There are many evidences in Quantum Mechanics about the existence of de Broglie waves: the two-slit experiment, self interference when a particle can follow two or more paths that converge, etc. There is not direct evidence of its existence because we use exclusively particle detectors. This paper presents a new evidence of the existence of de Broglie waves grounded in the action reaction principle. The action reaction principle is a fundamental ingredient of Physics: when two systems interact both change of state (i.e., they depart from the free, isolated evolution path in the phase space). A simple experiment using a Mach-Zehnder interferometer is analysed. A representation of the evolution in the phase space for different cases (isolated system and interaction with a detector) is shown. By applying the action reaction principle we show that some subsystem, different from the corpuscular photon, must follow one arm of the interferometer when we can infer that the photon follows the other arm. There cannot be interaction between the photodetector in one arm and the photon following the other arm. This new subsystem would be a distributed de Broglie wave.