data always reproduces the quantum correlations.